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Sample records for mlh3 missense mutations

  1. Localization of MLH3 at the Centrosomes

    PubMed Central

    Roesner, Lennart M.; Mielke, Christian; Faehnrich, Silke; Merkhoffer, Yvonne; Dittmar, Kurt E. J.; Drexler, Hans G.; Dirks, Wilhelm G.

    2014-01-01

    Mutations in human DNA mismatch repair (MMR) genes are commonly associated with hereditary nonpolyposis colorectal cancer (HNPCC). MLH1 protein heterodimerizes with PMS2, PMS1, and MLH3 to form MutLα, MutLβ, and MutLγ, respectively. We reported recently stable expression of GFP-linked MLH3 in human cell lines. Monitoring these cell lines during the cell cycle using live cell imaging combined with confocal microscopy, we detected accumulation of MLH3 at the centrosomes. Fluorescence recovery after photobleaching (FRAP) revealed high mobility and fast exchange rates at the centrosomes as it has been reported for other DNA repair proteins. MLH3 may have a role in combination with other repair proteins in the control of centrosome numbers. PMID:25116689

  2. Analyzing effects of naturally occurring missense mutations.

    PubMed

    Zhang, Zhe; Miteva, Maria A; Wang, Lin; Alexov, Emil

    2012-01-01

    Single-point mutation in genome, for example, single-nucleotide polymorphism (SNP) or rare genetic mutation, is the change of a single nucleotide for another in the genome sequence. Some of them will produce an amino acid substitution in the corresponding protein sequence (missense mutations); others will not. This paper focuses on genetic mutations resulting in a change in the amino acid sequence of the corresponding protein and how to assess their effects on protein wild-type characteristics. The existing methods and approaches for predicting the effects of mutation on protein stability, structure, and dynamics are outlined and discussed with respect to their underlying principles. Available resources, either as stand-alone applications or webservers, are pointed out as well. It is emphasized that understanding the molecular mechanisms behind these effects due to these missense mutations is of critical importance for detecting disease-causing mutations. The paper provides several examples of the application of 3D structure-based methods to model the effects of protein stability and protein-protein interactions caused by missense mutations as well. PMID:22577471

  3. Two novel missense mutations in nonketotic hyperglycinemia.

    PubMed

    Yilmaz, Berna Seker; Kor, Deniz; Ceylaner, Serdar; Mert, Gulen Gul; Incecik, Faruk; Kartal, Erkan; Mungan, Neslihan Onenli

    2015-05-01

    Nonketotic hyperglycinemia (OMIM no. 605899) is an autosomal recessively inherited glycine encephalopathy, caused by a deficiency in the mitochondrial glycine cleavage system. Here we report 2 neonates who were admitted to the hospital with complaints of respiratory failure and myoclonic seizures with an elevated cerebrospinal fluid/plasma glycine ratio and diagnosed as nonketotic hyperglycinemia. We report these cases as 2 novel homozygous mutations; a missense mutation c.593A>T (p.D198 V) in the glycine decarboxylase gene and a splicing mutation c.339G>A (Q113Q) in the aminomethyltransferase gene were detected. We would like to emphasize the genetic difference of our region in inherited metabolic diseases once again. PMID:24838951

  4. Molecular mechanisms of disease-causing missense mutations

    PubMed Central

    Stefl, Shannon; Nishi, Hafumi; Petukh, Marharyta; Panchenko, Anna R.; Alexov, Emil

    2013-01-01

    Genetic variations resulting in a change of amino acid sequence can have a dramatic effect on stability, hydrogen bond network, conformational dynamics, activity and many other physiologically important properties of proteins. The substitutions of only one residue in a protein sequence, so-called missense mutations, can be related to many pathological conditions, and may influence susceptibility to disease and drug treatment. The plausible effects of missense mutations range from affecting the macromolecular stability to perturbing macromolecular interactions and cellular localization. Here we review the individual cases and genome-wide studies which illustrate the association between missense mutations and diseases. In addition we emphasize that the molecular mechanisms of effects of mutations should be revealed in order to understand the disease origin. Finally we report the current state-of-the-art methodologies which predict the effects of mutations on protein stability, the hydrogen bond network, pH-dependence, conformational dynamics and protein function. PMID:23871686

  5. Comparison of predicted and actual consequences of missense mutations.

    PubMed

    Miosge, Lisa A; Field, Matthew A; Sontani, Yovina; Cho, Vicky; Johnson, Simon; Palkova, Anna; Balakishnan, Bhavani; Liang, Rong; Zhang, Yafei; Lyon, Stephen; Beutler, Bruce; Whittle, Belinda; Bertram, Edward M; Enders, Anselm; Goodnow, Christopher C; Andrews, T Daniel

    2015-09-15

    Each person's genome sequence has thousands of missense variants. Practical interpretation of their functional significance must rely on computational inferences in the absence of exhaustive experimental measurements. Here we analyzed the efficacy of these inferences in 33 de novo missense mutations revealed by sequencing in first-generation progeny of N-ethyl-N-nitrosourea-treated mice, involving 23 essential immune system genes. PolyPhen2, SIFT, MutationAssessor, Panther, CADD, and Condel were used to predict each mutation's functional importance, whereas the actual effect was measured by breeding and testing homozygotes for the expected in vivo loss-of-function phenotype. Only 20% of mutations predicted to be deleterious by PolyPhen2 (and 15% by CADD) showed a discernible phenotype in individual homozygotes. Half of all possible missense mutations in the same 23 immune genes were predicted to be deleterious, and most of these appear to become subject to purifying selection because few persist between separate mouse substrains, rodents, or primates. Because defects in immune genes could be phenotypically masked in vivo by compensation and environment, we compared inferences by the same tools with the in vitro phenotype of all 2,314 possible missense variants in TP53; 42% of mutations predicted by PolyPhen2 to be deleterious (and 45% by CADD) had little measurable consequence for TP53-promoted transcription. We conclude that for de novo or low-frequency missense mutations found by genome sequencing, half those inferred as deleterious correspond to nearly neutral mutations that have little impact on the clinical phenotype of individual cases but will nevertheless become subject to purifying selection. PMID:26269570

  6. Comparison of predicted and actual consequences of missense mutations

    PubMed Central

    Miosge, Lisa A.; Field, Matthew A.; Sontani, Yovina; Cho, Vicky; Johnson, Simon; Palkova, Anna; Balakishnan, Bhavani; Liang, Rong; Zhang, Yafei; Lyon, Stephen; Beutler, Bruce; Whittle, Belinda; Bertram, Edward M.; Enders, Anselm; Goodnow, Christopher C.; Andrews, T. Daniel

    2015-01-01

    Each person’s genome sequence has thousands of missense variants. Practical interpretation of their functional significance must rely on computational inferences in the absence of exhaustive experimental measurements. Here we analyzed the efficacy of these inferences in 33 de novo missense mutations revealed by sequencing in first-generation progeny of N-ethyl-N-nitrosourea–treated mice, involving 23 essential immune system genes. PolyPhen2, SIFT, MutationAssessor, Panther, CADD, and Condel were used to predict each mutation’s functional importance, whereas the actual effect was measured by breeding and testing homozygotes for the expected in vivo loss-of-function phenotype. Only 20% of mutations predicted to be deleterious by PolyPhen2 (and 15% by CADD) showed a discernible phenotype in individual homozygotes. Half of all possible missense mutations in the same 23 immune genes were predicted to be deleterious, and most of these appear to become subject to purifying selection because few persist between separate mouse substrains, rodents, or primates. Because defects in immune genes could be phenotypically masked in vivo by compensation and environment, we compared inferences by the same tools with the in vitro phenotype of all 2,314 possible missense variants in TP53; 42% of mutations predicted by PolyPhen2 to be deleterious (and 45% by CADD) had little measurable consequence for TP53-promoted transcription. We conclude that for de novo or low-frequency missense mutations found by genome sequencing, half those inferred as deleterious correspond to nearly neutral mutations that have little impact on the clinical phenotype of individual cases but will nevertheless become subject to purifying selection. PMID:26269570

  7. Variable phenotypes are associated with PMP22 missense mutations.

    PubMed

    Russo, M; Laurá, M; Polke, J M; Davis, M B; Blake, J; Brandner, S; Hughes, R A C; Houlden, H; Bennett, D L H; Lunn, M P T; Reilly, M M

    2011-02-01

    Charcot-Marie-Tooth disease (CMT) is the commonest hereditary neuropathy encompassing a large group of clinically and genetically heterogeneous disorders. The commonest form of CMT, CMT1A, is usually caused by a 1.4 megabase duplication of chromosome 17 containing the PMP22 gene. Mutations of PMP22 are a less common cause of CMT. We describe clinical, electrophysiological and molecular findings of 10 patients carrying PMP22 missense mutations. The phenotype varied from mild hereditary neuropathy with liability to pressure palsies (HNPP) to severe CMT1. We identified six different point mutations, including two novel mutations. Three families were also found to harbour a Thr118Met mutation. Although PMP22 point mutations are not common, our findings highlight the importance of sequencing the PMP22 gene in patients with variable CMT phenotypes and also confirm that the PMP22 Thr118Met mutation is associated with a neuropathy albeit with reduced penetrance. PMID:21194947

  8. Comprehensive assessment of cancer missense mutation clustering in protein structures.

    PubMed

    Kamburov, Atanas; Lawrence, Michael S; Polak, Paz; Leshchiner, Ignaty; Lage, Kasper; Golub, Todd R; Lander, Eric S; Getz, Gad

    2015-10-01

    Large-scale tumor sequencing projects enabled the identification of many new cancer gene candidates through computational approaches. Here, we describe a general method to detect cancer genes based on significant 3D clustering of mutations relative to the structure of the encoded protein products. The approach can also be used to search for proteins with an enrichment of mutations at binding interfaces with a protein, nucleic acid, or small molecule partner. We applied this approach to systematically analyze the PanCancer compendium of somatic mutations from 4,742 tumors relative to all known 3D structures of human proteins in the Protein Data Bank. We detected significant 3D clustering of missense mutations in several previously known oncoproteins including HRAS, EGFR, and PIK3CA. Although clustering of missense mutations is often regarded as a hallmark of oncoproteins, we observed that a number of tumor suppressors, including FBXW7, VHL, and STK11, also showed such clustering. Beside these known cases, we also identified significant 3D clustering of missense mutations in NUF2, which encodes a component of the kinetochore, that could affect chromosome segregation and lead to aneuploidy. Analysis of interaction interfaces revealed enrichment of mutations in the interfaces between FBXW7-CCNE1, HRAS-RASA1, CUL4B-CAND1, OGT-HCFC1, PPP2R1A-PPP2R5C/PPP2R2A, DICER1-Mg2+, MAX-DNA, SRSF2-RNA, and others. Together, our results indicate that systematic consideration of 3D structure can assist in the identification of cancer genes and in the understanding of the functional role of their mutations. PMID:26392535

  9. Comprehensive assessment of cancer missense mutation clustering in protein structures

    PubMed Central

    Kamburov, Atanas; Lawrence, Michael S.; Polak, Paz; Leshchiner, Ignaty; Lage, Kasper; Golub, Todd R.; Lander, Eric S.; Getz, Gad

    2015-01-01

    Large-scale tumor sequencing projects enabled the identification of many new cancer gene candidates through computational approaches. Here, we describe a general method to detect cancer genes based on significant 3D clustering of mutations relative to the structure of the encoded protein products. The approach can also be used to search for proteins with an enrichment of mutations at binding interfaces with a protein, nucleic acid, or small molecule partner. We applied this approach to systematically analyze the PanCancer compendium of somatic mutations from 4,742 tumors relative to all known 3D structures of human proteins in the Protein Data Bank. We detected significant 3D clustering of missense mutations in several previously known oncoproteins including HRAS, EGFR, and PIK3CA. Although clustering of missense mutations is often regarded as a hallmark of oncoproteins, we observed that a number of tumor suppressors, including FBXW7, VHL, and STK11, also showed such clustering. Beside these known cases, we also identified significant 3D clustering of missense mutations in NUF2, which encodes a component of the kinetochore, that could affect chromosome segregation and lead to aneuploidy. Analysis of interaction interfaces revealed enrichment of mutations in the interfaces between FBXW7-CCNE1, HRAS-RASA1, CUL4B-CAND1, OGT-HCFC1, PPP2R1A-PPP2R5C/PPP2R2A, DICER1-Mg2+, MAX-DNA, SRSF2-RNA, and others. Together, our results indicate that systematic consideration of 3D structure can assist in the identification of cancer genes and in the understanding of the functional role of their mutations. PMID:26392535

  10. Missense dopamine transporter mutations associate with adult parkinsonism and ADHD

    PubMed Central

    Hansen, Freja H.; Skjørringe, Tina; Yasmeen, Saiqa; Arends, Natascha V.; Sahai, Michelle A.; Erreger, Kevin; Andreassen, Thorvald F.; Holy, Marion; Hamilton, Peter J.; Neergheen, Viruna; Karlsborg, Merete; Newman, Amy H.; Pope, Simon; Heales, Simon J.R.; Friberg, Lars; Law, Ian; Pinborg, Lars H.; Sitte, Harald H.; Loland, Claus; Shi, Lei; Weinstein, Harel; Galli, Aurelio; Hjermind, Lena E.; Møller, Lisbeth B.; Gether, Ulrik

    2014-01-01

    Parkinsonism and attention deficit hyperactivity disorder (ADHD) are widespread brain disorders that involve disturbances of dopaminergic signaling. The sodium-coupled dopamine transporter (DAT) controls dopamine homeostasis, but its contribution to disease remains poorly understood. Here, we analyzed a cohort of patients with atypical movement disorder and identified 2 DAT coding variants, DAT-Ile312Phe and a presumed de novo mutant DAT-Asp421Asn, in an adult male with early-onset parkinsonism and ADHD. According to DAT single-photon emission computed tomography (DAT-SPECT) scans and a fluoro-deoxy-glucose-PET/MRI (FDG-PET/MRI) scan, the patient suffered from progressive dopaminergic neurodegeneration. In heterologous cells, both DAT variants exhibited markedly reduced dopamine uptake capacity but preserved membrane targeting, consistent with impaired catalytic activity. Computational simulations and uptake experiments suggested that the disrupted function of the DAT-Asp421Asn mutant is the result of compromised sodium binding, in agreement with Asp421 coordinating sodium at the second sodium site. For DAT-Asp421Asn, substrate efflux experiments revealed a constitutive, anomalous efflux of dopamine, and electrophysiological analyses identified a large cation leak that might further perturb dopaminergic neurotransmission. Our results link specific DAT missense mutations to neurodegenerative early-onset parkinsonism. Moreover, the neuropsychiatric comorbidity provides additional support for the idea that DAT missense mutations are an ADHD risk factor and suggests that complex DAT genotype and phenotype correlations contribute to different dopaminergic pathologies. PMID:24911152

  11. Missense Mutations in CRYAB Are Liable for Recessive Congenital Cataracts

    PubMed Central

    Irum, Bushra; Khan, Arif O.; Wang, Qiwei; Kabir, Firoz; Khan, Asma A.; Husnain, Tayyab; Akram, Javed; Riazuddin, Sheikh

    2015-01-01

    Purpose This study was initiated to identify causal mutations responsible for autosomal recessive congenital cataracts in consanguineous familial cases. Methods Affected individuals underwent a detailed ophthalmological and clinical examination, and slit-lamp photographs were ascertained for affected individuals who have not yet been operated for the removal of the cataractous lens. Blood samples were obtained, and genomic DNA was extracted from white blood cells. A genome-wide scan was completed with short tandem repeat (STR) markers, and the logarithm of odds (LOD) scores were calculated. Protein coding exons of CRYAB were sequenced, bi-directionally. Evolutionary conservation was investigated by aligning CRYAB orthologues, and the expression of Cryab in embryonic and postnatal mice lens was investigated with TaqMan probe. Results The clinical and ophthalmological examinations suggested that all affected individuals had nuclear cataracts. Genome-wide linkage analysis suggested a potential region on chromosome 11q23 harboring CRYAB. DNA sequencing identified a missense variation: c.34C>T (p.R12C) in CRYAB that segregated with the disease phenotype in the family. Subsequent interrogation of our entire cohort of familial cases identified a second familial case localized to chromosome 11q23 harboring a c.31C>T (p.R11C) mutation. In silico analyses suggested that the mutations identified in familial cases, p.R11C and p.R12C will not be tolerated by the three-dimensional structure of CRYAB. Real-time PCR analysis identified the expression of Cryab in mouse lens as early as embryonic day 15 (E15) that increased significantly until postnatal day 6 (P6) with steady level of expression thereafter. Conclusion Here, we report two novel missense mutations, p.R11C and p.R12C, in CRYAB associated with autosomal recessive congenital nuclear cataracts. PMID:26402864

  12. Missense Mutations in Fumarate Hydratase in Multiple Cutaneous and Uterine Leiomyomatosis and Renal Cell Cancer

    PubMed Central

    Alam, N. Afrina; Olpin, Simon; Rowan, Andrew; Kelsell, David; Leigh, Irene M.; Tomlinson, Ian P. M.; Weaver, Todd

    2005-01-01

    Heterozygous germline mutations in fumarate hydratase (FH) predispose to the multiple cutaneous and uterine leiomyomatosis syndrome (MCUL), which, when co-existing with renal cancer, is also known as hereditary leiomyomatosis and renal cell cancer. Twenty-seven distinct missense mutations represent 68% of FH mutations reported in MCUL. Here we show that FH missense mutations significantly occurred in fully conserved residues and in residues functioning in the FH A-site, B-site, or subunit-interacting region. Of 24 distinct missense mutations, 13 (54%) occurred in the substrate-binding A-site, 4 (17%) in the substrate-binding B-site, and 7 (29%) in the subunit-interacting region. Clustering of missense mutations suggested the presence of possible mutational hotspots. FH functional assay of lymphoblastoid cell lines from 23 individuals with heterozygous FH missense mutations showed that A-site mutants had significantly less residual activity than B-site mutants, supporting data from Escherichia coli that the A-site is the main catalytic site. Missense FH mutations predisposing to renal cancer had no unusual features, and identical mutations were found in families without renal cancer, suggesting a role for genetic or environmental factors in renal cancer development in MCUL. That all missense FH mutations associating with MCUL/hereditary leiomyomatosis and renal cell cancer showed diminished FH enzymatic activity suggests that the tumor suppressor role of fumarate hydratase may relate to its enzymatic function. PMID:16237213

  13. Drastic effect of germline TP53 missense mutations in Li-Fraumeni patients.

    PubMed

    Zerdoumi, Yasmine; Aury-Landas, Juliette; Bonaïti-Pellié, Catherine; Derambure, Céline; Sesboüé, Richard; Renaux-Petel, Mariette; Frebourg, Thierry; Bougeard, Gaëlle; Flaman, Jean-Michel

    2013-03-01

    In contrast to other tumor suppressor genes, the majority of TP53 alterations are missense mutations. We have previously reported that in the Li-Fraumeni syndrome (LFS), germline TP53 missense mutations are associated with an earlier age of tumor onset. In a larger series, we observed that mean age of tumor onset in patients harboring dominant negative missense mutations and clearly null mutations was 22.6 and 37.5 years, respectively. To assess the impact of heterozygous germline TP53 mutations in the genetic context of the patients, we developed a new functional assay of the p53 pathway on the basis of induction of DNA damage in Epstein-Barr-virus-immortalized lymphocytes, followed by comparative gene-expression profiling. In wild-type lymphocytes, we identified a core of 173 genes whose expression was induced more than twofold, of which 46 were known p53 target genes. In LFS lymphocytes with canonical missense mutations, the number of induced genes and the level of known p53 target genes induction were strongly reduced as compared with controls and LFS lymphocytes with null mutations. These results show that certain germline missense TP53 mutations, such as those with dominant negative effect, dramatically alter the response to DNA damage. This probably explains why TP53 alterations are predominantly missense mutations. PMID:23172776

  14. CanDrA: cancer-specific driver missense mutation annotation with optimized features.

    PubMed

    Mao, Yong; Chen, Han; Liang, Han; Meric-Bernstam, Funda; Mills, Gordon B; Chen, Ken

    2013-01-01

    Driver mutations are somatic mutations that provide growth advantage to tumor cells, while passenger mutations are those not functionally related to oncogenesis. Distinguishing drivers from passengers is challenging because drivers occur much less frequently than passengers, they tend to have low prevalence, their functions are multifactorial and not intuitively obvious. Missense mutations are excellent candidates as drivers, as they occur more frequently and are potentially easier to identify than other types of mutations. Although several methods have been developed for predicting the functional impact of missense mutations, only a few have been specifically designed for identifying driver mutations. As more mutations are being discovered, more accurate predictive models can be developed using machine learning approaches that systematically characterize the commonality and peculiarity of missense mutations under the background of specific cancer types. Here, we present a cancer driver annotation (CanDrA) tool that predicts missense driver mutations based on a set of 95 structural and evolutionary features computed by over 10 functional prediction algorithms such as CHASM, SIFT, and MutationAssessor. Through feature optimization and supervised training, CanDrA outperforms existing tools in analyzing the glioblastoma multiforme and ovarian carcinoma data sets in The Cancer Genome Atlas and the Cancer Cell Line Encyclopedia project. PMID:24205039

  15. An infant with MLH3 variants, FOXG1-duplication and multiple, benign cranial and spinal tumors: A clinical exome sequencing study.

    PubMed

    Kansal, Rina; Li, Xinmin; Shen, Joseph; Samuel, David; Laningham, Fred; Lee, Hane; Panigrahi, Gagan B; Shuen, Andrew; Kantarci, Sibel; Dorrani, Naghmeh; Reiss, Jean; Shintaku, Peter; Deignan, Joshua L; Strom, Samuel P; Pearson, Christopher E; Vilain, Eric; Grody, Wayne W

    2016-02-01

    A 4-month-old male infant presented with severe developmental delay, cerebellar, brainstem, and cutaneous hemangiomas, bilateral tumors (vestibular, hypoglossal, cervical, and lumbar spinal), and few café-au-lait macules. Cerebellar and lumbar tumor biopsies revealed venous telangiectasia and intraneural perineuroma, respectively. Sequencing NF1, NF2, and RASA1 (blood), and NF2 and SMARCB1 (lumbar biopsy) was negative for pathogenic mutations. Clinical exome sequencing (CES), requested for tumor syndrome diagnosis, revealed two heterozygous missense variants, c.359T>C;p.Phe120Ser and c.3344G>A;p.Arg1115Gln, in MLH3 (NM_001040108.1), a DNA mismatch repair (MMR) gene, Polyphen-predicted as probably damaging, and benign, respectively. Sanger sequencing confirmed both variants in the proband, and their absence in the mother; biological father unavailable. Both biopsied tissues were negative for microsatellite instability, and expressed MLH1, MSH2, PMS2, MSH6, and MLH3 immunohistochemically. Chromosomal microarray showed a 133 kb segment copy number duplication of 14q12 region encompassing FOXG1, possibly explaining the developmental delay, but not the tumors. The presence of MLH3 variants with multiple benign neural and vascular tumors was intriguing for their possible role in the pathogenesis of these neoplasms, which were suspicious for, but not diagnostic of, constitutional MMR deficiency. However, functional assays of non-neoplastic patient-derived cells showed intact base-base MMR function. Also, no previous FOXG1-aberrant patient was reported with tumors. We now report a 3-year-old FOXG1-duplicated patient with a yet undescribed tumor syndrome with clinical features of neurofibromatosis types I and II, where several validation studies could not ascertain the significance of CES findings; further studies may elucidate precise mechanisms and diagnosis for clinical management, including tumor surveillance. PMID:26542077

  16. HER2 missense mutations have distinct effects on oncogenic signaling and migration

    PubMed Central

    Zabransky, Daniel J.; Yankaskas, Christopher L.; Cochran, Rory L.; Wong, Hong Yuen; Croessmann, Sarah; Chu, David; Kavuri, Shyam M.; Red Brewer, Monica; Rosen, D. Marc; Dalton, W. Brian; Cimino-Mathews, Ashley; Cravero, Karen; Button, Berry; Kyker-Snowman, Kelly; Cidado, Justin; Erlanger, Bracha; Parsons, Heather A.; Manto, Kristen M.; Bose, Ron; Lauring, Josh; Arteaga, Carlos L.; Konstantopoulos, Konstantinos; Park, Ben Ho

    2015-01-01

    Recurrent human epidermal growth factor receptor 2 (HER2) missense mutations have been reported in human cancers. These mutations occur primarily in the absence of HER2 gene amplification such that most HER2-mutant tumors are classified as “negative” by FISH or immunohistochemistry assays. It remains unclear whether nonamplified HER2 missense mutations are oncogenic and whether they are targets for HER2-directed therapies that are currently approved for the treatment of HER2 gene-amplified breast cancers. Here we functionally characterize HER2 kinase and extracellular domain mutations through gene editing of the endogenous loci in HER2 nonamplified human breast epithelial cells. In in vitro and in vivo assays, the majority of HER2 missense mutations do not impart detectable oncogenic changes. However, the HER2 V777L mutation increased biochemical pathway activation and, in the context of a PIK3CA mutation, enhanced migratory features in vitro. However, the V777L mutation did not alter in vivo tumorigenicity or sensitivity to HER2-directed therapies in proliferation assays. Our results suggest the oncogenicity and potential targeting of HER2 missense mutations should be considered in the context of cooperating genetic alterations and provide previously unidentified insights into functional analysis of HER2 mutations and strategies to target them. PMID:26508629

  17. Cancer Missense Mutations Alter Binding Properties of Proteins and Their Interaction Networks

    PubMed Central

    Nishi, Hafumi; Tyagi, Manoj; Teng, Shaolei; Shoemaker, Benjamin A.; Hashimoto, Kosuke; Alexov, Emil; Wuchty, Stefan; Panchenko, Anna R.

    2013-01-01

    Many studies have shown that missense mutations might play an important role in carcinogenesis. However, the extent to which cancer mutations might affect biomolecular interactions remains unclear. Here, we map glioblastoma missense mutations on the human protein interactome, model the structures of affected protein complexes and decipher the effect of mutations on protein-protein, protein-nucleic acid and protein-ion binding interfaces. Although some missense mutations over-stabilize protein complexes, we found that the overall effect of mutations is destabilizing, mostly affecting the electrostatic component of binding energy. We also showed that mutations on interfaces resulted in more drastic changes of amino acid physico-chemical properties than mutations occurring outside the interfaces. Analysis of glioblastoma mutations on interfaces allowed us to stratify cancer-related interactions, identify potential driver genes, and propose two dozen additional cancer biomarkers, including those specific to functions of the nervous system. Such an analysis also offered insight into the molecular mechanism of the phenotypic outcomes of mutations, including effects on complex stability, activity, binding and turnover rate. As a result of mutated protein and gene network analysis, we observed that interactions of proteins with mutations mapped on interfaces had higher bottleneck properties compared to interactions with mutations elsewhere on the protein or unaffected interactions. Such observations suggest that genes with mutations directly affecting protein binding properties are preferably located in central network positions and may influence critical nodes and edges in signal transduction networks. PMID:23799087

  18. Molecular evaluation of a novel missense mutation & an insertional truncating mutation in SUMF1 gene

    PubMed Central

    Kotecha, Udhaya H.; Movva, Sireesha; Sharma, Deepak; Verma, Jyotsna; Puri, Ratna Dua; Verma, Ishwar Chander

    2014-01-01

    Background & objectives: Multiple suphphatase deficiency (MSD) is an autosomal recessive disorder affecting the post translational activation of all enzymes of the sulphatase family. To date, approximately 30 different mutations have been identified in the causative gene, sulfatase modifying factor 1 (SUMF1). We describe here the mutation analysis of a case of MSD. Methods: The proband was a four year old boy with developmental delay followed by neuroregression. He had coarse facies, appendicular hypertonia, truncal ataxia and ichthyosis limited to both lower limbs. Radiographs showed dysostosis multiplex. Clinical suspicion of MSD was confirmed by enzyme analysis of four enzymes of the sulphatase group. Results: The patient was compound heterozygote for a c.451A>G (p.K151E) substitution in exon 3 and a single base insertion mutation (c.690_691 InsT) in exon 5 in the SUMF1 gene. The bioinformatic analysis of the missense mutation revealed no apparent effect on the overall structure. However, the mutated 151-amino acid residue was found to be adjacent to the substrate binding and the active site residues, thereby affecting the substrate binding and/or catalytic activity, resulting in almost complete loss of enzyme function. Conclusions: The two mutations identified in the present case were novel. This is perhaps the first report of an insertion mutation in SUMF1 causing premature truncation of the protein. PMID:25222778

  19. Distal myopathy caused by homozygous missense mutations in the nebulin gene.

    PubMed

    Wallgren-Pettersson, Carina; Lehtokari, Vilma-Lotta; Kalimo, Hannu; Paetau, Anders; Nuutinen, Elina; Hackman, Peter; Sewry, Caroline; Pelin, Katarina; Udd, Bjarne

    2007-06-01

    We describe a novel, recessively inherited distal myopathy caused by homozygous missense mutations in the nebulin gene (NEB), in which other combinations of mutations are known to cause nemaline (rod) myopathy (NM). Two different missense mutations were identified in homozygous form in seven Finnish patients from four unrelated families with childhood or adult-onset foot drop. Both mutations, when combined in compound heterozygous form with more disruptive mutations in NEB, are known to cause NM. Hitherto, no patients with NM have been found to have two missense mutations in NEB. Muscle weakness predominantly affected ankle dorsiflexors, finger extensors and neck flexors, a distribution different both from the patterns of weakness seen in NM caused by NEB mutations, and those of the known recessively inherited distal myopathies. Singleton cases need to be distinguished from the Laing type of distal myopathy. Histologically, this myopathy differs from NM in that nemaline bodies were not detectable with routine light microscopy, and they were inconspicuous or absent even with electron microscopy. Rimmed vacuoles, commonly seen in other distal myopathies, were not a feature. We conclude that homozygous missense mutations in NEB cause a novel distal myopathy, predominantly involving lower leg extensor muscles, finger extensors and neck flexors. PMID:17525139

  20. Functional Characterization and Categorization of Missense Mutations that Cause Methylmalonyl‐CoA Mutase (MUT) Deficiency

    PubMed Central

    Forny, Patrick; Froese, D. Sean; Suormala, Terttu

    2014-01-01

    ABSTRACT Methylmalonyl‐CoA mutase (MUT) is an essential enzyme in propionate catabolism that requires adenosylcobalamin as a cofactor. Almost 250 inherited mutations in the MUT gene are known to cause the devastating disorder methylmalonic aciduria; however, the mechanism of dysfunction of these mutations, more than half of which are missense changes, has not been thoroughly investigated. Here, we examined 23 patient missense mutations covering a spectrum of exonic/structural regions, clinical phenotypes, and ethnic populations in order to determine their influence on protein stability, using two recombinant expression systems and a thermostability assay, and enzymatic function by measuring MUT activity and affinity for its cofactor and substrate. Our data stratify MUT missense mutations into categories of biochemical defects, including (1) reduced protein level due to misfolding, (2) increased thermolability, (3) impaired enzyme activity, and (4) reduced cofactor response in substrate turnover. We further demonstrate the stabilization of wild‐type and thermolabile mutants by chemical chaperones in vitro and in bacterial cells. This in‐depth mutation study illustrates the tools available for MUT enzyme characterization, guides future categorization of further missense mutations, and supports the development of alternative, chaperone‐based therapy for patients not responding to current treatment. PMID:25125334

  1. A patient with a novel homozygous missense mutation in FTO and concomitant nonsense mutation in CETP

    PubMed Central

    Çağlayan, Ahmet Okay; Tüysüz, Beyhan; Coşkun, Süleyman; Quon, Jennifer; Harmanci, Akdes Serin; Baranoski, Jacob F.; Baran, Burçin; Erson-Omay, E. Zeynep; Henegariu, Octavian; Mane, Shrikant M.; Bilgüvar, Kaya; Yasuno, Katsuhito; Günel, Murat

    2015-01-01

    The fat mass and obesity associated gene (FTO) has previously been associated with a variety of diseases and conditions, notably obesity, acute coronary syndrome and metabolic syndrome. Reports describing mutations in FTO as well as FTO animal models have further demonstrated a role for FTO in the development of the brain and other organs. Here, we describe a patient born of consanguineous union who presented with microcephaly, developmental delay, behavioral abnormalities, dysmorphic facial features, hypotonia, and other various phenotypic abnormalities. Whole exome sequencing revealed a novel homozygous missense mutation in FTO and a nonsense mutation in the cholesteryl ester transfer protein (CETP). Exome CNV analysis revealed no disease causing large duplications or deletions within coding regions. Patient’s, her parents’ and non-related control’ fibroblasts were analyzed for morphologic defects, abnormal proliferation, apoptosis and transcriptome profile. We have shown that FTO is located in nucleus of cells from each tested samples. Western blot analysis demonstrated no changes in patient FTO. Q-PCR analysis revealed slightly decreased levels of FTO expression in patient cells compared to controls. No morphological or proliferation differences between the patient and control fibroblasts were observed. There is still much to be learned about the molecular mechanisms by which mutations in FTO contribute to such severe phenotypes. PMID:26740239

  2. Reduced secretion and altered proteolytic processing caused by missense mutations in progranulin.

    PubMed

    Kleinberger, Gernot; Capell, Anja; Brouwers, Nathalie; Fellerer, Katrin; Sleegers, Kristel; Cruts, Marc; Van Broeckhoven, Christine; Haass, Christian

    2016-03-01

    Progranulin (GRN) is a secreted growth factor involved in various cellular functions, and loss-of-function mutations are a major cause of frontotemporal lobar degeneration (FTLD) with TDP-43 positive pathology. Most FTLD-related GRN mutations are nonsense mutations resulting in reduced GRN expression. Nonsynonymous GRN missense mutations have been described as risk factor for neurodegenerative brain diseases, but their pathogenic nature remains largely elusive. We identified a double missense mutation in GRN leading to amino acid changes p.D33E and p.G35R in an FTLD patient from Turkish origin. Biochemical and cell biological analysis of the double-mutation together with 2 so-far uncharacterized GRN missense mutations (p.C105R and p.V514M) revealed a reduced secretion efficiency of the GRN p.D33E/p.G35R and p.C105R proteins. Furthermore, loss of the conserved cysteine residue affects protein folding and altered proteolytic processing by neutrophil elastase and proteinase 3. Our data indicate that the described variants may cause a loss-of-function, albeit to a lesser extent than GRN null mutations, and hence could be considered as low-penetrant risk factors for neurodegenerative diseases. PMID:26811050

  3. First missense mutation outside of SERAC1 lipase domain affecting intracellular cholesterol trafficking.

    PubMed

    Rodríguez-García, María Elena; Martín-Hernández, Elena; de Aragón, Ana Martínez; García-Silva, María Teresa; Quijada-Fraile, Pilar; Arenas, Joaquín; Martín, Miguel A; Martínez-Azorín, Francisco

    2016-01-01

    We report the clinical and genetic findings in a Spanish boy who presented MEGDEL syndrome, a very rare inborn error of metabolism. Whole-exome sequencing uncovered a new homozygous mutation in the serine active site containing 1 (SERAC1) gene, which is essential for both mitochondrial function and intracellular cholesterol trafficking. Functional studies in patient fibroblasts showed that p.D224G mutation affects the intracellular cholesterol trafficking. Only three missense mutations in this gene have been described before, being p.D224G the first missense mutation outside of the SERAC1 serine-lipase domain. Therefore, we conclude that the defect in cholesterol trafficking is not limited to alterations in this specific part of the protein. PMID:26445863

  4. Very mild features of dysequilibrium syndrome associated with a novel VLDLR missense mutation.

    PubMed

    Micalizzi, Alessia; Moroni, Isabella; Ginevrino, Monia; Biagini, Tommaso; Mazza, Tommaso; Romani, Marta; Valente, Enza Maria

    2016-07-01

    Dysequilibrium syndrome (DES) is a non-progressive congenital ataxia characterized by severe intellectual deficit, truncal ataxia and markedly delayed, quadrupedal or absent ambulation. Recessive loss-of-function mutations in the very low density lipoprotein receptor (VLDLR) gene represent the most common cause of DES. Only two families have been reported harbouring homozygous missense mutations, both with a similarly severe phenotype. We report an Italian girl with very mild DES caused by the novel homozygous VLDLR missense mutation p.(C419Y). This unusually benign phenotype possibly relates to a less disruptive effect of the mutation, falling within a domain (EGF-B) not predicted as crucial for the protein function. PMID:27251579

  5. In silico investigation of molecular effects caused by missense mutations in creatine transporter protein

    NASA Astrophysics Data System (ADS)

    Zhang, Zhe; Schwatz, Charles; Alexov, Emil

    2011-03-01

    Creatine transporter (CT) protein, which is encoded by SLC6A8 gene, is essential for taking up the creatine in the cell, which in turn plays a key role in the spatial and temporal maintenance of energy in skeletal and cardiac muscle cells. It was shown that some missense mutations in CT cause mental retardation, while others are harmless non-synonymous single nucleoside polymorphism (nsSNP). Currently fifteen missense mutations in CT are known, among which twelve are disease-causing. Sequence analysis reveals that there is no clear trend distinguishing disease-causing from harmless missense mutations. Because of that, we built 3D model of the CT using highly homologous template and use the model to investigate the effects of mutations of CT stability and hydrogen bond network. It is demonstrated that disease-causing mutations affect the folding free energy and ionization states of titratable group in much greater extend as compared with harmless mutations. Supported by grants from NLM, NIH, grant numbers 1R03LM009748 and 1R03LM009748-S1.

  6. Gene Coexpression Analyses Differentiate Networks Associated with Diverse Cancers Harboring TP53 Missense or Null Mutations

    PubMed Central

    Oros Klein, Kathleen; Oualkacha, Karim; Lafond, Marie-Hélène; Bhatnagar, Sahir; Tonin, Patricia N.; Greenwood, Celia M. T.

    2016-01-01

    In a variety of solid cancers, missense mutations in the well-established TP53 tumor suppressor gene may lead to the presence of a partially-functioning protein molecule, whereas mutations affecting the protein encoding reading frame, often referred to as null mutations, result in the absence of p53 protein. Both types of mutations have been observed in the same cancer type. As the resulting tumor biology may be quite different between these two groups, we used RNA-sequencing data from The Cancer Genome Atlas (TCGA) from four different cancers with poor prognosis, namely ovarian, breast, lung and skin cancers, to compare the patterns of coexpression of genes in tumors grouped according to their TP53 missense or null mutation status. We used Weighted Gene Coexpression Network analysis (WGCNA) and a new test statistic built on differences between groups in the measures of gene connectivity. For each cancer, our analysis identified a set of genes showing differential coexpression patterns between the TP53 missense- and null mutation-carrying groups that was robust to the choice of the tuning parameter in WGCNA. After comparing these sets of genes across the four cancers, one gene (KIR3DL2) consistently showed differential coexpression patterns between the null and missense groups. KIR3DL2 is known to play an important role in regulating the immune response, which is consistent with our observation that this gene's strongly-correlated partners implicated many immune-related pathways. Examining mutation-type-related changes in correlations between sets of genes may provide new insight into tumor biology. PMID:27536319

  7. Characterization of a Spontaneous, Recessive, Missense Mutation Arising in the Tecta Gene

    PubMed Central

    Goodyear, Richard J.; Mencía, Angeles; Modamio-Høybjør, Silvia; Legan, P. Kevin; Olavarrieta, Leticia; Moreno, Felipe; Richardson, Guy P.

    2008-01-01

    The TECTA gene encodes alpha-tectorin (TECTA), a major noncollagenous component of the tectorial membrane (TM). In humans, mutations in TECTA lead to either dominant (DFNA8/A12) or recessive (DFNB21) forms of nonsyndromic hearing loss. All missense mutations in TECTA that have been reported thus far are associated with the dominant subtype, whereas those leading to recessive deafness are all inactivating mutations. In this paper, we characterize a spontaneous missense mutation (c.1046C > A, p.A349D) arising in the mouse Tecta gene that is, unlike all previously reported missense mutations in TECTA, recessive. The morphological phenotype of the TectaA349D/A349D mouse resembles but is not identical to that previously described for the \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Tecta^{{{\\Delta {\\text{ENT}}} \\mathord{\\left/ {\\vphantom {{\\Delta {\\text{ENT}}} {\\Delta {\\text{ENT}}}}} \\right. \\kern-\

  8. Identification and functional analysis of SOX10 missense mutations in different subtypes of Waardenburg syndrome.

    PubMed

    Chaoui, Asma; Watanabe, Yuli; Touraine, Renaud; Baral, Viviane; Goossens, Michel; Pingault, Veronique; Bondurand, Nadege

    2011-12-01

    Waardenburg syndrome (WS) is a rare disorder characterized by pigmentation defects and sensorineural deafness, classified into four clinical subtypes, WS1-S4. Whereas the absence of additional features characterizes WS2, association with Hirschsprung disease defines WS4. WS is genetically heterogeneous, with six genes already identified, including SOX10. About 50 heterozygous SOX10 mutations have been described in patients presenting with WS2 or WS4, with or without myelination defects of the peripheral and central nervous system (PCWH, Peripheral demyelinating neuropathy-Central dysmyelinating leukodystrophy-Waardenburg syndrome-Hirschsprung disease, or PCW, PCWH without HD). The majority are truncating mutations that most often remove the main functional domains of the protein. Only three missense mutations have been thus far reported. In the present study, novel SOX10 missense mutations were found in 11 patients and were examined for effects on SOX10 characteristics and functions. The mutations were associated with various phenotypes, ranging from WS2 to PCWH. All tested mutations were found to be deleterious. Some mutants presented with partial cytoplasmic redistribution, some lost their DNA-binding and/or transactivation capabilities on various tissue-specific target genes. Intriguingly, several mutants were redistributed in nuclear foci. Whether this phenomenon is a cause or a consequence of mutation-associated pathogenicity remains to be determined, but this observation could help to identify new SOX10 modes of action. PMID:21898658

  9. Predicting the Impact of Missense Mutations on Protein-Protein Binding Affinity.

    PubMed

    Li, Minghui; Petukh, Marharyta; Alexov, Emil; Panchenko, Anna R

    2014-04-01

    The crucial prerequisite for proper biological function is the protein's ability to establish highly selective interactions with macromolecular partners. A missense mutation that alters the protein binding affinity may cause significant perturbations or complete abolishment of the function, potentially leading to diseases. The availability of computational methods to evaluate the impact of mutations on protein-protein binding is critical for a wide range of biomedical applications. Here, we report an efficient computational approach for predicting the effect of single and multiple missense mutations on protein-protein binding affinity. It is based on a well-tested simulation protocol for structure minimization, modified MM-PBSA and statistical scoring energy functions with parameters optimized on experimental sets of several thousands of mutations. Our simulation protocol yields very good agreement between predicted and experimental values with Pearson correlation coefficients of 0.69 and 0.63 and root-mean-square errors of 1.20 and 1.90 kcal mol(-1) for single and multiple mutations, respectively. Compared with other available methods, our approach achieves high speed and prediction accuracy and can be applied to large datasets generated by modern genomics initiatives. In addition, we report a crucial role of water model and the polar solvation energy in estimating the changes in binding affinity. Our analysis also reveals that prediction accuracy and effect of mutations on binding strongly depends on the type of mutation and its location in a protein complex. PMID:24803870

  10. Recessive Osteogenesis Imperfecta Caused by Missense Mutations in SPARC

    PubMed Central

    Mendoza-Londono, Roberto; Fahiminiya, Somayyeh; Majewski, Jacek; Tétreault, Martine; Nadaf, Javad; Kannu, Peter; Sochett, Etienne; Howard, Andrew; Stimec, Jennifer; Dupuis, Lucie; Roschger, Paul; Klaushofer, Klaus; Palomo, Telma; Ouellet, Jean; Al-Jallad, Hadil; Mort, John S.; Moffatt, Pierre; Boudko, Sergei; Bächinger, Hans-Peter; Rauch, Frank

    2015-01-01

    Secreted protein, acidic, cysteine-rich (SPARC) is a glycoprotein that binds to collagen type I and other proteins in the extracellular matrix. Using whole-exome sequencing to identify the molecular defect in two unrelated girls with severe bone fragility and a clinical diagnosis of osteogenesis imperfecta type IV, we identified two homozygous variants in SPARC (GenBank: NM_003118.3; c.497G>A [p.Arg166His] in individual 1; c.787G>A [p.Glu263Lys] in individual 2). Published modeling and site-directed mutagenesis studies had previously shown that the residues substituted by these mutations form an intramolecular salt bridge in SPARC and are essential for the binding of SPARC to collagen type I. The amount of SPARC secreted by skin fibroblasts was reduced in individual 1 but appeared normal in individual 2. The migration of collagen type I alpha chains produced by these fibroblasts was mildly delayed on SDS-PAGE gel, suggesting some overmodification of collagen during triple helical formation. Pulse-chase experiments showed that collagen type I secretion was mildly delayed in skin fibroblasts from both individuals. Analysis of an iliac bone sample from individual 2 showed that trabecular bone was hypermineralized on the material level. In conclusion, these observations show that homozygous mutations in SPARC can give rise to severe bone fragility in humans. PMID:26027498

  11. Dyskeratosis congenita--two siblings with a new missense mutation in the DKC1 gene.

    PubMed

    Coelho, Joana Dias; Lestre, Sara; Kay, Teresa; Lopes, Maria João Paiva; Fiadeiro, Teresa; Apetato, Margarida

    2011-01-01

    Dyskeratosis congenital is reported in two siblings. They presented with the classic triad of mucocutaneous features: leukoplakia of the tongue, dystrophic nails, and a widespread reticulate pigmentation on the neck and upper chest. A genetic analysis was performed and a new missense mutation S356P, hemizygous, was identified in the DKC1 gene in both patients. Acitretin was started at a low-dose in both patients, resulting in clinical improvement and important, positive psychosocial effects. PMID:21736606

  12. Theoretical prediction of familial amyotrophic lateral sclerosis missense mutation effects on Cu/Zn superoxide dismutase structural stability

    SciTech Connect

    Potier, M.; Tu, Y.

    1994-09-01

    Cu/Zn superoxide dismutase (SOD) deficiency is associated with the progressive paralytic disorder familial amyotrophic lateral sclerosis (FALS). Fifteen missense mutations in the SOD gene were identified in several patients. These mutations may prevent correct promoter folding or hamper homodimer formation necessary for SOD activity. To understand the effect of the missense mutations on SOD structure and function, we used a theoretical analysis of structural effects based on two predictive methods using the modeled tertiary structure of human SOD. The first method uses the TORSO program which optimizes amino acid side-chains repacking in both wild-type and mutant SODs and calculates protein internal packing energy. The second method uses a hydrophobicity scale of the amino acid residues and considers both solvent accessibility and hydrophobic nature of residue substitutions to compute a stabilization energy change ({delta}E). These predictive methods have been tested in 187 single and multiple missense mutants of 8 proteins (T4 lysozyme, human carbonic anhydrase II, chymotrypsin inhibitor 2, f1 gene V protein, barnase, {lambda}-repressor, chicken and human lysozymes) with experimentally determined thermostability. The overall prediction accuracy with these proteins was 88%. Analysis of FALS missense mutations {delta}E predicts that 14 of 15 mutations destabilize the SOD structure. The other missense mutation is located at the homodimer interface and may hinder dimer formation. This approach is applicable to any protein with known tertiary structure to predict missense mutation effects on protein stability.

  13. The ZZ domain of dystrophin in DMD: making sense of missense mutations.

    PubMed

    Vulin, Adeline; Wein, Nicolas; Strandjord, Dana M; Johnson, Eric K; Findlay, Andrew R; Maiti, Baijayanta; Howard, Michael T; Kaminoh, Yuuki J; Taylor, Laura E; Simmons, Tabatha R; Ray, Will C; Montanaro, Federica; Ervasti, Jim M; Flanigan, Kevin M

    2014-02-01

    Duchenne muscular dystrophy (DMD) is associated with the loss of dystrophin, which plays an important role in myofiber integrity via interactions with β-dystroglycan and other members of the transmembrane dystrophin-associated protein complex. The ZZ domain, a cysteine-rich zinc-finger domain near the dystrophin C-terminus, is implicated in forming a stable interaction between dystrophin and β-dystroglycan, but the mechanism of pathogenesis of ZZ missense mutations has remained unclear because not all such mutations have been shown to alter β-dystroglycan binding in previous experimental systems. We engineered three ZZ mutations (p.Cys3313Phe, p.Asp3335His, and p.Cys3340Tyr) into a short construct similar to the Dp71 dystrophin isoform for in vitro and in vivo studies and delineated their effect on protein expression, folding properties, and binding partners. Our results demonstrate two distinct pathogenic mechanisms for ZZ missense mutations. The cysteine mutations result in diminished or absent subsarcolemmal expression because of protein instability, likely due to misfolding. In contrast, the aspartic acid mutation disrupts binding with β-dystroglycan despite an almost normal expression at the membrane, confirming a role for the ZZ domain in β-dystroglycan binding but surprisingly demonstrating that such binding is not required for subsarcolemmal localization of dystrophin, even in the absence of actin binding domains. PMID:24302611

  14. Structural variation and missense mutation in SBDS associated with Shwachman-Diamond syndrome

    PubMed Central

    2014-01-01

    Background Shwachman–Diamond syndrome (SDS) is an autosomal recessive ribosomopathy caused mainly by compound heterozygous mutations in SBDS. Structural variation (SV) involving the SBDS locus has been rarely reported in association with the disease. We aimed to determine whether an SV contributed to the pathogenesis of a case lacking biallelic SBDS point mutations. Case presentation Whole exome sequencing was performed in a patient with SDS lacking biallelic SBDS point mutations. Array comparative genomic hybridization and Southern blotting were used to seek SVs across the SBDS locus. Locus-specific polymerase chain reaction (PCR) encompassing flanking intronic sequence was also performed to investigate mutation within the locus. RNA expression and Western blotting were performed to analyze allele and protein expression. We found the child harbored a single missense mutation in SBDS (c.98A > C; p.K33T), inherited from the mother, and an SV in the SBDS locus, inherited from the father. The missense allele and SV segregated in accordance with Mendelian expectations for autosomal recessive SDS. Complementary DNA and western blotting analysis and locus specific PCR support the contention that the SV perturbed SBDS protein expression in the father and child. Conclusion Our findings implicate genomic rearrangements in the pathogenesis of some cases of SDS and support patients lacking biallelic SBDS point mutations be tested for SV within the SBDS locus. PMID:24898207

  15. A novel missense mutation in POMT1 modulates the severe congenital muscular dystrophy phenotype associated with POMT1 nonsense mutations.

    PubMed

    Wallace, Stephanie E; Conta, Jessie H; Winder, Thomas L; Willer, Tobias; Eskuri, Jamie M; Haas, Richard; Patterson, Kathleen; Campbell, Kevin P; Moore, Steven A; Gospe, Sidney M

    2014-04-01

    Mutations in POMT1 lead to a group of neuromuscular conditions ranging in severity from Walker-Warburg syndrome to limb girdle muscular dystrophy. We report two male siblings, ages 19 and 14, and an unrelated 6-year old female with early onset muscular dystrophy and intellectual disability with minimal structural brain anomalies and no ocular abnormalities. Compound heterozygous mutations in POMT1 were identified including a previously reported nonsense mutation (c.2167dupG; p.Asp723Glyfs*8) associated with Walker-Warburg syndrome and a novel missense mutation in a highly conserved region of the protein O-mannosyltransferase 1 protein (c.1958C>T; p.Pro653Leu). This novel variant reduces the phenotypic severity compared to patients with homozygous c.2167dupG mutations or compound heterozygous patients with a c.2167dupG mutation and a wide range of other mutant POMT1 alleles. PMID:24491487

  16. A Novel Missense Mutation in POMT1 Modulates the Severe Congenital Muscular Dystrophy Phenotype Associated with POMT1 Nonsense Mutations

    PubMed Central

    Wallace, Stephanie E.; Conta, Jessie H.; Winder, Thomas L.; Willer, Tobias; Eskuri, Jamie M.; Haas, Richard; Patterson, Kathleen; Campbell, Kevin P.; Moore, Steven A.; Gospe, Sidney M.

    2014-01-01

    Mutations in POMT1 lead to a group of neuromuscular conditions ranging in severity from Walker-Warburg syndrome to limb girdle muscular dystrophy. We report two male siblings, ages 19 and 14, and an unrelated 6-year old female with early onset muscular dystrophy and intellectual disability with minimal structural brain anomalies and no ocular abnormalities. Compound heterozygous mutations in POMT1 were identified including a previously reported nonsense mutation (c.2167dupG; p.Asp723Glyfs*8) associated with Walker-Warburg syndrome and a novel missense mutation in a highly conserved region of the protein O-mannosyltransferase 1 protein (c.1958C>T; p.Pro653Leu). This novel variant reduces the phenotypic severity compared to patients with homozygous c.2167dupG mutations or compound heterozygous patients with a c.2167dupG mutation and a wide range of other mutant POMT1 alleles. PMID:24491487

  17. In silico analyses of missense mutations in coagulation factor VIII: identification of severity determinants of haemophilia A.

    PubMed

    Sengupta, M; Sarkar, D; Ganguly, K; Sengupta, D; Bhaskar, S; Ray, K

    2015-09-01

    Factor VIII (FVIII) mutations cause haemophilia A (HA), an X-linked recessive coagulation disorder. Over 1000 missense mutations in FVIII are known and they lead to variable clinical phenotypes (severe, moderate and mild). The exact molecular basis of this phenotypic heterogeneity by FVIII missense mutations is elusive to date. In this study, we aimed to identify the severity determinants that cause phenotypic heterogeneity of HA. We compiled and curated a data set of 766 missense mutations from the repertoire of missense mutations in FVIII. We analysed these mutations by computational programs (e.g. Swiss-PdbViewer) and different mutation analysis servers (e.g. SIFT, PROVEAN, CUPSAT, PolyPhen2, MutPred); and various sequence- and structure-based parameters were assessed for any significant distribution bias among different HA phenotypes. Our analyses suggest that 'mutations in evolutionary conserved residues', 'mutations in buried residues', mutation-induced 'steric clash' and 'surface electrostatic potential alteration' act as risk factors towards severe HA. We have developed a grading system for FVIII mutations combining the severity determinants, and the grading pattern correlates with HA phenotype. This study will help to correctly associate the HA phenotype with a mutation and aid early characterization of novel variants. PMID:25854144

  18. Proteasomal Inhibition Restores Biological Function of Mis-sense Mutated Dysferlin in Patient-derived Muscle Cells*

    PubMed Central

    Azakir, Bilal A.; Di Fulvio, Sabrina; Kinter, Jochen; Sinnreich, Michael

    2012-01-01

    Dysferlin is a transmembrane protein implicated in surface membrane repair of muscle cells. Mutations in dysferlin cause the progressive muscular dystrophies Miyoshi myopathy, limb girdle muscular dystrophy 2B, and distal anterior compartment myopathy. Dysferlinopathies are inherited in an autosomal recessive manner, and many patients with this disease harbor mis-sense mutations in at least one of their two pathogenic DYSF alleles. These patients have significantly reduced or absent dysferlin levels in skeletal muscle, suggesting that dysferlin encoded by mis-sense alleles is rapidly degraded by the cellular quality control system. We reasoned that mis-sense mutated dysferlin, if salvaged from degradation, might be biologically functional. We used a dysferlin-deficient human myoblast culture harboring the common R555W mis-sense allele and a DYSF-null allele, as well as control human myoblast cultures harboring either two wild-type or two null alleles. We measured dysferlin protein and mRNA levels, resealing kinetics of laser-induced plasmalemmal wounds, myotube formation, and cellular viability after treatment of the human myoblast cultures with the proteasome inhibitors lactacystin or bortezomib (Velcade). We show that endogenous R555W mis-sense mutated dysferlin is degraded by the proteasomal system. Inhibition of the proteasome by lactacystin or Velcade increases the levels of R555W mis-sense mutated dysferlin. This salvaged protein is functional as it restores plasma membrane resealing in patient-derived myoblasts and reverses their deficit in myotube formation. Bortezomib and lactacystin did not cause cellular toxicity at the regimen used. Our results raise the possibility that inhibition of the degradation pathway of mis-sense mutated dysferlin could be used as a therapeutic strategy for patients harboring certain dysferlin mis-sense mutations. PMID:22318734

  19. Missense mutation (E150K) of rhodopsin in autosomal recessive retinitis pigmentosa

    SciTech Connect

    Orth, U.; Oehlmann, R.; Gal, A.

    1994-09-01

    Missense or nonsense mutations of the rhodopsin gene have been implied in the pathogenesis of at least 3 different traits; autosomal dominant retinitis pigmentosa (adRP), congenital stationary night blindness (CSNB), and autosomal recessive retinitis pigmentosa (arRP). For the latter, a single patient has been reported with a nonsense mutation at codon 249 on both alleles. Heterozygous carriers of missense mutations of rhodopsin develop either adRP or CSNB depending on the particular amino acid substitution. Four of the 9 siblings from a consanguineous marriage in southern India were reported the have arRP. Mutational screening and sequencing of the rhodopsin gene revealed a G-to-A transition of the first nucleotide at codon 150 in exon II, which alters glutamate to lysine. The E150K mutation was present in the 4 patients in homozygous form, whereas the parents and 2 of the siblings were heterozygotes. Two-point analysis produced a Zmax=3.46 at theta=0.00. Two unaffected siblings who are heterozygotes for the E150K mutation underwent a thorough ophthalmological and psychophysical examination. No clinical abnormalities were found although these individuals were over forty, whereas the onset of RP in their affected siblings was in the second decade. Collectively, both the genetic and clinical findings strongly suggest that the E150K mutation of rhodopsin is recessive in this family. Glu150 forms part of the CD cytoplasmic loop of rhodopsin, which has been implicated in the binding and activation of transducin. We speculate that E150K leads to RP because the mutant protein may be incapable of activating transducin. It is tempting to speculate that, in addition to mutations in the genes for rhodopsin and the {beta}-subunit of PDE, mutations in the genes for transducin may also result in arRP.

  20. MECP2 missense mutations outside the canonical MBD and TRD domains in males with intellectual disability.

    PubMed

    Bianciardi, Laura; Fichera, Marco; Failla, Pinella; Di Marco, Chiara; Grozeva, Detelina; Mencarelli, Maria Antonietta; Spiga, Ottavia; Mari, Francesca; Meloni, Ilaria; Raymond, Lucy; Renieri, Alessandra; Romano, Corrado; Ariani, Francesca

    2016-02-01

    Methyl-CpG-binding protein 2 (MeCP2) is a nuclear protein highly expressed in neurons that is involved in transcriptional modulation and chromatin remodeling. Mutations in MECP2 in females are associated with Rett syndrome, a neurological disorder characterized by a normal neonatal period, followed by the arrest of development and regression of acquired skills. Although it was initially thought that MECP2 pathogenic mutations in males were not compatible with life, starting from 1999 about 60 male patients have been identified and their phenotype varies from severe neonatal encephalopathy to mild intellectual disability. Targeted next-generation sequencing of a panel of intellectual disability related genes was performed on two unrelated male patients, and two missense variants in MECP2 were identified (p.Gly185Val and p.Arg167Trp). These variants lie outside the canonical methyl-CpG-binding domain and transcription repression domain domains, where the pathogenicity of missense variants is more difficult to establish. In both families, variants were found in all affected siblings and were inherited from the asymptomatic mother, showing skewed X-chromosome inactivation. We report here the first missense variant located in AT-hook domain 1 and we underline the importance of MECP2 substitutions outside the canonical MeCP2 domains in X-linked intellectual disability. PMID:26490184

  1. MECP2 missense mutations outside the canonical MBD and TRD domains in males with intellectual disability

    PubMed Central

    Failla, Pinella; Di Marco, Chiara; Grozeva, Detelina; Mencarelli, Maria Antonietta; Spiga, Ottavia; Mari, Francesca; Meloni, Ilaria; Raymond, Lucy; Renieri, Alessandra; Romano, Corrado; Ariani, Francesca

    2015-01-01

    Methyl-CpG binding protein 2 (MeCP2) is a nuclear protein highly expressed in neurons that is involved in transcriptional modulation and chromatin remodeling. Mutations in MECP2 in females are associated with Rett syndrome, a neurological disorder characterized by a normal neonatal period, followed by the arrest of development and regression of acquired skills. Although it was initially thought that MECP2 pathogenic mutations in males were not compatible with life, starting from 1999 about 60 male patients have been identified and their phenotype varies from severe neonatal encephalopathy to mild intellectual disability. Targeted Next Generation Sequencing of a panel of intellectual disability related genes was performed on two unrelated male patients, and two missense variants in MECP2 were identified (p.Gly185Val and p.Arg167Trp). These variants lie outside the canonical MBD and TRD domains, where the pathogenicity of missense variants is more difficult to establish. In both families, variants were found in all affected siblings and were inherited from the asymptomatic mother, showing skewed X-chromosome inactivation. We report here the first missense variant located in AT-hook domain 1 and we underline the importance of MECP2 substitutions outside the canonical MeCP2 domains in X-linked intellectual disability. PMID:26490184

  2. Extending the mutation spectrum for Galloway-Mowat syndrome to include homozygous missense mutations in the WDR73 gene.

    PubMed

    Rosti, Rasim O; Dikoglu, Esra; Zaki, Maha S; Abdel-Salam, Ghada; Makhseed, Nawal; Sese, Jordan C; Musaev, Damir; Rosti, Basak; Harbert, Mary J; Jones, Marilyn C; Vaux, Keith K; Gleeson, Joseph G

    2016-04-01

    Galloway-Mowat syndrome is a rare autosomal-recessive disorder classically described as the combination of microcephaly and nephrotic syndrome. Recently, homozygous truncating mutations in WDR73 (WD repeat domain 73) were described in two of 31 unrelated families with Galloway-Mowat syndrome which was followed by a report of two sibs in an Egyptian consanguineous family. In this report, seven affecteds from four families showing biallelic missense mutations in WDR73 were identified by exome sequencing and confirmed to follow a recessive model of inheritance. Three-dimensional modeling predicted conformational alterations as a result of the mutation, supporting pathogenicity. An additional 13 families with microcephaly and renal phenotype were negative for WDR73 mutations. Missense mutations in the WDR73 gene are reported for the first time in Galloway-Mowat syndrome. A detailed phenotypic comparison of all reported WDR73-linked Galloway-Mowat syndrome patients with WDR73 negative patients showed that WDR73 mutations are limited to those with classical Galloway-Mowat syndrome features, in addition to cerebellar atrophy, thin corpus callosum, brain stem hypoplasia, occasional coarse face, late-onset and mostly slow progressive nephrotic syndrome, and frequent epilepsy. PMID:27001912

  3. Extending the Mutation Spectrum for Galloway–Mowat Syndrome to Include Homozygous Missense Mutations in the WDR73 Gene

    PubMed Central

    Rosti, Rasim O.; Dikoglu, Esra; Zaki, Maha S.; Abdel-Salam, Ghada; Makhseed, Nawal; Sese, Jordan C.; Musaev, Damir; Rosti, Basak; Harbert, Mary J.; Jones, Marilyn C.; Vaux, Keith K.; Gleeson, Joseph G.

    2016-01-01

    Galloway–Mowat syndrome is a rare autosomal-recessive disorder classically described as the combination of microcephaly and nephrotic syndrome. Recently, homozygous truncating mutations in WDR73 (WD repeat domain 73) were described in two of 31 unrelated families with Galloway–Mowat syndrome which was followed by a report of two sibs in an Egyptian consanguineous family. In this report, seven affecteds from four families showing biallelic missense mutations in WDR73 were identified by exome sequencing and confirmed to follow a recessive model of inheritance. Three-dimensional modeling predicted conformational alterations as a result of the mutation, supporting pathogenicity. An additional 13 families with microcephaly and renal phenotype were negative for WDR73 mutations. Missense mutations in the WDR73 gene are reported for the first time in Galloway–Mowat syndrome. A detailed phenotypic comparison of all reported WDR73-linked Galloway–Mowat syndrome patients with WDR73 negative patients showed that WDR73 mutations are limited to those with classical Galloway–Mowat syndrome features, in addition to cerebellar atrophy, thin corpus callosum, brain stem hypoplasia, occasional coarse face, late-onset and mostly slow progressive nephrotic syndrome, and frequent epilepsy. PMID:27001912

  4. A Novel Missense Mutation in CLCN1 Gene in a Family with Autosomal Recessive Congenital Myotonia.

    PubMed

    Miryounesi, Mohammad; Ghafouri-Fard, Soudeh; Fardaei, Majid

    2016-09-01

    Congenital recessive myotonia is a rare genetic disorder caused by mutations in CLCN1, which codes for the main skeletal muscle chloride channel ClC-1. More than 120 mutations have been found in this gene. The main feature of this disorder is muscle membrane hyperexcitability. Here, we report a 59-year male patient suffering from congenital myotonia. He had transient generalized myotonia, which started in early childhood. We analyzed CLCN1 sequence in this patient and other members of his family. We found a new missense mutation in CLCN1 gene (c.1886T>C, p.Leu629Pro). Co-segregation of this mutation with the disease was demonstrated by direct sequencing of the fragment in affected as well as unaffected members of this family. In addition, in silico analyses predicted that this nucleotide change would impair the protein function. Thus, this new nucleotide variation can be used for prenatal diagnosis in this family. PMID:27582597

  5. Intrafamilial phenotypic heterogeneity of epidermolytic ichthyosis associated with a new missense mutation in keratin 10.

    PubMed

    Abdul-Wahab, A; Takeichi, T; Liu, L; Stephens, C; Akiyama, M; McGrath, J A

    2016-04-01

    Mutations in the keratin 10 gene (KRT10) have been shown to underlie several forms of epidermolytic ichthyosis (EI), including generalized, annular and naevoid variants. We investigated an autosomal dominant pedigree with ichthyosis in which there was intrafamilial clinical heterogeneity, with the affected individual family members presenting with features of either erythrokeratoderma progressiva, annular EI, localized or superficial EI, or more generalized EI. Sanger sequencing identified a new heterozygous missense mutation (c.457C>A; p.Leu153Met) in KRT10 in all affected individuals. No additional mutations were identified in the genes for keratin 1 (KRT1) keratin 2 (KRT2), connexin 31 (GJB3) or connexin 30.3 (GJB4) that might account for the clinical heterogeneity seen in this family. Our findings illustrate the intrafamilial variability in phenotype and diverse clinical presentations that can occur in EI resulting from a single mutation in KRT10. PMID:26338057

  6. A Novel Missense Mutation in CLCN1 Gene in a Family with Autosomal Recessive Congenital Myotonia

    PubMed Central

    Miryounesi, Mohammad; Ghafouri-Fard, Soudeh; Fardaei, Majid

    2016-01-01

    Congenital recessive myotonia is a rare genetic disorder caused by mutations in CLCN1, which codes for the main skeletal muscle chloride channel ClC-1. More than 120 mutations have been found in this gene. The main feature of this disorder is muscle membrane hyperexcitability. Here, we report a 59-year male patient suffering from congenital myotonia. He had transient generalized myotonia, which started in early childhood. We analyzed CLCN1 sequence in this patient and other members of his family. We found a new missense mutation in CLCN1 gene (c.1886T>C, p.Leu629Pro). Co-segregation of this mutation with the disease was demonstrated by direct sequencing of the fragment in affected as well as unaffected members of this family. In addition, in silico analyses predicted that this nucleotide change would impair the protein function. Thus, this new nucleotide variation can be used for prenatal diagnosis in this family. PMID:27582597

  7. Novel missense mutation in the FH gene in familial renal cell cancer patients lacking cutaneous leiomyomas

    PubMed Central

    2014-01-01

    Background Hereditary leiomyomatosis and renal cell cancer (HLRCC) is a rare tumor predisposition syndrome characterized by cutaneous and uterine leiomyomas and papillary type 2 renal cell cancer. Germline mutation of the fumarate hydratase (FH) gene is known to be associated with HLRCC. Case presentation We describe a 64-year-old father and his 39-year-old son with HLRCC who developed papillary type 2 RCCs lacking cutaneous leiomyomas at any site. A common missense mutation in the FH gene, (c.1021G > A, p.D341N) in exon 7, was detected in the 2 cases. Functional prediction with the bioinformatics programs, SIFT and Polyphen-2, reported “damaging (SIFT score 0.00)” and “probably damaging (PSIC score 1.621)” values, respectively. In 162 healthy individuals, there were no cases of a G transition to any base. Finally, (c.1021G > A) in exon 7, was identified as a point mutation. Conclusion We report a family with HLRCC in which a novel missense mutation was detected. A familial papillary type 2 renal cancer should be considered HLRCC unless typical cutaneous leiomyomas do not occur. PMID:24684806

  8. Effects of mutations at position 36 of tRNA(Glu) on missense and nonsense suppression in Escherichia coli.

    PubMed

    Gregory, S T; Dahlberg, A E

    1995-03-13

    Mutations in the anticodon of tRNA(Glu) (UUC) were isolated or constructed and characterized for their ability to suppress cognate nonsense or missense mutations in vivo. The C36-to-A36 transversion mutation was isolated as an ochre and an amber suppressor, while the G36 transversion was selected as a CAG missense suppressor. tRNA(Glu) suppressors of an AAG missense mutation could not be isolated, and a U36 transition mutation introduced into tRNA(Glu) in vitro conferred no suppressor phenotype. Over-expression of glutamyl-tRNA synthetase did not increase the activity of the U36 mutant tRNA(Glu), suggesting a defect at the level of translation rather than at the level of synthetase recognition. PMID:7890035

  9. A Novel Autosomal Recessive GJA1 Missense Mutation Linked to Craniometaphyseal Dysplasia

    PubMed Central

    Hu, Ying; Chen, I-Ping; de Almeida, Salome; Tiziani, Valdenize; Do Amaral, Cassio M. Raposo; Gowrishankar, Kalpana; Passos-Bueno, Maria Rita; Reichenberger, Ernst J.

    2013-01-01

    Craniometaphyseal dysplasia (CMD) is a rare sclerosing skeletal disorder with progressive hyperostosis of craniofacial bones. CMD can be inherited in an autosomal dominant (AD) trait or occur after de novo mutations in the pyrophosphate transporter ANKH. Although the autosomal recessive (AR) form of CMD had been mapped to 6q21-22 the mutation has been elusive. In this study, we performed whole-exome sequencing for one subject with AR CMD and identified a novel missense mutation (c.716G>A, p.Arg239Gln) in the C-terminus of the gap junction protein alpha-1 (GJA1) coding for connexin 43 (Cx43). We confirmed this mutation in 6 individuals from 3 additional families. The homozygous mutation cosegregated only with affected family members. Connexin 43 is a major component of gap junctions in osteoblasts, osteocytes, osteoclasts and chondrocytes. Gap junctions are responsible for the diffusion of low molecular weight molecules between cells. Mutations in Cx43 cause several dominant and recessive disorders involving developmental abnormalities of bone such as dominant and recessive oculodentodigital dysplasia (ODDD; MIM #164200, 257850) and isolated syndactyly type III (MIM #186100), the characteristic digital anomaly in ODDD. However, characteristic ocular and dental features of ODDD as well as syndactyly are absent in patients with the recessive Arg239Gln Cx43 mutation. Bone remodeling mechanisms disrupted by this novel Cx43 mutation remain to be elucidated. PMID:23951358

  10. Rosai-Dorfman Disease Harboring an Activating KRAS K117N Missense Mutation.

    PubMed

    Shanmugam, Vignesh; Margolskee, Elizabeth; Kluk, Michael; Giorgadze, Tamara; Orazi, Attilio

    2016-09-01

    Rosai-Dorfman disease (RDD) or sinus histiocytosis with massive lymphadenopathy is a rare histiocytic proliferation that is generally considered to be reactive with a benign clinical course. The etiology of RDD is very poorly understood. Recent studies have shown frequent BRAF, NRAS, KRAS, and PIK3CA activating mutations in several histiocytic neoplasms highlighting the emerging importance of the RAF/MEK/ERK pathway in the pathogenesis of these diseases. Here we report a case of Rosai-Dorfman disease involving the submandibular salivary gland with a KRAS K117N missense mutation discovered by next-generation sequencing. These results suggest that at least a subset of RDD cases may be clonal processes. Further mutational studies on this rare histiocytic disease should be undertaken to better characterize its pathogenesis as well as open up potential avenues for therapy. PMID:26922062

  11. Molecular and functional consequences of Smad4 C-terminal missense mutations in colorectal tumour cells.

    PubMed Central

    De Bosscher, Karolien; Hill, Caroline S; Nicolás, Francisco J

    2004-01-01

    Smad4 is an essential signal transducer of the transforming growth factor beta (TGF-beta) signalling pathway and has been identified as a tumour suppressor, being mutated in approx. 50% of pancreatic cancers and approx. 15% of colorectal cancers. Two missense mutations in the C-terminal domain of Smad4, D351H (Asp351-->His) and D537Y (Asp537-->Tyr), have been described recently in the human colorectal cancer cell lines CACO-2 and SW948 respectively [Woodford-Richens, Rowan, Gorman, Halford, Bicknell, Wasan, Roylance, Bodmer and Tomlinson (2001) Proc. Natl. Acad. Sci. U.S.A. 98, 9719-9723]. Previous work in vitro suggested that only Asp-351 was required for interaction with Smad2 [Wu, Fairman, Penry and Shi (2001) J. Biol. Chem. 276, 20688-20694]. In the present study, we investigate the functional consequences of these point mutations in vivo. We demonstrate that neither of these colorectal cancer cells undergo growth arrest in response to TGF-beta, which can be explained, at least in part, by their inability to up-regulate cyclin-dependent kinase inhibitors p21 (CIP1 ) or p15 ( INK4b) after TGF-beta stimulation. Although the point-mutated Smad4s are expressed at normal levels in these colorectal cancer cells, they cannot interact with either TGF-beta-induced phosphorylated Smad2 or Smad3. As a result, these Smad4 mutants do not accumulate in the nucleus after TGF-beta stimulation, are not recruited to DNA by relevant Smad-binding transcription factors and cannot generate transcriptionally active DNA-bound complexes. Therefore both these colorectal tumour cells completely lack functional Smad4 activity owing to the missense mutations. Given the location of these mutations in the three-dimensional structure of the Smad4 C-terminal domain, the results also give us significant insights into Smad complex formation. PMID:14715079

  12. A novel AMH missense mutation in a patient with persistent Müllerian duct syndrome.

    PubMed

    van der Zwan, Y G; Brüggenwirth, H T; Drop, S L S; Wolffenbuttel, K P; Madern, G C; Looijenga, L H J; Visser, J A

    2012-01-01

    Persistent Müllerian duct syndrome (PMDS) is characterized by the presence of a uterus, fallopian tubes, and the upper part of the vagina in phenotypic normal male patients. Here, we report a patient diagnosed with PMDS with a novel homozygous missense mutation in the anti-Müllerian hormone (AMH) gene (single nucleotide insertion (C) at position 208 (c.208dup, p.Leu70fs)) leading to a frameshift and the introduction of a premature stop codon. Biopsy of both gonads revealed that germ cells were present in an irregular distribution. However, the absence of OCT3/4, PLAP and c-KIT expression indicated physiological maturation. PMID:22797409

  13. Missense mutations in the growth hormone receptor dimerization region in Laron syndrome

    SciTech Connect

    Berg, M.A.; Francke, U. |; Geffner, M.E.; Bersch, N.

    1994-09-01

    Laron syndrome (LS) is an autosomal recessively inherited condition characterized by insensitivity to endogenous and exogenous GH. Affected individuals have severe episodes and other characteristic features. GH receptor gene mutations are present in all affected individuals in whom molecular studies have been reported. The GH receptor is a plasma membrane-spanning protein in which the extracellular domain binds circulating GH and the intracellular domain interacts with the JAK-2 kinase and possibly other intracellular signaling molecules. GH receptor dimerization occurs on GH binding and is thought to be required for normal signal transduction. We have studied the GH receptor genes of four unrelated individuals affected with LS from the United States, Italy, Saudi Arabia, and India. We have identified four different missense mutations that alter consecutive amino acids 152 to 155 in or near the dimerization domain of the GH receptor. One of these mutations, D152H, has been reported previously in Asian LS patients and, in in vitro studies, the mutant receptor was unable to dimerize. This report increases to over 20 the number of different GH receptor gene mutations that have been reported in LS patients and defines the first apparent mutational {open_quotes}hotspot{close_quotes} region in this gene. This cluster of mutations in patients with classic LS phenotype provides additional in vivo evidence that receptor dimerization plays an important role in signaling GH`s growth promoting and metabolic effects. Further in vitro studies of the mutations in this region are in progress.

  14. In silico prediction of tumor antigens derived from functional missense mutations of the cancer gene census

    PubMed Central

    Khalili, Jahan S.; Hanson, Russell W.; Szallasi, Zoltan

    2012-01-01

    Antigen-specific immune responses against peptides derived from missense gene mutations have been identified in multiple cancers. The application of personalized peptide vaccines based on the tumor mutation repertoire of each cancer patient is a near-term clinical reality. These peptides can be identified for pre-validation by leveraging the results of massive gene sequencing efforts in cancer. In this study, we utilized NetMHC 3.2 to predict nanomolar peptide binding affinity to 57 human HLA-A and B alleles. All peptides were derived from 5,685 missense mutations in 312 genes annotated as functionally relevant in the Cancer Genome Project. Of the 26,672,189 potential 8–11 mer peptide-HLA pairs evaluated, 0.4% (127,800) display binding affinities < 50 nM, predicting high affinity interactions. These peptides can be segregated into two groups based on the binding affinity to HLA proteins relative to germline-encoded sequences: peptides for which both the mutant and wild-type forms are high affinity binders, and peptides for which only the mutant form is a high affinity binder. Current evidence directs the attention to mutations that increase HLA binding affinity, as compared with cognate wild-type peptide sequences, as these potentially are more relevant for vaccine development from a clinical perspective. Our analysis generated a database including all predicted HLA binding peptides and the corresponding change in binding affinity as a result of point mutations. Our study constitutes a broad foundation for the development of personalized peptide vaccines that hone-in on functionally relevant targets in multiple cancers in individuals with diverse HLA haplotypes. PMID:23243591

  15. Genetic and structure-function studies of missense mutations in human endothelial lipase.

    PubMed

    Razzaghi, Hamid; Tempczyk-Russell, Anna; Haubold, Kurt; Santorico, Stephanie A; Shokati, Touraj; Christians, Uwe; Churchill, Mair E A

    2013-01-01

    Endothelial lipase (EL) plays a pivotal role in HDL metabolism. We sought to characterize EL and its interaction with HDL as well as its natural variants genetically, functionally and structurally. We screened our biethnic population sample (n = 802) for selected missense mutations (n = 5) and identified T111I as the only common variant. Multiple linear regression analyses in Hispanic subjects revealed an unexpected association between T111I and elevated LDL-C (p-value = 0.012) and total cholesterol (p-value = 0.004). We examined lipase activity of selected missense mutants (n = 10) and found different impacts on EL function, ranging from normal to complete loss of activity. EL-HDL lipidomic analyses indicated that EL has a defined remodeling of HDL without exhaustion of the substrate and a distinct and preference for several fatty acids that are lipid mediators and known for their potent pro- and anti-inflammatory properties. Structural studies using homology modeling revealed a novel α/β motif in the C-domain, unique to EL. The EL dimer was found to have the flexibility to expand and to bind various sizes of HDL particles. The likely impact of the all known missense mutations (n = 18) on the structure of EL was examined using molecular modeling and the impact they may have on EL lipase activity using a novel structure-function slope based on their structural free energy differences. The results of this multidisciplinary approach delineated the impact of EL and its variants on HDL. Moreover, the results suggested EL to have the capacity to modulate vascular health through its role in fatty acid-based signaling pathways. PMID:23536757

  16. Bioinformatic Analysis of Pathogenic Missense Mutations of Activin Receptor Like Kinase 1 Ectodomain

    PubMed Central

    Scotti, Claudia; Olivieri, Carla; Boeri, Laura; Canzonieri, Cecilia; Ornati, Federica; Buscarini, Elisabetta; Pagella, Fabio; Danesino, Cesare

    2011-01-01

    Activin A receptor, type II-like kinase 1 (also called ALK1), is a serine-threonine kinase predominantly expressed on endothelial cells surface. Mutations in its ACVRL1 encoding gene (12q11-14) cause type 2 Hereditary Haemorrhagic Telangiectasia (HHT2), an autosomal dominant multisystem vascular dysplasia. The study of the structural effects of mutations is crucial to understand their pathogenic mechanism. However, while an X-ray structure of ALK1 intracellular domain has recently become available (PDB ID: 3MY0), structure determination of ALK1 ectodomain (ALK1EC) has been elusive so far. We here describe the building of a homology model for ALK1EC, followed by an extensive bioinformatic analysis, based on a set of 38 methods, of the effect of missense mutations at the sequence and structural level. ALK1EC potential interaction mode with its ligand BMP9 was then predicted combining modelling and docking data. The calculated model of the ALK1EC allowed mapping and a preliminary characterization of HHT2 associated mutations. Major structural changes and loss of stability of the protein were predicted for several mutations, while others were found to interfere mainly with binding to BMP9 or other interactors, like Endoglin (CD105), whose encoding ENG gene (9q34) mutations are known to cause type 1 HHT. This study gives a preliminary insight into the potential structure of ALK1EC and into the structural effects of HHT2 associated mutations, which can be useful to predict the potential effect of each single mutation, to devise new biological experiments and to interpret the biological significance of new mutations, private mutations, or non-synonymous polymorphisms. PMID:22028876

  17. The Opdc missense mutation of Pax2 has a milder than loss-of-function phenotype

    PubMed Central

    Cross, Sally H.; McKie, Lisa; West, Katrine; Coghill, Emma L.; Favor, Jack; Bhattacharya, Shoumo; Brown, Steve D.M.; Jackson, Ian J.

    2011-01-01

    Renal-coloboma syndrome, also known as papillorenal syndrome, is an autosomal dominant human disorder in which optic disc coloboma is associated with kidney abnormalities. Mutations in the paired domain transcription factor PAX2 have been found to be the underlying cause of this disease. Disease severity varies between patients, and in some cases, renal hypoplasia has been found in the absence of any retinal defects. Here we report an N-ethyl-N-nitrosourea-induced mouse mutation, Opdc, which is an isoleucinetothreonine missense mutation, I40T, in the first α-helix of the Pax2 paired domain. The mutant protein binds target DNA sequences less strongly than the wild-type protein and acts poorly to transactivate target promoters in culture. The phenotypic consequence of this mutation on the development of the eye and ear is similar to that reported for null alleles of Pax2. However, in homozygotes, cerebellar development is normal on a genetic background in which loss of Pax2 results in failure of cerebellar formation. Moreover, there is a genetic background effect on the heterozygous phenotype such that on some strain backgrounds, kidney development is unaffected. Opdc is the first hypomorphic mutation reported for Pax2 that differs in phenotype from loss-of-function mutations. These results suggest that PAX2 is a strong candidate gene for cases in which human patients have optic disc coloboma not associated with renal dysplasia. PMID:20943750

  18. Effect of BET Missense Mutations on Bromodomain Function, Inhibitor Binding and Stability

    PubMed Central

    Lori, Laura; Pasquo, Alessandra; Lori, Clorinda; Petrosino, Maria; Chiaraluce, Roberta; Tallant, Cynthia; Knapp, Stefan; Consalvi, Valerio

    2016-01-01

    Lysine acetylation is an important epigenetic mark regulating gene transcription and chromatin structure. Acetylated lysine residues are specifically recognized by bromodomains, small protein interaction modules that read these modification in a sequence and acetylation dependent way regulating the recruitment of transcriptional regulators and chromatin remodelling enzymes to acetylated sites in chromatin. Recent studies revealed that bromodomains are highly druggable protein interaction domains resulting in the development of a large number of bromodomain inhibitors. BET bromodomain inhibitors received a lot of attention in the oncology field resulting in the rapid translation of early BET bromodomain inhibitors into clinical studies. Here we investigated the effects of mutations present as polymorphism or found in cancer on BET bromodomain function and stability and the influence of these mutants on inhibitor binding. We found that most BET missense mutations localize to peripheral residues in the two terminal helices. Crystal structures showed that the three dimensional structure is not compromised by these mutations but mutations located in close proximity to the acetyl-lysine binding site modulate acetyl-lysine and inhibitor binding. Most mutations affect significantly protein stability and tertiary structure in solution, suggesting new interactions and an alternative network of protein-protein interconnection as a consequence of single amino acid substitution. To our knowledge this is the first report studying the effect of mutations on bromodomain function and inhibitor binding. PMID:27403962

  19. Truncating and missense mutations in IGHMBP2 cause Charcot-Marie Tooth disease type 2.

    PubMed

    Cottenie, Ellen; Kochanski, Andrzej; Jordanova, Albena; Bansagi, Boglarka; Zimon, Magdalena; Horga, Alejandro; Jaunmuktane, Zane; Saveri, Paola; Rasic, Vedrana Milic; Baets, Jonathan; Bartsakoulia, Marina; Ploski, Rafal; Teterycz, Pawel; Nikolic, Milos; Quinlivan, Ros; Laura, Matilde; Sweeney, Mary G; Taroni, Franco; Lunn, Michael P; Moroni, Isabella; Gonzalez, Michael; Hanna, Michael G; Bettencourt, Conceicao; Chabrol, Elodie; Franke, Andre; von Au, Katja; Schilhabel, Markus; Kabzińska, Dagmara; Hausmanowa-Petrusewicz, Irena; Brandner, Sebastian; Lim, Siew Choo; Song, Haiwei; Choi, Byung-Ok; Horvath, Rita; Chung, Ki-Wha; Zuchner, Stephan; Pareyson, Davide; Harms, Matthew; Reilly, Mary M; Houlden, Henry

    2014-11-01

    Using a combination of exome sequencing and linkage analysis, we investigated an English family with two affected siblings in their 40s with recessive Charcot-Marie Tooth disease type 2 (CMT2). Compound heterozygous mutations in the immunoglobulin-helicase-μ-binding protein 2 (IGHMBP2) gene were identified. Further sequencing revealed a total of 11 CMT2 families with recessively inherited IGHMBP2 gene mutations. IGHMBP2 mutations usually lead to spinal muscular atrophy with respiratory distress type 1 (SMARD1), where most infants die before 1 year of age. The individuals with CMT2 described here, have slowly progressive weakness, wasting and sensory loss, with an axonal neuropathy typical of CMT2, but no significant respiratory compromise. Segregating IGHMBP2 mutations in CMT2 were mainly loss-of-function nonsense in the 5' region of the gene in combination with a truncating frameshift, missense, or homozygous frameshift mutations in the last exon. Mutations in CMT2 were predicted to be less aggressive as compared to those in SMARD1, and fibroblast and lymphoblast studies indicate that the IGHMBP2 protein levels are significantly higher in CMT2 than SMARD1, but lower than controls, suggesting that the clinical phenotype differences are related to the IGHMBP2 protein levels. PMID:25439726

  20. A Novel Functional Missense Mutation p.T219A in Type 1 Gaucher's Disease

    PubMed Central

    Liu, Lin-Yu; Liu, Fei; Du, Si-Chen; Jiang, Sha-Yi; Wang, Hui-Jun; Zhang, Jin; Wang, Wei; Ma, Duan

    2016-01-01

    Background: Gaucher's disease (GD) is an autosomal recessive disorder caused by a deficiency of acid β-glucosidase (glucocerebrosidase [GBA]) that results in the accumulation of glucocerebroside within macrophages. Many mutations have been reported to be associated with this disorder. This study aimed to discover more mutations and provide data for the genetic pattern of the gene, which will help the development of quick and accurate genetic diagnostic tools for this disease. Methods: Genomic DNA was obtained from peripheral blood leukocytes of the patient and Sanger sequencing is used to sequence GBA gene. Sequence alignments of mammalian β-GBA (GCase) and three-dimensional protein structure prediction of the mutation were made. A construct of this mutant and its compound heterozygous counterpart were used to measure GCase in vitro. Results: GCase is relatively conserved at p.T219A. This novel mutation differs from its wild-type in structure. Moreover, it also causes a reduction in GCase enzyme activity. Conclusion: This novel mutation (c.655A>G, p.T219A) is a pathogenic missense mutation, which contributes to GD. PMID:27098793

  1. A missense mutation in the beta-2 integrin gene (ITGB2) causes canine leukocyte adhesion deficiency.

    PubMed

    Kijas, J M; Bauer, T R; Gäfvert, S; Marklund, S; Trowald-Wigh, G; Johannisson, A; Hedhammar, A; Binns, M; Juneja, R K; Hickstein, D D; Andersson, L

    1999-10-01

    Canine leukocyte adhesion deficiency (CLAD) is a fatal immunodeficiency disease found in Irish setters. The clinical manifestations of CLAD are very similar to LAD in humans and BLAD in cattle, which are both caused by mutations in ITGB2 encoding the leukocyte integrin beta-2 subunit (CD18). Sequence analysis of the ITGB2 coding sequence from a CLAD dog and a healthy control revealed a single missense mutation, Cys36Ser. This cysteine residue is conserved among all beta integrins, and the mutation most likely disrupts a disulfide bond. The mutation showed a complete association with CLAD in Irish setters and was not found in a sample of dogs from other breeds. The causative nature of this mutation was confirmed by transduction experiments using retroviral vectors and human LAD EBV B-cells. The normal canine CD18 formed heterodimers with the human CD11 subunit, whereas gene transfer of the mutant CD18 resulted in very low levels of CD11/CD18 expression. The identification of the causative mutation for CLAD now makes it possible to identify carrier animals with a simple diagnostic DNA test, and it forms the basis for using CLAD as a large animal model for the development and evaluation of clinical treatments for human LAD. PMID:10512685

  2. Effect of BET Missense Mutations on Bromodomain Function, Inhibitor Binding and Stability.

    PubMed

    Lori, Laura; Pasquo, Alessandra; Lori, Clorinda; Petrosino, Maria; Chiaraluce, Roberta; Tallant, Cynthia; Knapp, Stefan; Consalvi, Valerio

    2016-01-01

    Lysine acetylation is an important epigenetic mark regulating gene transcription and chromatin structure. Acetylated lysine residues are specifically recognized by bromodomains, small protein interaction modules that read these modification in a sequence and acetylation dependent way regulating the recruitment of transcriptional regulators and chromatin remodelling enzymes to acetylated sites in chromatin. Recent studies revealed that bromodomains are highly druggable protein interaction domains resulting in the development of a large number of bromodomain inhibitors. BET bromodomain inhibitors received a lot of attention in the oncology field resulting in the rapid translation of early BET bromodomain inhibitors into clinical studies. Here we investigated the effects of mutations present as polymorphism or found in cancer on BET bromodomain function and stability and the influence of these mutants on inhibitor binding. We found that most BET missense mutations localize to peripheral residues in the two terminal helices. Crystal structures showed that the three dimensional structure is not compromised by these mutations but mutations located in close proximity to the acetyl-lysine binding site modulate acetyl-lysine and inhibitor binding. Most mutations affect significantly protein stability and tertiary structure in solution, suggesting new interactions and an alternative network of protein-protein interconnection as a consequence of single amino acid substitution. To our knowledge this is the first report studying the effect of mutations on bromodomain function and inhibitor binding. PMID:27403962

  3. Rational Manual and Automated Scoring Thresholds for the Immunohistochemical Detection of TP53 Missense Mutations in Human Breast Carcinomas.

    PubMed

    Taylor, Nicholas J; Nikolaishvili-Feinberg, Nana; Midkiff, Bentley R; Conway, Kathleen; Millikan, Robert C; Geradts, Joseph

    2016-07-01

    Missense mutations in TP53 are common in human breast cancer, have been associated with worse prognosis, and may predict therapy effect. TP53 missense mutations are associated with aberrant accumulation of p53 protein in tumor cell nuclei. Previous studies have used relatively arbitrary cutoffs to characterize breast tumors as positive for p53 staining by immunohistochemical assays. This study aimed to objectively determine optimal thresholds for p53 positivity by manual and automated scoring methods using whole tissue sections from the Carolina Breast Cancer Study. p53-immunostained slides were available for 564 breast tumors previously assayed for TP53 mutations. Average nuclear p53 staining intensity was manually scored as negative, borderline, weak, moderate, or strong and percentage of positive tumor cells was estimated. Automated p53 signal intensity was measured using the Aperio nuclear v9 algorithm combined with the Genie histology pattern recognition tool and tuned to achieve optimal nuclear segmentation. Receiver operating characteristic curve analysis was performed to determine optimal cutoffs for average staining intensity and percent cells positive to distinguish between tumors with and without a missense mutation. Receiver operating characteristic curve analysis demonstrated a threshold of moderate average nuclear staining intensity as a good surrogate for TP53 missense mutations in both manual (area under the curve=0.87) and automated (area under the curve=0.84) scoring systems. Both manual and automated immunohistochemical scoring methods predicted missense mutations in breast carcinomas with high accuracy. Validation of the automated intensity scoring threshold suggests a role for such algorithms in detecting TP53 missense mutations in high throughput studies. PMID:26200835

  4. Prefoldin Promotes Proteasomal Degradation of Cytosolic Proteins with Missense Mutations by Maintaining Substrate Solubility

    PubMed Central

    Young, Barry P.; Loewen, Christopher J.; Mayor, Thibault

    2016-01-01

    Misfolded proteins challenge the ability of cells to maintain protein homeostasis and can accumulate into toxic protein aggregates. As a consequence, cells have adopted a number of protein quality control pathways to prevent protein aggregation, promote protein folding, and target terminally misfolded proteins for degradation. In this study, we employed a thermosensitive allele of the yeast Guk1 guanylate kinase as a model misfolded protein to investigate degradative protein quality control pathways. We performed a flow cytometry based screen to identify factors that promote proteasomal degradation of proteins misfolded as the result of missense mutations. In addition to the E3 ubiquitin ligase Ubr1, we identified the prefoldin chaperone subunit Gim3 as an important quality control factor. Whereas the absence of GIM3 did not impair proteasomal function or the ubiquitination of the model substrate, it led to the accumulation of the poorly soluble model substrate in cellular inclusions that was accompanied by delayed degradation. We found that Gim3 interacted with the Guk1 mutant allele and propose that prefoldin promotes the degradation of the unstable model substrate by maintaining the solubility of the misfolded protein. We also demonstrated that in addition to the Guk1 mutant, prefoldin can stabilize other misfolded cytosolic proteins containing missense mutations. PMID:27448207

  5. Prefoldin Promotes Proteasomal Degradation of Cytosolic Proteins with Missense Mutations by Maintaining Substrate Solubility.

    PubMed

    Comyn, Sophie A; Young, Barry P; Loewen, Christopher J; Mayor, Thibault

    2016-07-01

    Misfolded proteins challenge the ability of cells to maintain protein homeostasis and can accumulate into toxic protein aggregates. As a consequence, cells have adopted a number of protein quality control pathways to prevent protein aggregation, promote protein folding, and target terminally misfolded proteins for degradation. In this study, we employed a thermosensitive allele of the yeast Guk1 guanylate kinase as a model misfolded protein to investigate degradative protein quality control pathways. We performed a flow cytometry based screen to identify factors that promote proteasomal degradation of proteins misfolded as the result of missense mutations. In addition to the E3 ubiquitin ligase Ubr1, we identified the prefoldin chaperone subunit Gim3 as an important quality control factor. Whereas the absence of GIM3 did not impair proteasomal function or the ubiquitination of the model substrate, it led to the accumulation of the poorly soluble model substrate in cellular inclusions that was accompanied by delayed degradation. We found that Gim3 interacted with the Guk1 mutant allele and propose that prefoldin promotes the degradation of the unstable model substrate by maintaining the solubility of the misfolded protein. We also demonstrated that in addition to the Guk1 mutant, prefoldin can stabilize other misfolded cytosolic proteins containing missense mutations. PMID:27448207

  6. A novel COL11A1 missense mutation in siblings with non-ocular Stickler syndrome

    PubMed Central

    Kohmoto, Tomohiro; Tsuji, Atsumi; Morita, Kei-ichi; Naruto, Takuya; Masuda, Kiyoshi; Kashimada, Kenichi; Enomoto, Keisuke; Morio, Tomohiro; Harada, Hiroyuki; Imoto, Issei

    2016-01-01

    Stickler syndrome (STL) is an autosomal, dominantly inherited, clinically variable and genetically heterogeneous connective tissue disorder characterized by ocular, auditory, orofacial and skeletal abnormalities. We conducted targeted resequencing using a next-generation sequencer for molecular diagnosis of a 2-year-old girl who was clinically suspected of having STL with Pierre Robin sequence. We detected a novel heterozygous missense mutation, NM_001854.3:n.4838G>A [NM_001854.3 (COL11A1_v001):c.4520G>A], in COL11A1, resulting in a Gly to Asp substitution at position 1507 [NM_001854.3(COL11A1_i001)] within one of the collagen-like domains of the triple helical region. The same mutation was detected in her 4-year-old brother with cleft palate and high-frequency sensorineural hearing loss. PMID:27081569

  7. Detection of a Novel Missense Mutations in Atrichia with Papular Lesions

    PubMed Central

    Kim, Sang-Hyun; Chun, Ji-Sung; Joo, Myeong-Hoon; Kim, Ji-Yeon; Hwang, Seon-Wook; Kang, Hyo-Joon; Park, Sung-Wook; Sung, Ho-Suk

    2011-01-01

    Background Atrichia with papular lesions (APL) is a rare inherited disease characterized by early onset of total hair loss, followed by papular lesions over the extensor areas of the body. Recently, mutations in the human hairless (HR) gene have been implicated in its pathogenesis. The identification of mutations in the HR gene is important for differentiating between APL and alopecia universalis (AU). Objective We compared the HR genes of patients with presumed AU who showed minimal or no response to treatment with the HR genes of healthy controls. Methods The subjects were 11 patients with presumed AU who had not responded to treatments. Fifty healthy people were included as controls for molecular analysis. To screen for mutations, polymerase chain reaction was performed. Results DNA analysis identified a novel heterozygous G-to-A transition at nucleotide position 191 in exon 5. The mutation was not found in the controls, other AU patients, or any unaffected family members except for the patients' mother and maternal grandfather, who were heterozygous HR gene carriers. Conclusion Our study identifies a novel missense mutation in exon 5 of the HR gene in a Korean APL patient previously diagnosed as AU. PMID:21747609

  8. TULP1 Missense Mutations Induces the Endoplasmic Reticulum Unfolded Protein Response Stress Complex (ER-UPR).

    PubMed

    Lobo, Glenn P; Ebke, Lindsey A; Au, Adrian; Hagstrom, Stephanie A

    2016-01-01

    Mutations in the TULP1 gene are associated with early-onset retinitis pigmentosa (RP); however, the molecular mechanisms related to the deleterious effects of TULP1 mutations remains unknown. Several studies have shown that misfolded proteins secondary to genetic mutations can accumulate within the endoplasmic reticulum (ER), causing activation of the unfolded protein response (UPR) complex followed by cellular apoptosis. We hypothesize that TULP1 mutations produce misfolded protein products that accumulate in the ER and induce cellular apoptosis via the UPR. To test our hypothesis, we first performed three in-silico analyses of TULP1 missense mutations (I459K, R420P and F491L), which predicted misfolded protein products. Subsequently, the three mutant TULP1-GFP constructs and wild-type (wt) TULP1-GFP were transiently transfected into hTERT-RPE-1 cells. Staining of cells using ER tracker followed by confocal microscopy showed wt-TULP1 localized predominantly to the cytoplasm and plasma membrane. In contrast, all three mutant TULP1 proteins revealed cytoplasmic punctate staining which co-localized with the ER. Furthermore, western blot analysis of cells expressing mutant TULP1 proteins revealed induction of downstream targets of the ER-UPR complex, including BiP/GPR-78, phosphorylated-PERK (Thr980) and CHOP. Our in-vitro analyses suggest that mutant TULP1 proteins are misfolded and accumulate within the ER leading to induction of the UPR stress response complex. PMID:26427415

  9. A Missense Mutation in HK1 Leads to Autosomal Dominant Retinitis Pigmentosa

    PubMed Central

    Wang, Feng; Wang, Yandong; Zhang, Bin; Zhao, Li; Lyubasyuk, Vera; Wang, Keqing; Xu, Mingchu; Li, Yumei; Wu, Frances; Wen, Cindy; Bernstein, Paul S.; Lin, Danni; Zhu, Susanna; Wang, Hui; Zhang, Kang; Chen, Rui

    2014-01-01

    Purpose. Retinitis pigmentosa (RP) is a genetically heterogeneous disease with over 60 causative genes known to date. Nevertheless, approximately 40% of RP cases remain genetically unsolved, suggesting that many novel disease-causing genes are yet to be identified. In this study, we aimed to identify the causative mutation for a large autosomal dominant RP (adRP) family with negative results from known retinal disease gene screening. Methods. Linkage analysis followed by whole-exome sequencing was performed. Stringent variant filtering and prioritization was carried out to identify the causative mutation. Results. Linkage analysis identified a minimal disease region of 8 Mb on chromosome 10 with a peak parametric logarithm (base 10) of odds (LOD) score of 3.500. Further whole-exome sequencing identified a heterozygous missense mutation (NM_000188.2:c.2539G>A, p.E847K) in hexokinase 1 (HK1) that segregated with the disease phenotype in the family. Biochemical assays showed that the E847K mutation does not affect hexokinase enzymatic activity or the protein stability, suggesting that the mutation may impact other uncharacterized function or result in a gain of function of HK1. Conclusions. Here, we identified HK1 as a novel causative gene for adRP. This is the first report that associates the glucose metabolic pathway with human retinal degenerative disease, suggesting a potential new disease mechanism. PMID:25316723

  10. Missense variations in the cystic fibrosis gene: Heteroduplex formation in the F508C mutation

    SciTech Connect

    Macek, M. Jr.; Ladanyi, L.; Buerger, J.; Reis, A. )

    1992-11-01

    Kobayashi et al. (1990) have described missense variations in the conserved region of exon 10 of the cystic fibrosis (CF) transmembrane conductance regulator gene. In their paper, two [Delta]F508/F508C compound heterozygous individuals were reported. Clinical and epithelial physiological studies in both cases were normal, suggesting that the substitution of cysteine for phenylalanine at position 508, the F508C mutation, is benign. However, Kerem et al. reported a patient with this substitution who had typical symptoms of CF. In routine [Delta]F508 mutation screening by visualization of the 3-bp deletion on a 12% polyacrylamide gel the authors detected an abnormal heteroduplex in the father of a CF patient of German origin. Subsequent direct sequencing of the PCR product confirmed that this clinically normal father is a compound heterozygote for the [Delta]F508/F508C mutations. This heteroduplex is slightly different from the usual heteroduplex in [Delta]F508/F508C heteroduplex was not published, it is likely that similar cases can be overseen during the widely performed [Delta]F508 mutation screening by PAGE. Detection of more cases, such as the one presented here, together with careful, standardized clinical examination of the proband, would be valuable to verify the nature of this mutation. 4 refs., 1 fig.

  11. PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity.

    PubMed

    Monnier, Carine; Dodé, Catherine; Fabre, Ludovic; Teixeira, Luis; Labesse, Gilles; Pin, Jean-Philippe; Hardelin, Jean-Pierre; Rondard, Philippe

    2009-01-01

    Kallmann syndrome (KS) combines hypogonadism due to gonadotropin-releasing hormone deficiency, and anosmia or hyposmia, related to defective olfactory bulb morphogenesis. In a large series of KS patients, ten different missense mutations (p.R85C, p.R85H, p.R164Q, p.L173R, p.W178S, p.Q210R, p.R268C, p.P290S, p.M323I, p.V331M) have been identified in the gene encoding the G protein-coupled receptor prokineticin receptor-2 (PROKR2), most often in the heterozygous state. Many of these mutations were, however, also found in clinically unaffected individuals, thus raising the question of their actual implication in the KS phenotype. We reproduced each of the ten mutations in a recombinant murine Prokr2, and tested their effects on the signalling activity in transfected HEK-293 cells, by measuring intracellular calcium release upon ligand-activation of the receptor. We found that all mutated receptors except one (M323I) had decreased signalling activities. These could be explained by different defective mechanisms. Three mutations (L173R, W178S, P290S) impaired cell surface-targeting of the receptor. One mutation (Q210R) abolished ligand-binding. Finally, five mutations (R85C, R85H, R164Q, R268C, V331M) presumably impaired G protein-coupling of the receptor. In addition, when wild-type and mutant receptors were coexpressed in HEK-293 cells, none of the mutant receptors that were retained within the cells did affect cell surface-targeting of the wild-type receptor, and none of the mutant receptors properly addressed at the plasma membrane did affect wild-type receptor signalling activity. This argues against a dominant negative effect of the mutations in vivo. PMID:18826963

  12. PROKR2 missense mutations associated with Kallmann syndrome impair receptor signalling activity

    PubMed Central

    Monnier, Carine; Dodé, Catherine; Fabre, Ludovic; Teixeira, Luis; Labesse, Gilles; Pin, Jean-Philippe; Hardelin, Jean-Pierre; Rondard, Philippe

    2009-01-01

    Kallmann syndrome (KS) combines hypogonadism due to gonadotropin-releasing hormone deficiency, and anosmia or hyposmia, related to defective olfactory bulb morphogenesis. In a large series of KS patients, ten different missense mutations (p.R85C, p.R85H, p.R164Q, p.L173R, p.W178S, p.Q210R, p.R268C, p.P290S, p.M323I, p.V331M) have been identified in the gene encoding the G protein-coupled receptor prokineticin receptor-2 (PROKR2), most often in the heterozygous state. Many of these mutations were, however, also found in clinically unaffected individuals, thus raising the question of their actual implication in the KS phenotype. We reproduced each of the ten mutations in a recombinant murine Prokr2, and tested their effects on the signalling activity in transfected HEK-293 cells, by measuring intracellular calcium release upon ligand-activation of the receptor. We found that all mutated receptors except one (M323I) had decreased signalling activities. These could be explained by different defective mechanisms. Three mutations (L173R, W178S, P290S) impaired cell surface-targeting of the receptor. One mutation (Q210R) abolished ligand-binding. Finally, five mutations (R85C, R85H, R164Q, R268C, V331M) presumably impaired G protein-coupling of the receptor. In addition, when wild-type and mutant receptors were coexpressed in HEK-293 cells, none of the mutant receptors that were retained within the cells did affect cell surface-targeting of the wild-type receptor, and none of the mutant receptors properly addressed at the plasma membrane did affect wild-type receptor signalling activity. This argues against a dominant negative effect of the mutations in vivo. PMID:18826963

  13. Structure-Based Analysis Reveals Cancer Missense Mutations Target Protein Interaction Interfaces

    PubMed Central

    Engin, H. Billur; Kreisberg, Jason F.; Carter, Hannah

    2016-01-01

    Recently it has been shown that cancer mutations selectively target protein-protein interactions. We hypothesized that mutations affecting distinct protein interactions involving established cancer genes could contribute to tumor heterogeneity, and that novel mechanistic insights might be gained into tumorigenesis by investigating protein interactions under positive selection in cancer. To identify protein interactions under positive selection in cancer, we mapped over 1.2 million nonsynonymous somatic cancer mutations onto 4,896 experimentally determined protein structures and analyzed their spatial distribution. In total, 20% of mutations on the surface of known cancer genes perturbed protein-protein interactions (PPIs), and this enrichment for PPI interfaces was observed for both tumor suppressors (Odds Ratio 1.28, P-value < 10−4) and oncogenes (Odds Ratio 1.17, P-value < 10−3). To study this further, we constructed a bipartite network representing structurally resolved PPIs from all available human complexes in the Protein Data Bank (2,864 proteins, 3,072 PPIs). Analysis of frequently mutated cancer genes within this network revealed that tumor-suppressors, but not oncogenes, are significantly enriched with functional mutations in homo-oligomerization regions (Odds Ratio 3.68, P-Value < 10−8). We present two important examples, TP53 and beta-2-microglobulin, for which the patterns of somatic mutations at interfaces provide insights into specifically perturbed biological circuits. In patients with TP53 mutations, patient survival correlated with the specific interactions that were perturbed. Moreover, we investigated mutations at the interface of protein-nucleotide interactions and observed an unexpected number of missense mutations but not silent mutations occurring within DNA and RNA binding sites. Finally, we provide a resource of 3,072 PPI interfaces ranked according to their mutation rates. Analysis of this list highlights 282 novel candidate cancer

  14. Structure-Based Analysis Reveals Cancer Missense Mutations Target Protein Interaction Interfaces.

    PubMed

    Engin, H Billur; Kreisberg, Jason F; Carter, Hannah

    2016-01-01

    Recently it has been shown that cancer mutations selectively target protein-protein interactions. We hypothesized that mutations affecting distinct protein interactions involving established cancer genes could contribute to tumor heterogeneity, and that novel mechanistic insights might be gained into tumorigenesis by investigating protein interactions under positive selection in cancer. To identify protein interactions under positive selection in cancer, we mapped over 1.2 million nonsynonymous somatic cancer mutations onto 4,896 experimentally determined protein structures and analyzed their spatial distribution. In total, 20% of mutations on the surface of known cancer genes perturbed protein-protein interactions (PPIs), and this enrichment for PPI interfaces was observed for both tumor suppressors (Odds Ratio 1.28, P-value < 10-4) and oncogenes (Odds Ratio 1.17, P-value < 10-3). To study this further, we constructed a bipartite network representing structurally resolved PPIs from all available human complexes in the Protein Data Bank (2,864 proteins, 3,072 PPIs). Analysis of frequently mutated cancer genes within this network revealed that tumor-suppressors, but not oncogenes, are significantly enriched with functional mutations in homo-oligomerization regions (Odds Ratio 3.68, P-Value < 10-8). We present two important examples, TP53 and beta-2-microglobulin, for which the patterns of somatic mutations at interfaces provide insights into specifically perturbed biological circuits. In patients with TP53 mutations, patient survival correlated with the specific interactions that were perturbed. Moreover, we investigated mutations at the interface of protein-nucleotide interactions and observed an unexpected number of missense mutations but not silent mutations occurring within DNA and RNA binding sites. Finally, we provide a resource of 3,072 PPI interfaces ranked according to their mutation rates. Analysis of this list highlights 282 novel candidate cancer genes

  15. Functional Impact of 14 Single Nucleotide Polymorphisms Causing Missense Mutations of Human α7 Nicotinic Receptor

    PubMed Central

    Zhang, Qinhui; Du, Yingjie; Zhang, Jianliang; Xu, Xiaojun; Xue, Fenqin; Guo, Cong; Huang, Yao; Lukas, Ronald J.; Chang, Yongchang

    2015-01-01

    The α7nicotinic receptor (nAChR) is a major subtype of the nAChRs in the central nervous system, and the receptor plays an important role in brain function. In the dbSNP database, there are 55 single nucleotide polymorphisms (SNPs) that cause missense mutations of the human α7nAChR in the coding region. In this study, we tested the impact of 14 SNPs that cause missense mutations in the agonist binding site or the coupling region between binding site and channel gate on the receptor function. The wild type or mutant receptors were expressed or co-expressed in Xenopus oocytes, and the agonist-induced currents were tested using two-electrode voltage clamp. Our results demonstrated that 6 mutants were nonfunctional, 4 mutants had reduced current expression, and 1 mutants altered ACh and nicotine efficacy in the opposite direction, and one additional mutant had slightly reduced agonist sensitivity. Interestingly, the function of most of these nonfunctional mutants could be rescued by α7nAChR positive allosteric modulator PNU-120596 and agonist-PAM 4BP-TQS. Finally, when coexpressed with the wild type, the nonfunctional mutants could also influence the receptor function. These changes of the receptor properties by the mutations could potentially have an impact on the physiological function of the α7nAChR-mediated cholinergic synaptic transmission and anti-inflammatory effects in the human SNP carriers. Rescuing the nonfunctional mutants could provide a novel way to treat the related disorders. PMID:26340537

  16. A Missense Mutation in CASK Causes FG Syndrome in an Italian Family

    PubMed Central

    Piluso, Giulio; D'Amico, Francesca; Saccone, Valentina; Bismuto, Ettore; Rotundo, Ida Luisa; Di Domenico, Marina; Aurino, Stefania; Schwartz, Charles E.; Neri, Giovanni; Nigro, Vincenzo

    2009-01-01

    First described in 1974, FG syndrome (FGS) is an X-linked multiple congenital anomaly/mental retardation (MCA/MR) disorder, characterized by high clinical variability and genetic heterogeneity. Five loci (FGS1-5) have so far been linked to this phenotype on the X chromosome, but only one gene, MED12, has been identified to date. Mutations in this gene account for a restricted number of FGS patients with a more distinctive phenotype, referred to as the Opitz-Kaveggia phenotype. We report here that a p.R28L (c.83G→T) missense mutation in CASK causes FGS phenotype in an Italian family previously mapped to Xp11.4-p11.3 (FGS4). The identified missense mutation cosegregates with the phenotype in this family and is absent in 1000 control X chromosomes of the same ethnic origin. An extensive analysis of CASK protein functions as well as structural and dynamic studies performed by molecular dynamics (MD) simulation did not reveal significant alterations induced by the p.R28L substitution. However, we observed a partial skipping of the exon 2 of CASK, presumably a consequence of improper recognition of exonic splicing enhancers (ESEs) induced by the c.83G→T transversion. CASK is a multidomain scaffold protein highly expressed in the central nervous system (CNS) with specific localization to the synapses, where it forms large signaling complexes regulating neurotransmission. We suggest that the observed phenotype is most likely a consequence of an altered CASK expression profile during embryogenesis, brain development, and differentiation. PMID:19200522

  17. Functional Impact of 14 Single Nucleotide Polymorphisms Causing Missense Mutations of Human α7 Nicotinic Receptor.

    PubMed

    Zhang, Qinhui; Du, Yingjie; Zhang, Jianliang; Xu, Xiaojun; Xue, Fenqin; Guo, Cong; Huang, Yao; Lukas, Ronald J; Chang, Yongchang

    2015-01-01

    The α7nicotinic receptor (nAChR) is a major subtype of the nAChRs in the central nervous system, and the receptor plays an important role in brain function. In the dbSNP database, there are 55 single nucleotide polymorphisms (SNPs) that cause missense mutations of the human α7nAChR in the coding region. In this study, we tested the impact of 14 SNPs that cause missense mutations in the agonist binding site or the coupling region between binding site and channel gate on the receptor function. The wild type or mutant receptors were expressed or co-expressed in Xenopus oocytes, and the agonist-induced currents were tested using two-electrode voltage clamp. Our results demonstrated that 6 mutants were nonfunctional, 4 mutants had reduced current expression, and 1 mutants altered ACh and nicotine efficacy in the opposite direction, and one additional mutant had slightly reduced agonist sensitivity. Interestingly, the function of most of these nonfunctional mutants could be rescued by α7nAChR positive allosteric modulator PNU-120596 and agonist-PAM 4BP-TQS. Finally, when coexpressed with the wild type, the nonfunctional mutants could also influence the receptor function. These changes of the receptor properties by the mutations could potentially have an impact on the physiological function of the α7nAChR-mediated cholinergic synaptic transmission and anti-inflammatory effects in the human SNP carriers. Rescuing the nonfunctional mutants could provide a novel way to treat the related disorders. PMID:26340537

  18. Structural and functional analysis of rare missense mutations in human chorionic gonadotrophin β-subunit

    PubMed Central

    Nagirnaja, Liina; Venclovas, Česlovas; Rull, Kristiina; Jonas, Kim C.; Peltoketo, Hellevi; Christiansen, Ole B.; Kairys, Visvaldas; Kivi, Gaily; Steffensen, Rudi; Huhtaniemi, Ilpo T.; Laan, Maris

    2012-01-01

    Heterodimeric hCG is one of the key hormones determining early pregnancy success. We have previously identified rare missense mutations in hCGβ genes with potential pathophysiological importance. The present study assessed the impact of these mutations on the structure and function of hCG by applying a combination of in silico (sequence and structure analysis, molecular dynamics) and in vitro (co-immunoprecipitation, immuno- and bioassays) approaches. The carrier status of each mutation was determined for 1086 North-Europeans [655 patients with recurrent miscarriage (RM)/431 healthy controls from Estonia, Finland and Denmark] using PCR-restriction fragment length polymorphism. The mutation CGB5 p.Val56Leu (rs72556325) was identified in a single heterozygous RM patient and caused a structural hindrance in the formation of the hCGα/β dimer. Although the amount of the mutant hCGβ assembled into secreted intact hCG was only 10% compared with the wild-type, a stronger signaling response was triggered upon binding to its receptor, thus compensating the effect of poor dimerization. The mutation CGB8 p.Pro73Arg (rs72556345) was found in five heterozygotes (three RM cases and two control individuals) and was inherited by two of seven studied live born children. The mutation caused ∼50% of secreted β-subunits to acquire an alternative conformation, but did not affect its biological activity. For the CGB8 p.Arg8Trp (rs72556341) substitution, the applied in vitro methods revealed no alterations in the assembly of intact hCG as also supported by an in silico analysis. In summary, the accumulated data indicate that only mutations with neutral or mild functional consequences might be tolerated in the major hCGβ genes CGB5 and CGB8. PMID:22554618

  19. Structural and functional analysis of rare missense mutations in human chorionic gonadotrophin β-subunit.

    PubMed

    Nagirnaja, Liina; Venclovas, Česlovas; Rull, Kristiina; Jonas, Kim C; Peltoketo, Hellevi; Christiansen, Ole B; Kairys, Visvaldas; Kivi, Gaily; Steffensen, Rudi; Huhtaniemi, Ilpo T; Laan, Maris

    2012-08-01

    Heterodimeric hCG is one of the key hormones determining early pregnancy success. We have previously identified rare missense mutations in hCGβ genes with potential pathophysiological importance. The present study assessed the impact of these mutations on the structure and function of hCG by applying a combination of in silico (sequence and structure analysis, molecular dynamics) and in vitro (co-immunoprecipitation, immuno- and bioassays) approaches. The carrier status of each mutation was determined for 1086 North-Europeans [655 patients with recurrent miscarriage (RM)/431 healthy controls from Estonia, Finland and Denmark] using PCR-restriction fragment length polymorphism. The mutation CGB5 p.Val56Leu (rs72556325) was identified in a single heterozygous RM patient and caused a structural hindrance in the formation of the hCGα/β dimer. Although the amount of the mutant hCGβ assembled into secreted intact hCG was only 10% compared with the wild-type, a stronger signaling response was triggered upon binding to its receptor, thus compensating the effect of poor dimerization. The mutation CGB8 p.Pro73Arg (rs72556345) was found in five heterozygotes (three RM cases and two control individuals) and was inherited by two of seven studied live born children. The mutation caused ~50% of secreted β-subunits to acquire an alternative conformation, but did not affect its biological activity. For the CGB8 p.Arg8Trp (rs72556341) substitution, the applied in vitro methods revealed no alterations in the assembly of intact hCG as also supported by an in silico analysis. In summary, the accumulated data indicate that only mutations with neutral or mild functional consequences might be tolerated in the major hCGβ genes CGB5 and CGB8. PMID:22554618

  20. Compound heterozygosity for nonsense ans missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa.

    PubMed

    McGarth, J A; Christiano, A M; Pulkkinen, L; Eady, R A; Uitto, J

    1996-05-01

    Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of a nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5. PMID:8618058

  1. Compound heterozygosity for nonsense and missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa.

    PubMed

    Christiano, A M; Pulkkinen, L; Eady, R A; Uitto, J

    1996-04-01

    Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DNA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5. PMID:8618020

  2. Biased signaling through G-protein-coupled PROKR2 receptors harboring missense mutations.

    PubMed

    Sbai, Oualid; Monnier, Carine; Dodé, Catherine; Pin, Jean-Philippe; Hardelin, Jean-Pierre; Rondard, Philippe

    2014-08-01

    Various missense mutations in the gene coding for prokineticin receptor 2 (PROKR2), a G-protein-coupled receptor, have been identified in patients with Kallmann syndrome. However, the functional consequences of these mutations on the different signaling pathways of this receptor have not been studied. We first showed that the wild-type PROKR2 can activate different G-protein subtypes (Gq, Gs, and Gi/o) and recruit β-arrestins in transfected HEK-293 cells. We then examined, for each of these signaling pathways, the effects of 9 mutations that did not significantly impair cell surface targeting or ligand binding of the receptor. Four mutant receptors showing defective Gq signaling (R85C, R85H, R164Q, and V331M) could still recruit β-arrestins on ligand activation, which may cause biased signaling in vivo. Conversely, the R80C receptor could activate the 3 types of G proteins but could not recruit β-arrestins. Finally, the R268C receptor could recruit β-arrestins and activate the Gq and Gs signaling pathways but could not activate the Gi/o signaling pathway. Our results validate the concept that mutations in the genes encoding membrane receptors can bias downstream signaling in various ways, possibly leading to pathogenic and, perhaps in some cases, protective (e.g., R268C) effects. PMID:24830383

  3. A novel missense mutation in oncostatin M receptor beta causing primary localized cutaneous amyloidosis.

    PubMed

    Saeedi, Marjan; Ebrahim-Habibi, Azadeh; Haghighi, Alireza; Zarrabi, Fariba; Amoli, Mahsa M; Robati, Reza M

    2014-01-01

    Primary localized cutaneous amyloidosis (PLCA) is a chronic skin disorder, caused by amyloid material deposition in the upper dermis. Autosomal dominant PLCA has been mapped earlier to pathogenic missense mutations in the OSMR gene, which encodes the oncostatin M receptor ß subunit (OSMRß). OSMRß is interleukin-6 family cytokine receptors and possesses two ligands, oncostatin M and interleukin-31, which both have biologic roles in inflammation and keratinocyte cell proliferation, differentiation, and apoptosis. Here, we identified a new OSMR mutation in a Kurdish family for the first time. Blood samples were taken from all the affected individuals in the family. DNA extraction was performed using salting out technique. Primers were designed for intron flanking individual exons of OSMR gene which were subjected to direct sequencing after PCR amplification for each sample. Sequencing showed a C/T substitution at position 613 in the proband. This mutation results in an L613S (leucine 613 to serine) amino acid change. The identified mutation was observed in all affected family members but not in 100 ethnically matched healthy controls. Elucidating the molecular basis of familial PLCA provides new insight into mechanisms of itch in human skin and may lead to new therapeutic targets for pruritus. PMID:25054142

  4. First missense mutation in the SOST gene causing sclerosteosis by loss of sclerostin function.

    PubMed

    Piters, Elke; Culha, Cavit; Moester, Martiene; Van Bezooijen, Rutger; Adriaensen, Dirk; Mueller, Thomas; Weidauer, Stella; Jennes, Karen; de Freitas, Fenna; Löwik, Clemens; Timmermans, Jean-Pierre; Van Hul, Wim; Papapoulos, Socrates

    2010-07-01

    Sclerosteosis is a rare bone dysplasia characterized by greatly increased bone mass, especially of the long bones and the skull. Patients are tall, show facial asymmetry and often have syndactyly. Clinical complications are due to entrapment of cranial nerves. The disease is thought to be due to loss-of-function mutations in the SOST gene. The SOST gene product, sclerostin, is secreted by osteocytes and transported to the bone surface where it inhibits osteoblastic bone formation by antagonizing Wnt signaling. In a small Turkish family with sclerosteosis, we identified a missense mutation (c.499T>C; p.Cys167Arg) in exon 2 of the SOST gene. This type of mutation has not been previously reported and using different functional approaches, we show that it has a devastating effect on the biological function of sclerostin. The affected cysteine is the last cysteine residue of the cystine-knot motif and loss of this residue leads to retention of the mutant protein in the ER, possibly as a consequence of impaired folding. Together with a significant reduced ability to bind to LRP5 and inhibit Wnt signaling, the p.Cys167Arg mutation leads to a complete loss of function of sclerostin and thus to the characteristic sclerosteosis phenotype. PMID:20583295

  5. [Recurrent European missense mutation in a Hungarian pedigree with Papillon-Lefèvre syndrome].

    PubMed

    Vályi, Péter; Farkas, Katalin; Tripolszki, Kornélia; Sulák, Adrienn; Széll, Márta; Nagy, Nikoletta; Nagy, Katalin

    2014-09-01

    Papillon-Lefèvre syndrome, a rare disease with autosomal recessive inheritance, is characterized by aggressive periodontitis and palmoplantar hyperkeratosis. Mutations of the cathepsin C gene are responsible for the development of the disease. In this study, we aimed to describe in details the clinical symptoms and to determine the underlying genetic abnormality in two Hungarian siblings affected by Papillon-Lefèvre syndrome. The siblings are under regular dental and dermatological care since their symptoms appeared, but, due to the fact that genetic analysis of Papillon-Lefèvre syndrome has been available for one or two years in Hungary, their mutation screenings were just recently performed. We have identified a homozygous missense mutation on the cathepsin C gene, which is an already published mutation and was originally reported from Germany. Our investigations would like to draw attention to a rare disease, Papillon-Lefèvre syndrome, in which first symptom can be the aggressive periodontitis, and in which genetic testing and for helping child-bearing and family planning is now available. PMID:25509509

  6. Establishing Precise Evolutionary History of a Gene Improves Predicting Disease Causing Missense Mutations

    PubMed Central

    Adebali, Ogun; Reznik, Alexander O.; Ory, Daniel S.; Zhulin, Igor B.

    2015-01-01

    Purpose Predicting the phenotypic effects of mutations has become an important application in clinical genetic diagnostics. Computational tools evaluate the behavior of the variant over evolutionary time and assume that variations seen during the course of evolution are likely benign in humans. However, current tools do not take into account orthologous/paralogous relationships. Paralogs have dramatically different roles in Mendelian diseases. For example, while inactivating mutations in the NPC1 gene cause the neurodegenerative disorder Niemann-Pick C, inactivating mutations in its paralog NPC1L1 are not disease-causing and moreover are implicated in protection from coronary heart disease. Methods We identified major events in NPC1 evolution and revealed and compared orthologs and paralogs of the human NPC1 gene through phylogenetic and protein sequence analyses. We predicted whether an amino acid substitution affects protein function by reducing the organism’s fitness. Results Removing the paralogs and distant homologs improved the overall performance of categorizing disease-causing and benign amino acid substitutions. Conclusion The results show that a thorough evolutionary analysis followed by identification of orthologs improves the accuracy in predicting disease-causing missense mutations. We anticipate that this approach will be used as a reference in the interpretation of variants in other genetic diseases as well. PMID:26890452

  7. Alpha-tubulin missense mutations correlate with antimicrotubule drug resistance in Eleusine indica.

    PubMed Central

    Yamamoto, E; Zeng, L; Baird, W V

    1998-01-01

    Dinitroaniline herbicides are antimicrotubule drugs that bind to tubulins and inhibit polymerization. As a result of repeated application of dinitroaniline herbicides, highly resistant and intermediately resistant biotypes of goosegrass (Eleusine indica) developed in previously wild-type populations. Three alpha-tubulin cDNA classes (designated TUA1, TUA2, and TUA3) were isolated from each biotype. Nucleotide differences between the susceptible and the resistant (R) alpha-tubulins were identified in TUA1 and TUA2. The most significant differences were missense mutations that occurred in TUA1 of the R and intermediately resistant (I) biotypes. Such mutations convert Thr-239 to Ile in the R biotype and Met-268 to Thr in the I biotype. These amino acid substitutions alter hydrophobicity; therefore, they may alter the dinitroaniline binding property of the protein. These mutations were correlated with the dinitroaniline response phenotypes (Drp). Plants homozygous for susceptibility possessed the wild-type TUA1 allele; plants homozygous for resistance possessed the mutant tua1 allele; and plants heterozygous for susceptibility possessed both wild-type and mutant alleles. Thus, we conclude that TUA1 is at the Drp locus. Using polymerase chain reaction primer-introduced restriction analysis, we demonstrated that goosegrass genomic DNA can be diagnosed for Drp alleles. Although not direct proof, these results suggest that a mutation in an alpha-tubulin gene confers resistance to dinitroanilines in goosegrass. PMID:9490751

  8. Hypomyelinating leukodystrophy-associated missense mutation in HSPD1 blunts mitochondrial dynamics

    SciTech Connect

    Miyamoto, Yuki; Eguchi, Takahiro; Kawahara, Kazuko; Hasegawa, Nanami; Nakamura, Kazuaki; Funakoshi-Tago, Megumi; Tanoue, Akito; Tamura, Hiroomi; Yamauchi, Junji

    2015-07-03

    Myelin-forming glial cells undergo dynamic morphological changes in order to produce mature myelin sheaths with multiple layers. In the central nervous system (CNS), oligodendrocytes differentiate to insulate neuronal axons with myelin sheaths. Myelin sheaths play a key role in homeostasis of the nervous system, but their related disorders lead not only to dismyelination and repeated demyelination but also to severe neuropathies. Hereditary hypomyelinating leukodystrophies (HLDs) are a group of such diseases affecting oligodendrocytes and are often caused by missense mutations of the respective responsible genes. Despite increasing identification of gene mutations through advanced nucleotide sequencing technology, studies on the relationships between gene mutations and their effects on cellular and subcellular aberrance have not followed at the same rapid pace. In this study, we report that an HLD4-associated (Asp-29-to-Gly) mutant of mitochondrial heat shock 60-kDa protein 1 (HSPD1) causes short-length morphologies and increases the numbers of mitochondria due to their aberrant fission and fusion cycles. In experiments using a fluorescent dye probe, this mutation decreases the mitochondrial membrane potential. Also, mitochondria accumulate in perinuclear regions. HLD4-associated HSPD1 mutant blunts mitochondrial dynamics, probably resulting in oligodendrocyte malfunction. This study constitutes a first finding concerning the relationship between disease-associated HSPD1 mutation and mitochondrial dynamics, which may be similar to the relationship between another disease-associated HSPD1 mutation (MitCHAP-60 disease) and aberrant mitochondrial dynamics. - Highlights: • The HLD4 mutant of HSPD1 decreases mitochondrial fission frequency. • The HLD4 mutant decreases mitochondrial fusion frequency. • Mitochondria harboring the HLD4 mutant exhibit slow motility. • The HLD4 mutant of HSPD1 decreases mitochondrial membrane potential. • HLD4-related diseases may

  9. The molecular basis of variable phenotypic severity among common missense mutations causing Rett syndrome.

    PubMed

    Brown, Kyla; Selfridge, Jim; Lagger, Sabine; Connelly, John; De Sousa, Dina; Kerr, Alastair; Webb, Shaun; Guy, Jacky; Merusi, Cara; Koerner, Martha V; Bird, Adrian

    2016-02-01

    Rett syndrome is caused by mutations in the X-linked MECP2 gene, which encodes a chromosomal protein that binds to methylated DNA. Mouse models mirror the human disorder and therefore allow investigation of phenotypes at a molecular level. We describe an Mecp2 allelic series representing the three most common missense Rett syndrome (RTT) mutations, including first reports of Mecp2[R133C] and Mecp2[T158M] knock-in mice, in addition to Mecp2[R306C] mutant mice. Together these three alleles comprise ∼25% of all RTT mutations in humans, but they vary significantly in average severity. This spectrum is mimicked in the mouse models; R133C being least severe, T158M most severe and R306C of intermediate severity. Both R133C and T158M mutations cause compound phenotypes at the molecular level, combining compromised DNA binding with reduced stability, the destabilizing effect of T158M being more severe. Our findings contradict the hypothesis that the R133C mutation exclusively abolishes binding to hydroxymethylated DNA, as interactions with DNA containing methyl-CG, methyl-CA and hydroxymethyl-CA are all reduced in vivo. We find that MeCP2[T158M] is significantly less stable than MeCP2[R133C], which may account for the divergent clinical impact of the mutations. Overall, this allelic series recapitulates human RTT severity, reveals compound molecular aetiologies and provides a valuable resource in the search for personalized therapeutic interventions. PMID:26647311

  10. Population-Based Estimate of Prostate Cancer Risk for Carriers of the HOXB13 Missense Mutation G84E

    PubMed Central

    Baglietto, Laura; Dowty, James G.; Jenkins, Mark A.; Southey, Melissa C.; Hopper, John L.; Giles, Graham G.

    2013-01-01

    The HOXB13 missense mutation G84E (rs138213197) is associated with increased risk of prostate cancer, but the current estimate of increased risk has a wide confidence interval (width of 95% confidence interval (CI) >200-fold) so the point estimate of 20-fold increased risk could be misleading. Population-based family studies can be more informative for estimating risks for rare variants, therefore, we screened for mutations in an Australian population-based series of early-onset prostate cancer cases (probands). We found that 19 of 1,384 (1.4%) probands carried the missense mutation, and of these, six (32%) had a family history of prostate cancer. We tested the 22 relatives of carriers diagnosed from 1998 to 2008 for whom we had a DNA sample, and found seven more carriers and one obligate carrier. The age-specific incidence for carriers was estimated to be, on average, 16.4 (95% CI 2.5–107.2) times that for the population over the time frame when the relatives were at risk prior to baseline. We then estimated the age and birth year- specific cumulative risk of prostate cancer (penetrance) for carriers. For example, the penetrance for an unaffected male carrier born in 1950 was 19% (95% CI 5–46%) at age 60 years, 44% (95% CI 18–74%) at age 70 years and 60% (95% CI 30–85%) at age 80 years. Our study has provided a population-based estimate of the average risk of prostate cancer for HOXB13 missense mutation G84E carriers that can be used to guide clinical practice and research. This study has also shown that the majority of hereditary prostate cancers due to the HOXB13 missense mutation are ‘sporadic’ in the sense that unselected cases with the missense mutation do not typically report having a family history of prostate cancer. PMID:23457453

  11. Ataxia-Pancytopenia Syndrome Is Caused by Missense Mutations in SAMD9L.

    PubMed

    Chen, Dong-Hui; Below, Jennifer E; Shimamura, Akiko; Keel, Sioban B; Matsushita, Mark; Wolff, John; Sul, Youngmee; Bonkowski, Emily; Castella, Maria; Taniguchi, Toshiyasu; Nickerson, Deborah; Papayannopoulou, Thalia; Bird, Thomas D; Raskind, Wendy H

    2016-06-01

    Ataxia-pancytopenia (AP) syndrome is characterized by cerebellar ataxia, variable hematologic cytopenias, and predisposition to marrow failure and myeloid leukemia, sometimes associated with monosomy 7. Here, in the four-generation family UW-AP, linkage analysis revealed four regions that provided the maximal LOD scores possible, one of which was in a commonly microdeleted chromosome 7q region. Exome sequencing identified a missense mutation (c.2640C>A, p.His880Gln) in the sterile alpha motif domain containing 9-like gene (SAMD9L) that completely cosegregated with disease. By targeted sequencing of SAMD9L, we subsequently identified a different missense mutation (c.3587G>C, p.Cys1196Ser) in affected members of the first described family with AP syndrome, Li-AP. Neither variant is reported in the public databases, both affect highly conserved amino acid residues, and both are predicted to be damaging. With time in culture, lymphoblastic cell lines (LCLs) from two affected individuals in family UW-AP exhibited copy-neutral loss of heterozygosity for large portions of the long arm of chromosome 7, resulting in retention of only the wild-type SAMD9L allele. Newly established LCLs from both individuals demonstrated the same phenomenon. In addition, targeted capture and sequencing of SAMD9L in uncultured blood DNA from both individuals showed bias toward the wild-type allele. These observations indicate in vivo hematopoietic mosaicism. The hematopoietic cytopenias that characterize AP syndrome and the selective advantage for clones that have lost the mutant allele support the postulated role of SAMD9L in the regulation of cell proliferation. Furthermore, we show that AP syndrome is distinct from the dyskeratoses congenita telomeropathies, with which it shares some clinical characteristics. PMID:27259050

  12. A germline missense mutation in COQ6 is associated with susceptibility to familial schwannomatosis

    PubMed Central

    Zhang, Keqiang; Lin, Jia-Wei; Wang, Jinhui; Wu, Xiwei; Gao, Hanlin; Hsieh, Yi-Chen; Hwu, Peter; Liu, Yun-Ru; Su, Leila; Chiou, Hung-Yi; Wang, Daidong; Yuan, Yate-Ching; Whang-Peng, Jacqueline; Chiu, Wen-Ta; Yen, Yun

    2014-01-01

    Purpose: Schwannomatosis, a subtype of neurofibromatosis, is characterized by multiple benign, nonvestibular, nonintradermal schwannomas. Although the tumor suppressor SMARCB1 gene has been frequently identified as the underlying genetic cause of half of familial and ~10% of sporadic schwannomatosis, for most other cases, further causative genes remain to be discovered. Herein, we characterize the genome of a schwannomatosis family without constitutional inactivation of the SMARCB1 gene to explore novel genomic alterations predisposing individuals to the familial disease. Methods: We performed whole-genome/exome sequencing on genomic DNA of both schwannomatosis-affected and normal members of the family. Results: We identified a novel missense mutation (p.Asp208His; c.622G>C) in the coenzyme Q10 (CoQ10) biosynthesis monooxygenase 6 gene (COQ6) in schwannomatosis-affected members. The deleterious effects of the COQ6 mutations were validated by their lack of complementation in a coq6-deficient yeast mutant. Our study further indicated that the resultant haploinsufficiency of COQ6 might lead to CoQ10 deficiency and chronic overproduction of reactive oxygen species in Schwann cells. Conclusion: Although the exact oncogenetic mechanisms in this schwannomatosis family remain to be elucidated, our data strongly indicate a probable role of COQ6 mutation and CoQ10 deficiency in the development of familial schwannomatosis. PMID:24763291

  13. A novel MVK missense mutation in one Chinese family with disseminated superficial actinic porokeratosis.

    PubMed

    Lu, Wen-sheng; Zheng, Xiao-dong; Yao, Xiu-hua; Zhang, Lan-fang; Wang, Mu-Qiu; Jiang, Fa-Xing; Zhang, Si-Ping; Hu, Bai

    2014-11-01

    Disseminated superficial actinic porokeratosis (DSAP) is a severe chronic autosomal dominant cutaneous disorder with high genetic heterogeneity. mevalonate kinase, (MVK) a gene know to play an important role in regulation of calcium-induced keratinocyte differentiation and proliferation, has recently been suggested as the disease-causing gene for DSAP. Here we report a direct sequencing analysis of this gene in 3 DSAP families, 6 sporadic cases, and 100 unrelated healthy controls. We detected a heterozygous T to A transition at nucleotide 205 in exon 3 of MVK gene in one familial case. This mutation will result in an amino acid change at codon 69 (P.Ser69Thr), which is from a serine codon (TCA) to a threonine codon (ACA). No such mutation was detected in the unaffected family members or the 100 unrelated healthy controls. Our results demonstrated a novel missense mutation in MVK gene. This will be valuable for the diagnosis of DSAP as well as for genetic counseling and prenatal diagnosis of affected families. PMID:25059119

  14. Homozygous familial hypobetalipoproteinemia: A Turkish case carrying a missense mutation in apolipoprotein B.

    PubMed

    Yilmaz, Berna Seker; Mungan, Neslihan Onenli; Di Leo, Enza; Magnolo, Lucia; Artuso, Lucia; Bernardis, Isabella; Tumgor, Gokhan; Kor, Deniz; Tarugi, Patrizia

    2016-01-15

    The autosomal co-dominant disorder familial hypobetalipoproteinemia (FHBL) may be due to mutations in the APOB gene encoding apolipoprotein B (apoB), the main constituent peptide of chylomicrons, very low and low density lipoproteins. We describe an 11month-old child with failure to thrive, intestinal lipid malabsorption, hepatic steatosis and severe hypobetalipoproteinemia, suggesting the diagnosis of homozygous FHBL, abetalipoproteinemia (ABL) or chylomicron retention disease (CMRD). The analysis of candidate genes showed that patient was homozygous for a variant (c.1594 C>T) in the APOB gene causing arginine to tryptophan conversion at position 505 of mature apoB (Arg505Trp). No mutations were found in a panel of other potential candidate genes for hypobetalipoproteinemia. In vitro studies showed a reduced secretion of mutant apoB-48 with respect to the wild-type apoB-48 in transfected McA-RH7777 cells. The Arg505Trp substitution is located in the βα1 domain of apoB involved in the lipidation of apoB mediated by microsomal triglyceride transfer protein (MTP), the first step in VLDL and chylomicron formation. The patient's condition improved in response to a low fat diet supplemented with fat-soluble vitamins. Homozygosity for a rare missense mutation in the βα1 domain of apoB may be the cause of both severe hypobetalipoproteinemia and intestinal lipid malabsorption. PMID:26612772

  15. Missense mutations in the perforin (PRF1) gene as a cause of hereditary cancer predisposition.

    PubMed

    Chaudhry, Mohammed S; Gilmour, Kimberly C; House, Imran G; Layton, Mark; Panoskaltsis, Nicki; Sohal, Mamta; Trapani, Joseph A; Voskoboinik, Ilia

    2016-07-01

    Perforin, a pore-forming toxin released from secretory granules of NK cells and CTLs, is essential for their cytotoxic activity against infected or cancerous target cells. Bi-allelic loss-of-function mutations in the perforin gene are invariably associated with a fatal immunoregulatory disorder, familial haemophagocytic lymphohistiocytosis type 2 (FHL2), in infants. More recently, it has also been recognized that partial loss of perforin function can cause disease in later life, including delayed onset FHL2 and haematological malignancies. Herein, we report a family in which a wide range of systemic inflammatory and neoplastic manifestations have occurred across three generations. We found that disease was linked to two missense perforin gene mutations (encoding A91V, R410W) that cause protein misfolding and partial loss of activity. These cases link the partial loss of perforin function with some solid tumors that are known to be controlled by the immune system, as well as haematological cancers. Our findings also demonstrate that perforin gene mutations can contribute to hereditary cancer predisposition. PMID:27622035

  16. Laminin β2 gene missense mutation produces endoplasmic reticulum stress in podocytes.

    PubMed

    Chen, Ying Maggie; Zhou, Yuefang; Go, Gloriosa; Marmerstein, Joseph T; Kikkawa, Yamato; Miner, Jeffrey H

    2013-07-01

    Mutations in the laminin β2 gene (LAMB2) cause Pierson syndrome, a severe congenital nephrotic syndrome with ocular and neurologic defects. LAMB2 is a component of the laminin-521 (α5β2γ1) trimer, an important constituent of the glomerular basement membrane (GBM). The C321R-LAMB2 missense mutation leads to congenital nephrotic syndrome but only mild extrarenal symptoms; the mechanisms underlying the development of proteinuria with this mutation are unclear. We generated three transgenic mouse lines, in which rat C321R-LAMB2 replaced mouse LAMB2 in the GBM. During the first postnatal month, expression of C321R-LAMB2 attenuated the severe proteinuria exhibited by Lamb2(-/-) mice in a dose-dependent fashion; proteinuria eventually increased, however, leading to renal failure. The C321R mutation caused defective secretion of laminin-521 from podocytes to the GBM accompanied by podocyte endoplasmic reticulum (ER) stress, likely resulting from protein misfolding. Moreover, ER stress preceded the onset of significant proteinuria and was manifested by induction of the ER-initiated apoptotic signal C/EBP homologous protein (CHOP), ER distention, and podocyte injury. Treatment of cells expressing C321R-LAMB2 with the chemical chaperone taurodeoxycholic acid (TUDCA), which can facilitate protein folding and trafficking, greatly increased the secretion of the mutant LAMB2. Taken together, these results suggest that the mild variant of Pierson syndrome caused by the C321R-LAMB2 mutation may be a prototypical ER storage disease, which may benefit from treatment approaches that target the handling of misfolded proteins. PMID:23723427

  17. A Missense Mutation in PPARD Causes a Major QTL Effect on Ear Size in Pigs

    PubMed Central

    Ren, Jun; Duan, Yanyu; Qiao, Ruimin; Yao, Fei; Zhang, Zhiyan; Yang, Bin; Guo, Yuanmei; Xiao, Shijun; Wei, Rongxin; Ouyang, Zixuan; Ding, Nengshui; Ai, Huashui; Huang, Lusheng

    2011-01-01

    Chinese Erhualian is the most prolific pig breed in the world. The breed exhibits exceptionally large and floppy ears. To identify genes underlying this typical feature, we previously performed a genome scan in a large scale White Duroc × Erhualian cross and mapped a major QTL for ear size to a 2-cM region on chromosome 7. We herein performed an identical-by-descent analysis that defined the QTL within a 750-kb region. Historically, the large-ear feature has been selected for the ancient sacrificial culture in Erhualian pigs. By using a selective sweep analysis, we then refined the critical region to a 630-kb interval containing 9 annotated genes. Four of the 9 genes are expressed in ear tissues of piglets. Of the 4 genes, PPARD stood out as the strongest candidate gene for its established role in skin homeostasis, cartilage development, and fat metabolism. No differential expression of PPARD was found in ear tissues at different growth stages between large-eared Erhualian and small-eared Duroc pigs. We further screened coding sequence variants in the PPARD gene and identified only one missense mutation (G32E) in a conserved functionally important domain. The protein-altering mutation showed perfect concordance (100%) with the QTL genotypes of all 19 founder animals segregating in the White Duroc × Erhualian cross and occurred at high frequencies exclusively in Chinese large-eared breeds. Moreover, the mutation is of functional significance; it mediates down-regulation of β-catenin and its target gene expression that is crucial for fat deposition in skin. Furthermore, the mutation was significantly associated with ear size across the experimental cross and diverse outbred populations. A worldwide survey of haplotype diversity revealed that the mutation event is of Chinese origin, likely after domestication. Taken together, we provide evidence that PPARD G32E is the variation underlying this major QTL. PMID:21573137

  18. Report of a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris phenotype, and schwannomatosis.

    PubMed

    Gossai, Nathan; Biegel, Jaclyn A; Messiaen, Ludwine; Berry, Susan A; Moertel, Christopher L

    2015-12-01

    We report a patient with a constitutional missense mutation in SMARCB1, Coffin-Siris Syndrome (CSS), and schwannomatosis. CSS is a rare congenital syndrome with characteristic clinical findings. This thirty-three-year-old man was diagnosed early in life with the constellation of moderate intellectual disability, hypotonia, mild microcephaly, coarse facies, wide mouth with full lips, hypoplasia of the digits, and general hirsutism. At age 26, he was found to have schwannomatosis after presenting with acute spinal cord compression. Blood and tissue analysis of multiple subsequent schwannoma resections revealed a germline missense mutation of SMARCB1, acquired loss of 22q including SMARCB1 and NF2 and mutation of the remaining NF2 wild-type allele-thus completing the four-hit, three-event mechanism associated with schwannomatosis. Variations in five genes have been associated with the Coffin-Siris phenotype: ARID1A, ARID1B, SMARCA4, SMARCB1, and SMARCE1. Of these genes, SMARCB1 has a well-established association with schwannomatosis and malignancy. This is the first report of a patient with a constitutional missense mutation of SMARCB1 resulting in CSS and subsequent development of schwannomatosis. This finding demonstrates that a SMARCB1 mutation may be the initial "hit" (constitutional) for a genetic disorder with subsequent risk of developing schwannomas and other malignancies, and raises the possibility that other patients with switch/sucrose non-fermenting (SWI/SNF) mutations may be at increased risk for tumors. PMID:26364901

  19. Severe G6PD Deficiency Due to a New Missense Mutation in an Infant of Northern European Descent.

    PubMed

    Warny, Marie; Lausen, Birgitte; Birgens, Henrik; Knabe, Niels; Petersen, Jesper

    2015-11-01

    We report a term male infant born to parents of Danish descent, who on the second day of life developed jaundice peaking at 67 hours and decreasing on applied double-sided phototherapy. In the weeks following, the infant showed signs of ongoing hemolysis. Laboratory tests showed very low glucose-6-phosphate dehydrogenase (G6PD) enzymatic activity, and sequencing of the G6PD gene revealed a previously uncharacterized missense mutation c. 592 C>A (Arg198Ser). Oral DNA from the infant had the same G6PD mutation, suggesting a spontaneous maternal germline mutation as the mutation was not observed in leukocytes from the mother. PMID:26479991

  20. A COLQ Missense Mutation in Sphynx and Devon Rex Cats with Congenital Myasthenic Syndrome

    PubMed Central

    Abitbol, Marie; Hitte, Christophe; Bossé, Philippe; Blanchard-Gutton, Nicolas; Thomas, Anne; Martignat, Lionel; Blot, Stéphane; Tiret, Laurent

    2015-01-01

    An autosomal recessive neuromuscular disorder characterized by skeletal muscle weakness, fatigability and variable electromyographic or muscular histopathological features has been described in the two related Sphynx and Devon Rex cat breeds (Felis catus). Collection of data from two affected Sphynx cats and their relatives pointed out a single disease candidate region on feline chromosome C2, identified following a genome-wide SNP-based homozygosity mapping strategy. In that region, we further identified COLQ (collagen-like tail subunit of asymmetric acetylcholinesterase) as a good candidate gene, since COLQ mutations were identified in affected humans and dogs with endplate acetylcholinesterase deficiency leading to a synaptic form of congenital myasthenic syndrome (CMS). A homozygous c.1190G>A missense variant located in exon 15 of COLQ, leading to a C397Y substitution, was identified in the two affected cats. C397 is a highly-conserved residue from the C-terminal domain of the protein; its mutation was previously shown to produce CMS in humans, and here we confirmed in an affected Sphynx cat that it induces a loss of acetylcholinesterase clustering at the neuromuscular junction. Segregation of the c.1190G>A variant was 100% consistent with the autosomal recessive mode of inheritance of the disorder in our cat pedigree; in addition, an affected, unrelated Devon Rex cat recruited thereafter was also homozygous for the variant. Genotyping of a panel of 333 cats from 14 breeds failed to identify a single carrier in non-Sphynx and non-Devon Rex cats. Finally, the percentage of healthy carriers in a European subpanel of 81 genotyped Sphynx cats was estimated to be low (3.7%) and 14 control Devon Rex cats were genotyped as wild-type individuals. Altogether, these results strongly support that the neuromuscular disorder reported in Sphynx and Devon Rex breeds is a CMS caused by a unique c.1190G>A missense mutation, presumably transmitted through a founder effect, which

  1. Dyslexia and DYX1C1: deficits in reading and spelling associated with a missense mutation.

    PubMed

    Bates, T C; Lind, P A; Luciano, M; Montgomery, G W; Martin, N G; Wright, M J

    2010-12-01

    The status of DYX1C1 (C15q21.3) as a susceptibility gene for dyslexia is unclear. We report the association of this gene with reading and spelling ability in a sample of adolescent twins and their siblings. Family-based association analyses were carried out on 13 single-nucleotide polymorphisms (SNPs) in DYX1C1, typed in 790 families with up to 5 offspring and tested on 6 validated measures of lexical processing (irregular word) and grapheme-phoneme decoding (pseudo-word) reading- and spelling-based measures of dyslexia, as well as a short-term memory measure. Significant association was observed at the misssense mutation rs17819126 for all reading measures and for spelling of lexical processing words, and at rs3743204 for both irregular and nonword reading. Verbal short-term memory was associated with rs685935. Support for association was not found at rs3743205 and rs61761345 as previously reported by Taipale et al., but these SNPs had very low (0.002 for rs3743205) minor allele frequencies in this sample. These results suggest that DYX1C1 influences reading and spelling ability with additional effects on short-term information storage or rehearsal. Missense mutation rs17819126 is a potential functional basis for the association of DYX1C1 with dyslexia. PMID:19901951

  2. Harderoporphyria due to homozygosity for coproporphyrinogen oxidase missense mutation H327R.

    PubMed

    Hasanoglu, Alev; Balwani, Manisha; Kasapkara, Ciğdem S; Ezgü, Fatih S; Okur, Ilyas; Tümer, Leyla; Cakmak, Alpay; Nazarenko, Irina; Yu, Chunli; Clavero, Sonia; Bishop, David F; Desnick, Robert J

    2011-02-01

    Hereditary coproporphyria (HCP) is an autosomal dominant acute hepatic porphyria due to the half-normal activity of the heme biosynthetic enzyme, coproporphyrinogen oxidase (CPOX). The enzyme catalyzes the step-wise oxidative decarboxylation of the heme precursor, coproporphyrinogen III, to protoporphyrinogen IX via a tricarboxylic intermediate, harderoporphyrinogen. In autosomal dominant HCP, the deficient enzymatic activity results primarily in the accumulation of coproporphyrin III. To date, only a few homozygous HCP patients have been described, most having Harderoporphyria, a rare variant due to specific CPOX mutations that alter enzyme residues D400-K404, most patients described to date having at least one K404E allele. Here, we describe a Turkish male infant, the product of a consanguineous union, who presented with the Harderoporphyria phenotype including neonatal hyperbilirubinemia, hemolytic anemia, hepatosplenomegaly, and skin lesions when exposed to UV light. He was homoallelic for the CPOX missense mutation, c.980A>G (p.H327R), and had massively increased urinary uroporphyrins I and III (9,250 and 2,910 μM, respectively) and coproporphyrins I and III (895 and 19,400 μM, respectively). The patient expired at 5 months of age from an apparent acute neurologic porphyric attack. Structural studies predicted that p.H327R interacts with residue W399 in the CPOX active site, thereby accounting for the Harderoporphyria phenotype. PMID:21103937

  3. HARDEROPORPHYRIA DUE TO HOMOZYGOSITY FOR COPROPORPHYRINOGEN OXIDASE MISSENSE MUTATION H327R

    PubMed Central

    Hasanoglu, A; Balwani, M; Kasapkara, ÇS; Ezgü, FS; Okur, I; Tümer, L; Çakmak, A; Nazarenko, I; Yu, C; Clavero, S; Bishop, DF; Desnick, RJ

    2011-01-01

    Summary Hereditary coproporphyria (HCP) is an autosomal dominant acute hepatic porphyria due to the half-normal activity of the heme biosynthetic enzyme, coproporphyrinogen oxidase (CPOX). The enzyme catalyzes the step-wise oxidative decarboxylation of the heme precursor, coproporphyrinogen III to protoporphyrinogen IX via a tricarboxylic intermediate, harderoporphyrinogen. In autosomal dominant HCP, the deficient enzymatic activity results primarily in the accumulation of coproporphyrin III. To date, only a few homozygous HCP patients have been described, most having Harderoporphyria, a rare variant due to specific CPOX mutations that alter enzyme residues D400-K404, most patients described to date having at least one K404E allele. Here, we describe a Turkish male infant, the product of a consanguineous union, who presented with the Harderoporphyria phenotype including neonatal hyperbilirubinemia, hemolytic anemia, hepatosplenomegaly, and skin lesions when exposed to UV light. He was homoallelic for the CPOX missense mutation, c.980A>G (p.H327R), and had massively increased urinary uroporphyrins I and III (9250 and 2910 μM, respectively) and coproporphyrins I and III (895 and 19,400 μM, respectively). The patient expired at five months of age from an apparent acute neurologic porphyric attack. Structural studies predicted that p.H327R interacts with residue W399 in the CPOX active site, thereby accounting for the Harderoporphyria phenotype. PMID:21103937

  4. A new missense mutation in the BCKDHB gene causes the classic form of maple syrup urine disease (MSUD).

    PubMed

    Miryounesi, Mohammad; Ghafouri-Fard, Soudeh; Goodarzi, Hamedreza; Fardaei, Majid

    2015-05-01

    Maple syrup urine disease (MSUD) is an autosomal recessive metabolic disease caused by mutations in the BCKDHA, BCKDHB, DBT and DLD genes, which encode the E1α, E1β, E2 and E3 subunits of the branched chain α ketoacid dehydrogenase (BCKD) complex, respectively. This complex is involved in the metabolism of branched-chain amino acids. In this study, we analyzed the DNA sequences of BCKDHA and BCKDHB genes in an infant who suffered from MSUD and died at the age of 6 months. We found a new missense mutation in exon 5 of BCKDHB gene (c.508C>T). The heterozygosity of the parents for the mentioned nucleotide change was confirmed by direct sequence analysis of the corresponding segment. Another missense mutation has been found in the same codon previously and shown by in silico analyses to be deleterious. This report provides further evidence that this amino acid change can cause classic MSUD. PMID:25381949

  5. Whole-exome sequencing identifies a somatic missense mutation of NBN in clear cell sarcoma of the salivary gland.

    PubMed

    Zhang, Lei; Jia, Zhen; Mao, Fengbiao; Shi, Yueyi; Bu, Rong Fa; Zhang, Baorong

    2016-06-01

    Clear cell sarcoma (CCS) is a rare, low-grade carcinoma commonly located in the distal extremities of young adults involving tendons and aponeuroses. CCS is characterized by its poor prognosis due to late diagnosis, multiple local recurrence, propensity to late metastases, and a high rate of tumor-related mortality. The genetic cause for CCS is thought to be EWSR1 gene translocation. However, CCS lacking a translocation may have other, as yet uncharacterized, genetic mutations that can cause the same pathological effect. A combination of whole‑exome sequencing and Sanger sequencing of cancer tissue and venous blood from a patient diagnosed with CCS of the salivary gland revealed a somatic missense mutation, c.1061C>T (p.P354L), in exon 9 of the Nibrin gene (NBN). This somatic missense mutation led to the conversion of proline to leucine (p.P354L), resulting in deleterious effects for the NBN protein. Multiple-sequence alignments showed that codon 354, where the mutation (c.1061C>T) occurs, is located within a phylogenetically conserved region. In conclusion, we here report a somatic missense mutation c.1061C>T (p.P354L) in the NBN gene in a patient with CCS lacking an EWSR1-ATF1 fusion. Our findings broaden the genotypic spectrum of CCS and provide new molecular insight that should prove useful in the future clinical genetic diagnosis of CCS. PMID:27109316

  6. Mice with missense and nonsense NF1 mutations display divergent phenotypes compared with human neurofibromatosis type I

    PubMed Central

    Li, Kairong; Turner, Ashley N.; Chen, Min; Brosius, Stephanie N.; Schoeb, Trenton R.; Messiaen, Ludwine M.; Bedwell, David M.; Zinn, Kurt R.; Anastasaki, Corina; Gutmann, David H.; Korf, Bruce R.

    2016-01-01

    ABSTRACT Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by the occurrence of nerve sheath tumors and considerable clinical heterogeneity. Some translational studies have been limited by the lack of animal models available for assessing patient-specific mutations. In order to test therapeutic approaches that might restore function to the mutated gene or gene product, we developed mice harboring NF1 patient-specific mutations including a nonsense mutation (c.2041C>T; p.Arg681*) and a missense mutation (c.2542G>C; p.Gly848Arg). The latter is associated with the development of multiple plexiform neurofibromas along spinal nerve roots. We demonstrate that the human nonsense NF1Arg681* and missense NF1Gly848Arg mutations have different effects on neurofibromin expression in the mouse and each recapitulates unique aspects of the NF1 phenotype, depending upon the genetic context when assessed in the homozygous state or when paired with a conditional knockout allele. Whereas the missense Nf1Gly848Arg mutation fails to produce an overt phenotype in the mouse, animals homozygous for the nonsense Nf1Arg681* mutation are not viable. Mice with one Nf1Arg681* allele in combination with a conditional floxed Nf1 allele and the DhhCre transgene (Nf14F/Arg681*; DhhCre) display disorganized nonmyelinating axons and neurofibromas along the spinal column, which leads to compression of the spinal cord and paralysis. This model will be valuable for preclinical testing of novel nonsense suppression therapies using drugs to target in-frame point mutations that create premature termination codons in individuals with NF1. PMID:27482814

  7. Mice with missense and nonsense NF1 mutations display divergent phenotypes compared with human neurofibromatosis type I.

    PubMed

    Li, Kairong; Turner, Ashley N; Chen, Min; Brosius, Stephanie N; Schoeb, Trenton R; Messiaen, Ludwine M; Bedwell, David M; Zinn, Kurt R; Anastasaki, Corina; Gutmann, David H; Korf, Bruce R; Kesterson, Robert A

    2016-07-01

    Neurofibromatosis type 1 (NF1) is a common genetic disorder characterized by the occurrence of nerve sheath tumors and considerable clinical heterogeneity. Some translational studies have been limited by the lack of animal models available for assessing patient-specific mutations. In order to test therapeutic approaches that might restore function to the mutated gene or gene product, we developed mice harboring NF1 patient-specific mutations including a nonsense mutation (c.2041C>T; p.Arg681*) and a missense mutation (c.2542G>C; p.Gly848Arg). The latter is associated with the development of multiple plexiform neurofibromas along spinal nerve roots. We demonstrate that the human nonsense NF1(Arg681*) and missense NF1(Gly848Arg) mutations have different effects on neurofibromin expression in the mouse and each recapitulates unique aspects of the NF1 phenotype, depending upon the genetic context when assessed in the homozygous state or when paired with a conditional knockout allele. Whereas the missense Nf1(Gly848Arg) mutation fails to produce an overt phenotype in the mouse, animals homozygous for the nonsense Nf1(Arg681*) mutation are not viable. Mice with one Nf1(Arg681*) allele in combination with a conditional floxed Nf1 allele and the DhhCre transgene (Nf1(4F/Arg681*); DhhCre) display disorganized nonmyelinating axons and neurofibromas along the spinal column, which leads to compression of the spinal cord and paralysis. This model will be valuable for preclinical testing of novel nonsense suppression therapies using drugs to target in-frame point mutations that create premature termination codons in individuals with NF1. PMID:27482814

  8. A Novel Missense Mutation in ADAMTS10 in Norwegian Elkhound Primary Glaucoma

    PubMed Central

    Ahonen, Saija J.; Kaukonen, Maria; Nussdorfer, Forrest D.; Harman, Christine D.; Komáromy, András M.; Lohi, Hannes

    2014-01-01

    Primary glaucoma is one of the most common causes of irreversible blindness both in humans and in dogs. Glaucoma is an optic neuropathy affecting the retinal ganglion cells and optic nerve, and elevated intraocular pressure is commonly associated with the disease. Glaucoma is broadly classified into primary open angle (POAG), primary closed angle (PCAG) and primary congenital glaucoma (PCG). Human glaucomas are genetically heterogeneous and multiple loci have been identified. Glaucoma affects several dog breeds but only three loci and one gene have been implicated so far. We have investigated the genetics of primary glaucoma in the Norwegian Elkhound (NE). We established a small pedigree around the affected NEs collected from Finland, US and UK and performed a genome-wide association study with 9 cases and 8 controls to map the glaucoma gene to 750 kb region on canine chromosome 20 (praw = 4.93×10−6, pgenome = 0.025). The associated region contains a previously identified glaucoma gene, ADAMTS10, which was subjected to mutation screening in the coding regions. A fully segregating missense mutation (p.A387T) in exon 9 was found in 14 cases and 572 unaffected NEs (pFisher = 3.5×10−27) with a high carrier frequency (25.3%). The mutation interrupts a highly conserved residue in the metalloprotease domain of ADAMTS10, likely affecting its functional capacity. Our study identifies the genetic cause of primary glaucoma in NEs and enables the development of a genetic test for breeding purposes. This study establishes also a new spontaneous canine model for glaucoma research to study the ADAMTS10 biology in optical neuropathy. PMID:25372548

  9. Missense mutations and evolutionary conservation of amino acids: evidence that many of the amino acids in factor IX function as "spacer" elements.

    PubMed Central

    Bottema, C D; Ketterling, R P; Ii, S; Yoon, H S; Phillips, J A; Sommer, S S

    1991-01-01

    We report 31 point mutations in the factor IX gene and explore the relationship between the level of evolutionary conservation of an amino acid and the probability of a mutation causing hemophilia B. From our total sample of 125 hemophiliacs and from those reported by others, we identify 95 independent missense mutations, 94 of which occur at amino acids that are evolutionarily conserved in the available mammalian factor IX sequences. The likelihood of a missense mutation causing hemophilia B depends on whether the residue is also conserved in the factor IX-related proteases: factor VII, factor X, and protein C. Most of the possible missense mutations in generically conserved residues (i.e., those conserved in factor IX and in all the related proteases) should cause disease. In contrast, missense mutations in factor IX-specific residues (i.e., those conserved in human, cow, dog, and mouse factor IX but not in the related proteases) are sixfold less likely to cause disease. Missense mutations at nonconserved residues are 33-fold less likely to cause disease. At least three models are compatible with these observations. A comparison of sequence alignments from four and nine species of factor IX and an examination of the missense mutations occurring at CpG residues suggest a model in which most residues fall on opposite ends of a spectrum. In about 40% of residues, virtually any missense mutation in a minority of the residues will cause disease, while virtually no missense mutations will cause disease in most of the remaining residues. Thus, many of the residues in factor IX are spacers; that is, the main chains are presumably necessary to keep other amino acid interactions in register, but the nature of the side chain is unimportant. PMID:1680287

  10. Missense tau mutations identified in FTDP-17 have a small effect on tau-microtubule interactions.

    PubMed

    DeTure, M; Ko, L W; Yen, S; Nacharaju, P; Easson, C; Lewis, J; van Slegtenhorst, M; Hutton, M; Yen, S H

    2000-01-17

    Frontotemporal dementia with Parkinsonism linked to chromosome 17 (FTDP-17) is a group of related disorders frequently characterized by the formation of tau inclusions in neurons and glial cells. To determine whether the formation of tau inclusions in FTDP-17 results from an alteration in the ability of mutant tau to maintain the microtubule (MT) system, we compared wild type four-repeat tau with three FTDP-17 mutants (P301L, V337M and R406W) for their ability to bind MT, promote MT assembly and bundling. According to in vitro binding and assembly assays, P301L is the only mutant that demonstrates a small, yet significant reduction, in its affinity for MT while both P301L and R406W have a small reduction in their ability to promote tubulin assembly. Based on studies of neuroblastoma and CHO cells transfected with GFP-tagged tau DNA constructs, both mutant and wild type tau transfectants were indistinguishable in the distribution pattern of tau in terms of co-localization with MT and generation of MT bundles. These results suggest that missense mutation of tau gene do not have an immediate impact on the integrity of MT system, and that exposure of affected neurons to additional insults or factors (e.g., aging) may be needed to initiate the formation of tau inclusions in FTDP-17. PMID:10627302

  11. Missense mutation in the PTEN promoter of a patient with hemifacial hyperplasia

    PubMed Central

    Yamazaki, Kiyomi; Eng, Charis; Kuznetsov, Sergei A; Reinisch, John; Yamashita, Dennis-Duke; Walker, John; Cheung, Craig; Robey, Pamela G; Yen, Stephen L-K

    2015-01-01

    The cellular mechanisms involved in the asymmetric facial overgrowth syndrome, hemifacial hyperplasia (HFH), are not well understood. This study was conducted to compare primary cell cultures from hyperplastic and normal HFH bone for cellular and molecular differences. Primary cultures developed from biopsies of a patient with isolated HFH showed a twofold difference in cell size and cell number between hyperplastic and normal bone. Microarray data suggested a 40% suppression of PTEN (phosphatase-tensin homolog) transcripts. Sequencing of the PTEN gene and promoter identified novel C/G missense mutation (position −1053) in the regulatory region of the PTEN promoter. Western blots of downstream pathway components showed an increase in PKBa/Akt1 phosphorylation and TOR (target of rapamcyin) signal. Sirolimus, an inhibitor of TOR, when added to overgrowth cells reversed the cell size, cell number and total protein differences between hyperplastic and normal cells. In cases of facial overgrowth, which involve PTEN/Akt/TOR dysregulation, sirolimus could be used for limiting cell overgrowth. PMID:26229595

  12. A homozygous missense mutation in HERC2 associated with global developmental delay and autism spectrum disorder.

    PubMed

    Puffenberger, Erik G; Jinks, Robert N; Wang, Heng; Xin, Baozhong; Fiorentini, Christopher; Sherman, Eric A; Degrazio, Dominick; Shaw, Calvin; Sougnez, Carrie; Cibulskis, Kristian; Gabriel, Stacey; Kelley, Richard I; Morton, D Holmes; Strauss, Kevin A

    2012-12-01

    We studied a unique phenotype of cognitive delay, autistic behavior, and gait instability segregating in three separate sibships. We initiated genome-wide mapping in two sibships using Affymetrix 10K SNP Mapping Arrays and identified a homozygous 8.2 Mb region on chromosome 15 common to five affected children. We used exome sequencing of two affected children to assess coding sequence variants within the mapped interval. Four novel homozygous exome variants were shared between the two patients; however, only two variants localized to the mapped interval on chromosome 15. A third sibship in an Ohio Amish deme narrowed the mapped interval to 2.6 Mb and excluded one of the two novel homozygous exome variants. The remaining variant, a missense change in HERC2 (c.1781C>T, p.Pro594Leu), occurs in a highly conserved proline residue within an RCC1-like functional domain. Functional studies of truncated HERC2 in adherent retinal pigment epithelium cells suggest that the p.Pro594Leu variant induces protein aggregation and leads to decreased HERC2 abundance. The phenotypic correlation with the mouse Herc1 and Herc2 mutants as well as the phenotypic overlap with Angelman syndrome provide further evidence that pathogenic changes in HERC2 are associated with nonsyndromic intellectual disability, autism, and gait disturbance. Hum Mutat 33:1639-1646, 2012. © 2012 Wiley Periodicals, Inc. PMID:23065719

  13. A missense mutation in melanocortin 1 receptor is associated with the red coat colour in donkeys.

    PubMed

    Abitbol, M; Legrand, R; Tiret, L

    2014-12-01

    The seven donkey breeds recognised by the French studbook are characterised by few coat colours: black, bay and grey. Normand bay donkeys seldom give birth to red foals, a colour more commonly seen and recognised in American miniature donkeys. Red resembles the equine chestnut colour, previously attributed to a mutation in the melanocortin 1 receptor gene (MC1R). We used a panel of 124 donkeys to identify a recessive missense c.629T>C variant in MC1R that showed a perfect association with the red coat colour. This variant leads to a methionine to threonine substitution at position 210 in the protein. We showed that methionine 210 is highly conserved among vertebrate melanocortin receptors. Previous in silico and in vitro analyses predicted this residue to lie within a functional site. Our in vivo results emphasised the pivotal role played by this residue, the alteration of which yielded a phenotype fully compatible with a loss of function of MC1R. We thus propose to name the c.629T>C allele in donkeys the e allele, which further enlarges the panel of recessive MC1R loss-of-function alleles described in animals and humans. PMID:25155046

  14. Missense mutations in the adhalin gene linked to autosomal recessive muscular dystrophy

    SciTech Connect

    Roberds, S.L.; Anderson, R.D.; Lim, L.E.

    1994-09-01

    Adhalin, the 50-kDa dystrophin-associated glycoprotein, is deficient in skeletal muscle of patients having severe childhood autosomal recessive muscular dystrophy (SCARMD). In several North African families, SCARMD has been linked to markers in the pericentromeric region of chromosome l3q, but SCARMD has been excluded from linkage to this locus in other families. To determine whether the adhalin gene might be involved in SCARMD, human adhalin cDNA and large portions of the adhalin gene were cloned. Adhalin is a transmembrane glycoprotein with an extracellular domain bearing limited homology to domains of entactin and nerve growth factor receptor, suggesting that adhalin may serve as a receptor for an extracellular matrix protein. The adhalin gene was mapped to chromosome 17q12-q21.33, excluding the gene from involvement in 13q-linked SCARMD. A polymorphic microsatellite was identified within intron 6 of the adhalin gene, and one allelic variant of this marker cosegregated with the disease phenotype in a large French family with a lod score of 3.61 at 0 recombination. Adhalin is undetectable in skeletal muscle from affected members of this family. Missense mutations were identified within the adhalin gene that might cause SCARMD in this family. Thus, genetic defects in at least two components, dystrophin and adhalin, of the dystrophin-glycoprotein complex can independently cause muscular dystrophies.

  15. Absence of missense mutations in activated c-myc genes in avian leukosis virus-induced B-cell lymphomas

    SciTech Connect

    Hahn, M.; Hayward, W.S.

    1988-06-01

    The authors determined the nucleotide sequences of two independent DNA clones which contained the activated c-myc genes from avian leukosis virus-induced B-cell lymphomas. Neither of these c-myce genes contained missense mutations. This strongly supports the notion that the c-myc photo-oncogene in avian leukosis virus-induced B-cell lymphomas can be oncogenically activated by altered expression of the gene without a change in the primary structure of the gene product.

  16. Identification of I411K, a novel missense EYA4 mutation causing autosomal dominant non-syndromic hearing loss

    PubMed Central

    TAN, MINXING; SHEN, XIAOFEI; YAO, JUN; WEI, QINJUN; LU, YAJIE; CAO, XIN; XING, GUANGQIAN

    2014-01-01

    Hearing loss is the most common sensory deficit in humans and gaining a better understanding of the underlying causes is necessary to improve counseling and rehabilitation. In the present study, a genetic analysis of a Chinese family with autosomal dominant non-syndromic progressive hearing impairment was conducted and assessed. Whole-exome sequencing in combination with a co-segregation analysis identified a novel missense mutation in EYA4 exon 15 (c.T1301A; p.I411K). The mutation segregated with the hearing loss of the family. This mutation was not identified in the databases of 1000 Genome Project, dbSNP 130, HapMap and YH project or in matched controls. Bioinformatic analysis confirmed the pathogenic effects of this mutation. To the best of our knowledge, this is the first report to provide a description of a missense mutation in the EYA4 gene resulting in non-syndromic hearing loss. Our results provide additional molecular and clinical information in order to gain improved understanding of the pathogenesis of EYA4 mutations and the genotype-phenotype correlations of DFNA10 hearing loss. PMID:25242383

  17. Identification of I411K, a novel missense EYA4 mutation causing autosomal dominant non‑syndromic hearing loss.

    PubMed

    Tan, Minxing; Shen, Xiaofei; Yao, Jun; Wei, Qinjun; Lu, Yajie; Cao, Xin; Xing, Guangqian

    2014-12-01

    Hearing loss is the most common sensory deficit in humans and gaining a better understanding of the underlying causes is necessary to improve counseling and rehabilitation. In the present study, a genetic analysis of a Chinese family with autosomal dominant non‑syndromic progressive hearing impairment was conducted and assessed. Whole‑exome sequencing in combination with a co‑segregation analysis identified a novel missense mutation in EYA4 exon 15 (c.T1301A; p.I411K). The mutation segregated with the hearing loss of the family. This mutation was not identified in the databases of 1000 genome Project, dbSNP 130, HapMap and YH project or in matched controls. Bioinformatic analysis confirmed the pathogenic effects of this mutation. To the best of our knowledge, this is the first report to provide a description of a missense mutation in the EYA4 gene resulting in non‑syndromic hearing loss. Our results provide additional molecular and clinical information in order to gain improved understanding of the pathogenesis of EYA4 mutations and the genotype‑phenotype correlations of DFNA10 hearing loss. PMID:25242383

  18. In Silico and In Vitro Investigations of the Mutability of Disease-Causing Missense Mutation Sites in Spermine Synthase

    PubMed Central

    Zhang, Zhe; Norris, Joy; Schwartz, Charles; Alexov, Emil

    2011-01-01

    Background Spermine synthase (SMS) is a key enzyme controlling the concentration of spermidine and spermine in the cell. The importance of SMS is manifested by the fact that single missense mutations were found to cause Snyder-Robinson Syndrome (SRS). At the same time, currently there are no non-synonymous single nucleoside polymorphisms, nsSNPs (harmless mutations), found in SMS, which may imply that the SMS does not tolerate amino acid substitutions, i.e. is not mutable. Methodology/Principal Findings To investigate the mutability of the SMS, we carried out in silico analysis and in vitro experiments of the effects of amino acid substitutions at the missense mutation sites (G56, V132 and I150) that have been shown to cause SRS. Our investigation showed that the mutation sites have different degree of mutability depending on their structural micro-environment and involvement in the function and structural integrity of the SMS. It was found that the I150 site does not tolerate any mutation, while V132, despite its key position at the interface of SMS dimer, is quite mutable. The G56 site is in the middle of the spectra, but still quite sensitive to charge residue replacement. Conclusions/Significance The performed analysis showed that mutability depends on the detail of the structural and functional factors and cannot be predicted based on conservation of wild type properties alone. Also, harmless nsSNPs can be expected to occur even at sites at which missense mutations were found to cause diseases. PMID:21647366

  19. A missense mutation in the ZFHX1B gene associated with an atypical Mowat-Wilson syndrome phenotype.

    PubMed

    Heinritz, Wolfram; Zweier, Christiane; Froster, Ursula G; Strenge, Sibylle; Kujat, Annegret; Syrbe, Steffen; Rauch, Anita; Schuster, Volker

    2006-06-01

    Mowat-Wilson syndrome (MWS) is a rare mental retardation-multiple congenital anomalies syndrome associated with typical facial dysmorphism. Patients can show a variety of other anomalies like short stature, microcephaly, Hirschsprung disease, malformations of the brain, seizures, congenital heart defects and urogenital anomalies. Mutations leading to haploinsufficiency of the ZFHX1B gene have been described as the underlying cause of this condition. We report on the clinical findings in a 2(1/2)-year-old boy with some aspects out of the MWS-spectrum in addition to unusual anomalies and a novel missense mutation in the ZFHX1B gene. PMID:16688751

  20. Brugada syndrome with a novel missense mutation in SCN5A gene: A case report from Bangladesh

    PubMed Central

    Sayeed, Md. Zahidus; Salam, Md. Abdus; Haque, Md. Zahirul; Islam, A.K.M. Monwarul

    2014-01-01

    Brugada syndrome is an inherited cardiac arrhythmia that follows autosomal dominant transmission and can cause sudden death. We report a case of Brugada syndrome in a 55-year-old male patient presented with recurrent palpitation, atypical chest pain and presyncope. ECG changes were consistent with type 1 Brugada. Gene analysis revealed a novel missense mutation in SCN5A gene with a genetic variation of D785N and a nucleotide change at 2353G-A. One of his children also had the same mutation. To our knowledge this is the first genetically proved case of Brugada syndrome in Bangladesh. PMID:24581105

  1. Exome sequencing reveals a novel missense mutation in the KIAA0196 gene in a Japanese patient with SPG8.

    PubMed

    Ichinose, Yuta; Koh, Kishin; Fukumoto, Megumi; Yamashiro, Nobuo; Kobayashi, Fumikazu; Miwa, Michiaki; Nagasaka, Takamura; Shindo, Kazumasa; Ishiura, Hiroyuki; Tsuji, Shoji; Takiyama, Dr Yoshihisa

    2016-05-01

    Exome sequencing revealed a novel missense mutation (c.2152G>A, p.E713K) in the KIAA0196 gene in a Japanese patient with SPG8. To date, only 10 mutations in the KIAA0196 gene have been reported in the world. We describe the clinical and genetic findings in our patient with SPG8, which is a rare dominant hereditary spastic paraplegia. Notably, our patient showed mild upper limb ataxia, which is a relatively atypical symptom of SPG8. Thus, our patient showed a wide clinical spectrum of SPG8. PMID:26967522

  2. Osteogenesis Imperfecta Missense Mutations in Collagen: Structural consequences of a glycine to alanine replacement at a highly charged site

    PubMed Central

    Xiao, Jianxi; Cheng, Haiming; Silva, Teresita; Baum, Jean; Brodsky, Barbara

    2011-01-01

    Glycine is required as every third residue in the collagen triple-helix, and a missense mutation leading to the replacement of even one Gly in the repeating (Gly-Xaa-Yaa)n sequence by a larger residue leads to a pathological condition. Gly to Ala missense mutations are highly underrepresented in osteogenesis imperfecta (OI) and other collagen diseases, suggesting that the smallest replacement residue Ala might cause the least structural perturbation and mildest clinical consequences. The relatively small number of Gly to Ala mutation sites that do lead to OI must have some unusual features, such as greater structural disruption due to local sequence environment or location at a biologically important site. Here, peptides are used to model a severe OI case where a Gly to Ala mutation is found within a highly stabilizing Lys-Gly-Asp sequence environment. NMR, CD and DSC studies indicate this Gly to Ala replacement leads to a substantial loss in triple-helix stability and non-equivalence of the Ala residues in the three chains such that only one of the three Ala residues is capable of form a good backbone hydrogen bond. Examination of reported OI Gly to Ala mutations suggests preferential location at known collagen binding sites, and we propose that structural defects due to Ala replacements may lead to pathology when interfering with interactions. PMID:22054507

  3. Understanding missense mutations in the BRCA1 gene: An evolutionary approach

    PubMed Central

    Fleming, Melissa A.; Potter, John D.; Ramirez, Christina J.; Ostrander, Gary K.; Ostrander, Elaine A.

    2003-01-01

    The role of missense changes in BRCA1 in breast cancer susceptibility has been difficult to establish. We used comparative evolutionary methods to identify potential functionally important amino acid sites in exon 11 and missense changes likely to disrupt gene function, aligning sequences from 57 eutherian mammals and categorizing amino acid sites by degree of conservation. We used Bayesian phylogenetic analyses to determine relationships among orthologs and identify codons evolving under positive selection. Most conserved residues occur in a region with the highest concentration of protein-interacting domains. Rapidly evolving residues are concentrated in the RAD51-interacting domain, suggesting that selection is acting most strongly on the role of BRCA1 in DNA repair. Investigation of the functional role of missense changes in breast-cancer susceptibility should focus on 38 missense changes in conserved and 3 in rapidly evolving regions of exon 11. PMID:12531920

  4. Novel WT1 Missense Mutations in Han Chinese Women with Premature Ovarian Failure.

    PubMed

    Wang, Huidan; Li, Guangyu; Zhang, Jun; Gao, Fei; Li, Weiping; Qin, Yingying; Chen, Zi-Jiang

    2015-01-01

    Premature ovarian failure (POF) is a heterogeneous disease. Though dozens of candidate genes have been identified for the genetic etiology of POF, it is largely unexplained in majority of patients. Recently, Wt1(+/R394W) mice was found to present POF-like phenotype, which indicates that WT1 might be a plausible candidate gene for non-syndromic POF. The coding region of WT1 gene was screened in 384 patients with POF and 6 novel variations were identified, including two missense mutations (p. Pro126Ser in exon1 and p. Arg370His in exon7) and four intronic variants (c.647-27C > T, c.647-13G > C, c.647-13G > A in intron1 and c.950 + 14T > C in intron 4). In vitro experiments showed that both mutant p. Pro126Ser and p. Arg370His repressed the expression of Amh and Cdh1, and induced the expression of Fshr and Cyp19 in mRNA level (P < 0.05). The expression changes of AMH, FSHR, CYP19 and CDH1 were confirmed by western blot. These genes (AMH, FSHR, CYP19 and CDH1) are required for granular cells (GCs) proliferation, differentiation and oocyte-GCs interaction. The novel mutant p. P126S and p. R370H in the WT1 gene potentially impaired GCs differentiation and oocyte-GCs interaction, which might result in loss of follicles prematurely. Therefore, WT1 is a plausible causal gene for POF. PMID:26358501

  5. Novel WT1 Missense Mutations in Han Chinese Women with Premature Ovarian Failure

    PubMed Central

    Wang, Huidan; Li, Guangyu; Zhang, Jun; Gao, Fei; Li, Weiping; Qin, Yingying; Chen, Zi-Jiang

    2015-01-01

    Premature ovarian failure (POF) is a heterogeneous disease. Though dozens of candidate genes have been identified for the genetic etiology of POF, it is largely unexplained in majority of patients. Recently, Wt1+/R394W mice was found to present POF-like phenotype, which indicates that WT1 might be a plausible candidate gene for non-syndromic POF. The coding region of WT1 gene was screened in 384 patients with POF and 6 novel variations were identified, including two missense mutations (p. Pro126Ser in exon1 and p. Arg370His in exon7) and four intronic variants (c.647-27C > T, c.647-13G > C, c.647-13G > A in intron1 and c.950 + 14T > C in intron 4). In vitro experiments showed that both mutant p. Pro126Ser and p. Arg370His repressed the expression of Amh and Cdh1, and induced the expression of Fshr and Cyp19 in mRNA level (P < 0.05). The expression changes of AMH, FSHR, CYP19 and CDH1 were confirmed by western blot. These genes (AMH, FSHR, CYP19 and CDH1) are required for granular cells (GCs) proliferation, differentiation and oocyte-GCs interaction. The novel mutant p. P126S and p. R370H in the WT1 gene potentially impaired GCs differentiation and oocyte-GCs interaction, which might result in loss of follicles prematurely. Therefore, WT1 is a plausible causal gene for POF. PMID:26358501

  6. Increased Missense Mutation Burden of Fatty Acid Metabolism Related Genes in Nunavik Inuit Population

    PubMed Central

    Zhou, Sirui; Xiong, Lan; Xie, Pingxing; Ambalavanan, Amirthagowri; Bourassa, Cynthia V.; Dionne-Laporte, Alexandre; Spiegelman, Dan; Turcotte Gauthier, Maude; Henrion, Edouard; Diallo, Ousmane; Dion, Patrick A.; Rouleau, Guy A.

    2015-01-01

    Background Nunavik Inuit (northern Quebec, Canada) reside along the arctic coastline where for generations their daily energy intake has mainly been derived from animal fat. Given this particular diet it has been hypothesized that natural selection would lead to population specific allele frequency differences and unique variants in genes related to fatty acid metabolism. A group of genes, namely CPT1A, CPT1B, CPT1C, CPT2, CRAT and CROT, encode for three carnitine acyltransferases that are important for the oxidation of fatty acids, a critical step in their metabolism. Methods Exome sequencing and SNP array genotyping were used to examine the genetic variations in the six genes encoding for the carnitine acyltransferases in 113 Nunavik Inuit individuals. Results Altogether ten missense variants were found in genes CPT1A, CPT1B, CPT1C, CPT2 and CRAT, including three novel variants and one Inuit specific variant CPT1A p.P479L (rs80356779). The latter has the highest frequency (0.955) compared to other Inuit populations. We found that by comparison to Asians or Europeans, the Nunavik Inuit have an increased mutation burden in CPT1A, CPT2 and CRAT; there is also a high level of population differentiation based on carnitine acyltransferase gene variations between Nunavik Inuit and Asians. Conclusion The increased number and frequency of deleterious variants in these fatty acid metabolism genes in Nunavik Inuit may be the result of genetic adaptation to their diet and/or the extremely cold climate. In addition, the identification of these variants may help to understand some of the specific health risks of Nunavik Inuit. PMID:26010953

  7. Parkinson-causing α-synuclein missense mutations shift native tetramers to monomers as a mechanism for disease initiation

    PubMed Central

    Dettmer, Ulf; Newman, Andrew J.; Soldner, Frank; Luth, Eric S.; Kim, Nora C.; von Saucken, Victoria E.; Sanderson, John B.; Jaenisch, Rudolf; Bartels, Tim; Selkoe, Dennis

    2015-01-01

    β-Sheet-rich α-synuclein (αS) aggregates characterize Parkinson's disease (PD). αS was long believed to be a natively unfolded monomer, but recent work suggests it also occurs in α-helix-rich tetramers. Crosslinking traps principally tetrameric αS in intact normal neurons, but not after cell lysis, suggesting a dynamic equilibrium. Here we show that freshly biopsied normal human brain contains abundant αS tetramers. The PD-causing mutation A53T decreases tetramers in mouse brain. Neurons derived from an A53T patient have decreased tetramers. Neurons expressing E46K do also, and adding 1-2 E46K-like mutations into the canonical αS repeat motifs (KTKEGV) further reduces tetramers, decreases αS solubility and induces neurotoxicity and round inclusions. The other three fPD missense mutations likewise decrease tetramer:monomer ratios. The destabilization of physiological tetramers by PD-causing missense mutations and the neurotoxicity and inclusions induced by markedly decreasing tetramers suggest that decreased α-helical tetramers and increased unfolded monomers initiate pathogenesis. Tetramer-stabilizing compounds should prevent this. PMID:26076669

  8. Congenital immunodeficiency in an individual with Wiedemann-Steiner syndrome due to a novel missense mutation in KMT2A.

    PubMed

    Stellacci, Emilia; Onesimo, Roberta; Bruselles, Alessandro; Pizzi, Simone; Battaglia, Domenica; Leoni, Chiara; Zampino, Giuseppe; Tartaglia, Marco

    2016-09-01

    Wiedemann-Steiner Syndrome (WSS) is an autosomal dominant disorder characterized by hypertrichosis, short stature, intellectual disability, developmental delay, and facial dysmorphism. Since the original reports by Wiedemann and co-workers, and Steiner and Marques, only a few cases have been described. Recently, the clinical variability of the disorder has more precisely been characterized by Jones and co-workers, who also identified heterozygous KMT2A mutations as the molecular defect underlying this condition. Here, we report on a boy with a complex phenotype overlapping WSS but exhibiting epilepsy, feeding difficulties, microcephaly, and congenital immunodeficiency with low levels of immunoglobulins as additional features. Whole exome sequencing allowed identifying a previously unreported de novo KMT2A missense mutation affecting the DNA binding domain of the methyltransferase. This finding expands the clinical phenotype associated with KMT2A mutations to include immunodeficiency and epilepsy as clinically relevant features for this disorder. © 2016 Wiley Periodicals, Inc. PMID:27320412

  9. CRIPT exonic deletion and a novel missense mutation in a female with short stature, dysmorphic features, microcephaly, and pigmentary abnormalities.

    PubMed

    Leduc, Magalie S; Niu, Zhiyv; Bi, Weimin; Zhu, Wenmiao; Miloslavskaya, Irene; Chiang, Theodore; Streff, Haley; Seavitt, John R; Murray, Stephen A; Eng, Christine; Chan, Audrey; Yang, Yaping; Lalani, Seema R

    2016-08-01

    Mutations in CRIPT encoding cysteine-rich PDZ domain-binding protein are rare, and to date have been reported in only two patients with autosomal recessive primordial dwarfism and distinctive facies. Here, we describe a female with biallelic mutations in CRIPT presenting with postnatal growth retardation, global developmental delay, and dysmorphic features including frontal bossing, high forehead, and sparse hair and eyebrows. Additional clinical features included high myopia, admixed hyper- and hypopigmented macules primarily on the face, arms, and legs, and syndactyly of 4-5 toes bilaterally. Using whole exome sequencing (WES) and chromosomal microarray analysis (CMA), we detected a c.8G>A (p.C3Y) missense variant in exon 1 of the CRIPT gene inherited from the mother and a 1,331 bp deletion encompassing exon 1, inherited from the father. The c.8G>A (p.C3Y) missense variant in CRIPT was apparently homozygous in the proband due to the exon 1 deletion. Our findings illustrate the clinical utility of combining WES with copy number variant (CNV) analysis to provide a molecular diagnosis to patients with rare Mendelian disorders. Our findings also illustrate the clinical spectrum of CRIPT related mutations. © 2016 Wiley Periodicals, Inc. PMID:27250922

  10. A novel SMARCAL1 missense mutation that affects splicing in a severely affected Schimke immunoosseous dysplasia patient.

    PubMed

    Barraza-García, Jimena; Rivera-Pedroza, Carlos I; Belinchón, Alberta; Fernández-Camblor, Carlota; Valenciano-Fuente, Blanca; Lapunzina, Pablo; Heath, Karen E

    2016-08-01

    Schimke immunoosseous dysplasia (SIOD) is an autosomal recessive disease characterized by skeletal dysplasia, focal segmental glomerulosclerosis, renal failure and immunodeficiency. In this work, we report the molecular studies undertaken in a severely affected SIOD patient that died at six years old due to nephropathy. The patient was screened for mutations using a targeted skeletal dysplasias panel. A homozygous novel missense mutation was identified, c.1615C > G (p.[Leu539Val]) that was predicted as mildly pathogenic by in silico pathogenicity prediction tools. However, splicing prediction software suggested that this variant may create a new splicing donor site in exon 9, which was subsequently confirmed using a minigene assay in HEK293 cells. Thus, the splicing alteration, c.1615C > G; r.1615c > g, 1615_1644del; (p.[Leu539_Ile548del]), results in the loss of 10 amino acids of the HARP-ATPase catalytic domain and the RPA-binding domain. Several studies have demonstrated a weak genotype-phenotype correlation among such patients. Thus, the molecular characterization has helped us to understand why a predicted weakly pathogenic missense mutation results in severe SIOD and should be considered in similar scenarios. PMID:27282802

  11. Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation

    PubMed Central

    Bose, Baundauna; Reed, Sydney E.; Besprozvannaya, Marina; Burton, Briana M.

    2016-01-01

    SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain) is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo. PMID:26849443

  12. Missense Mutations Allow a Sequence-Blind Mutant of SpoIIIE to Successfully Translocate Chromosomes during Sporulation.

    PubMed

    Bose, Baundauna; Reed, Sydney E; Besprozvannaya, Marina; Burton, Briana M

    2016-01-01

    SpoIIIE directionally pumps DNA across membranes during Bacillus subtilis sporulation and vegetative growth. The sequence-reading domain (γ domain) is required for directional DNA transport, and its deletion severely impairs sporulation. We selected suppressors of the spoIIIEΔγ sporulation defect. Unexpectedly, many suppressors were intragenic missense mutants, and some restore sporulation to near-wild-type levels. The mutant proteins are likely not more abundant, faster at translocating DNA, or sequence-sensitive, and rescue does not involve the SpoIIIE homolog SftA. Some mutants behave differently when co-expressed with spoIIIEΔγ, consistent with the idea that some, but not all, variants may form mixed oligomers. In full-length spoIIIE, these mutations do not affect sporulation, and yet the corresponding residues are rarely found in other SpoIIIE/FtsK family members. The suppressors do not rescue chromosome translocation defects during vegetative growth, indicating that the role of the γ domain cannot be fully replaced by these mutations. We present two models consistent with our findings: that the suppressors commit to transport in one arbitrarily-determined direction or delay spore development. It is surprising that missense mutations somehow rescue loss of an entire domain with a complex function, and this raises new questions about the mechanism by which SpoIIIE pumps DNA and the roles SpoIIIE plays in vivo. PMID:26849443

  13. [Resistance to acenocoumarol revealing a missense mutation of the vitamin K epoxyde reductase VKORC1: a case report].

    PubMed

    Mboup, M C; Dia, K; Ba, D M; Fall, P D

    2015-02-01

    A significant proportion of the interindividual variability of the response to vitamin K antagonist (VKA) treatment has been associated with genetic factors. Genetic variations affecting the vitamin K epoxide reductase complex subunit 1 (VKORC1) are associated with hypersensitivity or rarely with resistance to VKA. We report the case of a black women patient who presents a resistance to acenocoumarol. Despite the use of high doses of acenocoumarol (114 mg/week) for the treatment of recurrent pulmonary embolism, the International Normalized Ratio was below the therapeutic target. This resistance to acenocoumarol was confirmed by the identification of a missense mutation Val66Met of the vitamin K epoxide reductase. PMID:24095214

  14. Novel missense mutations in a conserved loop between ERCC6 (CSB) helicase motifs V and VI: Insights into Cockayne syndrome.

    PubMed

    Wilson, Brian T; Lochan, Anneline; Stark, Zornitza; Sutton, Ruth E

    2016-03-01

    Cockayne syndrome is caused by biallelic ERCC8 (CSA) or ERCC6 (CSB) mutations and is characterized by growth restriction, microcephaly, developmental delay, and premature pathological aging. Typically affected patients also have dermal photosensitivity. Although Cockayne syndrome is considered a DNA repair disorder, patients with UV-sensitive syndrome, with ERCC8 (CSA) or ERCC6 (CSB) mutations have indistinguishable DNA repair defects, but none of the extradermal features of Cockayne syndrome. We report novel missense mutations affecting a conserved loop in the ERCC6 (CSB) protein, associated with the Cockayne syndrome phenotype. Indeed, the amino acid sequence of this loop is more highly conserved than the adjacent helicase motifs V and VI, suggesting that this is a crucial structural component of the SWI/SNF family of proteins, to which ERCC6 (CSB) belongs. These comprise two RecA-like domains, separated by an interdomain linker, which interact through helicase motif VI. As the observed mutations are likely to act through destabilizing the tertiary protein structure, this prompted us to re-evaluate ERCC6 (CSB) mutation data in relation to the structure of SWI/SNF proteins. Our analysis suggests that antimorphic mutations cause Cockayne syndrome and that biallelic interdomain linker deletions produce more severe phenotypes. Based on our observations, we propose that further investigation of the pathogenic mechanisms underlying Cockayne syndrome should focus on the effect of antimorphic rather than null ERCC6 (CSB) mutations. PMID:26749132

  15. Identification of two missense mutations of ERCC6 in three Chinese sisters with Cockayne syndrome by whole exome sequencing.

    PubMed

    Yu, Shanshan; Chen, Liyuan; Ye, Lili; Fei, Lingna; Tang, Wei; Tian, Yujiao; Geng, Qian; Yi, Xin; Xie, Jiansheng

    2014-01-01

    Cockayne syndrome (CS) is a rare autosomal recessive disorder, the primary manifestations of which are poor growth and neurologic abnormality. Mutations of the ERCC6 and ERCC8 genes are the predominant cause of Cockayne syndrome, and the ERCC6 gene mutation is present in approximately 65% of cases. The present report describes a case of Cockayne syndrome in a Chinese family, with the patients carrying two missense mutations (c.1595A>G, p.Asp532Gly and c.1607T>G, p.Leu536Trp) in the ERCC6 gene in an apparently compound heterozygote status, especially, p.Asp532Gly has never been reported. The compound heterozygote mutation was found in three patients in the family using whole exome sequencing. The patients' father and mother carried a heterozygous allele at different locations of the ERCC6 gene, which was confirmed by Sanger DNA sequencing. The two mutations are both located in the highly conserved motif I of ATP-binding helicase and are considered "Damaging," "Probably Damaging," "Disease Causing," and "Conserved", indicating the role of DNA damage in the pathogenetic process of the disease. The results not only enrich the ERCC6 mutations database, but also indicate that whole exome sequencing will be a powerful tool for discovering the disease causing mutations in clinical diagnosis. PMID:25463447

  16. Molecular evolution of the tissue-nonspecific alkaline phosphatase allows prediction and validation of missense mutations responsible for hypophosphatasia.

    PubMed

    Silvent, Jérémie; Gasse, Barbara; Mornet, Etienne; Sire, Jean-Yves

    2014-08-29

    ALPL encodes the tissue nonspecific alkaline phosphatase (TNSALP), which removes phosphate groups from various substrates. Its function is essential for bone and tooth mineralization. In humans, ALPL mutations lead to hypophosphatasia, a genetic disorder characterized by defective bone and/or tooth mineralization. To date, 275 ALPL mutations have been reported to cause hypophosphatasia, of which 204 were simple missense mutations. Molecular evolutionary analysis has proved to be an efficient method to highlight residues important for the protein function and to predict or validate sensitive positions for genetic disease. Here we analyzed 58 mammalian TNSALP to identify amino acids unchanged, or only substituted by residues sharing similar properties, through 220 millions years of mammalian evolution. We found 469 sensitive positions of the 524 residues of human TNSALP, which indicates a highly constrained protein. Any substitution occurring at one of these positions is predicted to lead to hypophosphatasia. We tested the 204 missense mutations resulting in hypophosphatasia against our predictive chart, and validated 99% of them. Most sensitive positions were located in functionally important regions of TNSALP (active site, homodimeric interface, crown domain, calcium site, …). However, some important positions are located in regions, the structure and/or biological function of which are still unknown. Our chart of sensitive positions in human TNSALP (i) enables to validate or invalidate at low cost any ALPL mutation, which would be suspected to be responsible for hypophosphatasia, by contrast with time consuming and expensive functional tests, and (ii) displays higher predictive power than in silico models of prediction. PMID:25023282

  17. Molecular Evolution of the Tissue-nonspecific Alkaline Phosphatase Allows Prediction and Validation of Missense Mutations Responsible for Hypophosphatasia*

    PubMed Central

    Silvent, Jérémie; Gasse, Barbara; Mornet, Etienne; Sire, Jean-Yves

    2014-01-01

    ALPL encodes the tissue nonspecific alkaline phosphatase (TNSALP), which removes phosphate groups from various substrates. Its function is essential for bone and tooth mineralization. In humans, ALPL mutations lead to hypophosphatasia, a genetic disorder characterized by defective bone and/or tooth mineralization. To date, 275 ALPL mutations have been reported to cause hypophosphatasia, of which 204 were simple missense mutations. Molecular evolutionary analysis has proved to be an efficient method to highlight residues important for the protein function and to predict or validate sensitive positions for genetic disease. Here we analyzed 58 mammalian TNSALP to identify amino acids unchanged, or only substituted by residues sharing similar properties, through 220 millions years of mammalian evolution. We found 469 sensitive positions of the 524 residues of human TNSALP, which indicates a highly constrained protein. Any substitution occurring at one of these positions is predicted to lead to hypophosphatasia. We tested the 204 missense mutations resulting in hypophosphatasia against our predictive chart, and validated 99% of them. Most sensitive positions were located in functionally important regions of TNSALP (active site, homodimeric interface, crown domain, calcium site, …). However, some important positions are located in regions, the structure and/or biological function of which are still unknown. Our chart of sensitive positions in human TNSALP (i) enables to validate or invalidate at low cost any ALPL mutation, which would be suspected to be responsible for hypophosphatasia, by contrast with time consuming and expensive functional tests, and (ii) displays higher predictive power than in silico models of prediction. PMID:25023282

  18. Novel X-linked glomerulopathy associated with a COL4A5 missense mutation in a noncollagenous interruption

    PubMed Central

    Becknell, Brian; Zender, Gloria; Houston, Ronald; Baker, Peter; McBride, Kim L.; Luo, Wentian; Hains, David; Borza, Dorin-Bogdan; Schwaderer, Andrew L.

    2011-01-01

    We report a novel COL4A5 mutation causing rapid progression to end stage renal disease in males despite the absence of clinical and biopsy findings associated with Alport syndrome. Affected males had proteinuria, variable hematuria, early progression to end stage renal disease; and renal biopsy findings which included global and segmental glomerulosclerosis, mesangial hypercellularity and basement membrane immune complex deposition. Exon sequencing of the COL4A5 locus identified a thymine to guanine transversion at nucleotide 665, resulting in a phenylalanine to cysteine missense mutation at codon 222. This mutation was confirmed in 4 affected males and 4 female obligate carriers, but was absent in 6 asymptomatic male family members and 198 unrelated individuals. α5(IV) collagen staining in renal biopsies from affected males was normal. The phenylalanine at position 222 is 100% conserved among vertebrates. This is the first description of a mutation in a non-collagenous interruption associated with severe renal disease, providing evidence for the importance of this structural motif. The range of phenotypes associated with COL4A5 mutations is more diverse than previously realized. COL4A5 mutation analysis should be considered when glomerulonephritis presents in an X-linked inheritance pattern, even with a distinct presentation from Alport syndrome. PMID:20881942

  19. Mutational and Haplotype Analyses of Families with Familial Partial Lipodystrophy (Dunnigan Variety) Reveal Recurrent Missense Mutations in the Globular C-Terminal Domain of Lamin A/C

    PubMed Central

    Speckman, Rebecca A.; Garg, Abhimanyu; Du, Fenghe; Bennett, Lynda; Veile, Rose; Arioglu, Elif; Taylor, Simeon I.; Lovett, Michael; Bowcock, Anne M.

    2000-01-01

    Familial partial lipodystrophy (FPLD), Dunnigan variety, is an autosomal dominant disorder characterized by marked loss of subcutaneous adipose tissue from the extremities and trunk but by excess fat deposition in the head and neck. The disease is frequently associated with profound insulin resistance, dyslipidemia, and diabetes. We have localized a gene for FPLD to chromosome 1q21-q23, and it has recently been proposed that nuclear lamin A/C is altered in FPLD, on the basis of a novel missense mutation (R482Q) in five Canadian probands. This gene had previously been shown to be altered in autosomal dominant Emery-Dreifuss muscular dystrophy (EDMD-AD) and in dilated cardiomyopathy and conduction-system disease. We examined 15 families with FPLD for mutations in lamin A/C. Five families harbored the R482Q alteration that segregated with the disease phenotype. Seven families harbored an R482W alteration, and one family harbored a G465D alteration. All these mutations lie within exon 8 of the lamin A/C gene—an exon that has also been shown to harbor different missense mutations that are responsible for EDMD-AD. Mutations could not be detected in lamin A/C in one FPLD family in which there was linkage to chromosome 1q21-q23. One family with atypical FPLD harbored an R582H alteration in exon 11 of lamin A. This exon does not comprise part of the lamin C coding region. All mutations in FPLD affect the globular C-terminal domain of the lamin A/C protein. In contrast, mutations responsible for dilated cardiomyopathy and conduction-system disease are observed in the rod domain of the protein. The FPLD mutations R482Q and R482W occurred on different haplotypes, indicating that they are likely to have arisen more than once. PMID:10739751

  20. Identification of a homozygous missense mutation in LRP2 and a hemizygous missense mutation in TSPYL2 in a family with mild intellectual disability.

    PubMed

    Vasli, Nasim; Ahmed, Iltaf; Mittal, Kirti; Ohadi, Mehrnaz; Mikhailov, Anna; Rafiq, Muhammad A; Bhatti, Attya; Carter, Melissa T; Andrade, Danielle M; Ayub, Muhammad; Vincent, John B; John, Peter

    2016-04-01

    Non-syndromic autosomal recessive intellectual disability (ID) is a genetically heterogeneous disorder with more than 50 mutated genes to date. ID is characterized by deficits in memory skills and language development with difficulty in learning, problem solving, and adaptive behaviors, and affects ∼1% of the population. For detection of disease-causing mutations in such a heterogeneous disorder, homozygosity mapping together with exome sequencing is a powerful approach, as almost all known genes can be assessed simultaneously in a high-throughput manner. In this study, a hemizygous c.786C>G:p.Ile262Met in the testis specific protein Y-encoded-like 2 (TSPYL2) gene and a homozygous c.11335G>A:p.Asp3779Asn in the low-density lipoprotein receptor-related protein 2 (LRP2) gene were detected after genome-wide genotyping and exome sequencing in a consanguineous Pakistani family with two boys with mild ID. Mutations in the LRP2 gene have previously been reported in patients with Donnai-Barrow and Stickler syndromes. LRP2 has also been associated with a 2q locus for autism (AUTS5). The TSPYL2 variant is not listed in any single-nucleotide polymorphism databases, and the LRP2 variant was absent in 400 ethnically matched healthy control chromosomes, and is not listed in single-nucleotide polymorphism databases as a common polymorphism. The LRP2 mutation identified here is located in one of the low-density lipoprotein-receptor class A domains, which is a cysteine-rich repeat that plays a central role in mammalian cholesterol metabolism, suggesting that alteration of cholesterol processing pathway can contribute to ID. PMID:26529358

  1. Identification of a De Novo Heterozygous Missense FLNB Mutation in Lethal Atelosteogenesis Type I by Exome Sequencing

    PubMed Central

    Jeon, Ga Won; Lee, Mi-Na; Jung, Ji Mi; Hong, Seong Yeon; Kim, Young Nam; Sin, Jong Beom

    2014-01-01

    Background Atelosteogenesis type I (AO-I) is a rare lethal skeletal dysplastic disorder characterized by severe short-limbed dwarfism and dislocated hips, knees, and elbows. AO-I is caused by mutations in the filamin B (FLNB) gene; however, several other genes can cause AO-like lethal skeletal dysplasias. Methods In order to screen all possible genes associated with AO-like lethal skeletal dysplasias simultaneously, we performed whole-exome sequencing in a female newborn having clinical features of AO-I. Results Exome sequencing identified a novel missense variant (c.517G>A; p.Ala173Thr) in exon 2 of the FLNB gene in the patient. Sanger sequencing validated this variant, and genetic analysis of the patient's parents suggested a de novo occurrence of the variant. Conclusions This study shows that exome sequencing can be a useful tool for the identification of causative mutations in lethal skeletal dysplasia patients. PMID:24624349

  2. DNA analysis of an uncommon missense mutation in a Gaucher disease patient of Jewish-Polish-Russian descent

    SciTech Connect

    Choy, F.Y.M.; Wei, C.; Applegarth, D.A.; McGillivray, B.C.

    1994-06-01

    Gaucher disease is the most frequent lysosomal lipid storage disease. It results from deficient glucocerebrosidase activity and is transmitted as an autosomal recessive trait. Three clinical forms of Gaucher disease have been described: type 1, non-neuronopathic; type 2, acute neuronopathic; and type 3, subacute neuronopathic. We have sequenced the full length cDNA of the glucocerebrosidase gene and identified an uncommon mutation in nucleotide position 1604 (genoma DNA nucleotide position 6683) from a Gaucher disease patient of Jewish-Polish-Russian descent with type 1 Gaucher disease. It is a G{yields}A transition in exon 11 that results in {sup 496}Arg{yields}{sup 496}His of glucocerebrosidase. This missense mutation is present in the heterozygous form and creates a new cleavage site for the endonuclease HphI. We have developed a simple method to detect the presence of this mutation by using HphI restriction fragment length polymorphism analysis of glucocerebrosidase genomic DNA or cDNA. The mutation in the other Gaucher allele of this patient is an A{yields}G transition at cDNA nucleotide position 1226 which creates an XhoI cleavage site after PCR mismatch amplification. The presence of this mutation was also confirmed by sequence analysis. Based on previous reports that mutation 1226 is present only in type 1 Gaucher disease and the observation that there is no neurological involvement in this patient, we conclude that our patient with the 1226/1604 genotype is diagnosed as having type 1 Gaucher disease. Since it was also postulated that mutation 1226 in the homozygous form will usually result in a good prognosis, we speculate that the orthopedic complications and the unusual presence of glomerulosclerosis in this patient may be attributable to the mutation at nucleotide 1604. This speculation will require a description of more patients with this mutation for confirmation. 32 refs., 5 figs.

  3. Detection of a novel missense mutation in the mevalonate kinase gene in one Chinese family with DSAP

    PubMed Central

    Lu, Wen-Sheng; Zheng, Xiao-Dong; Yao, Xiu-Hua; Zhang, Lan-Fang; Hu, Bai; Lu, Yao-Juan

    2014-01-01

    Disseminated superficial actinic porokeratosis (DSAP) is the most common form of porokeratosis and a severe chronic autosomal dominant cutaneous disorder with high genetic heterogeneity. Recently, the mevalonate kinase (MVK) gene has been identified as a candidate gene responsible for DSAP and multiple mutations have been reported. Here, we report identification of a novel missense mutation in the MVK gene in a Chinese family with DSAP. A 50-year-old male was diagnosed as proband of DSAP based on the clinical and histological findings, which show numerous hyperpigmented macules by physical examination and cornoid lamella by skin biopsy. Similar skin symptoms were also observed in his father, who died many years ago. We prepared genomic DNA from the proband, unaffected individuals from his family members, as well as 100 unrelated healthy controls. PCR was then conducted using the above genomic DNA as template and the MVK gene-specific primers. The PCR product was subjected to direct sequencing and the sequence was compared to that of MVK gene within the NCBI database. We detected a heterozygous C to G transition at nucleotide 643 in exon 7 of MVK gene of the proband. This will result in an amino acid change at codon 215 (P.Arg215Gly.), which is from an arginine codon (CGA) to a Glycine codon (GGA). We did not detect any mutation in the unaffected family members or the 100 unrelated healthy controls, demonstrating that this is a novel missense mutation in MVK gene and therefore, contributes to the molecular diagnosis of DSAP. PMID:24551296

  4. A novel missense mutation in ANO5/TMEM16E is causative for gnathodiaphyseal dyplasia in a large Italian pedigree

    PubMed Central

    Marconi, Caterina; Brunamonti Binello, Paolo; Badiali, Giovanni; Caci, Emanuela; Cusano, Roberto; Garibaldi, Joseph; Pippucci, Tommaso; Merlini, Alberto; Marchetti, Claudio; Rhoden, Kerry J; Galietta, Luis J V; Lalatta, Faustina; Balbi, Paolo; Seri, Marco

    2013-01-01

    Gnathodiaphyseal dysplasia (GDD) is an autosomal dominant syndrome characterized by frequent bone fractures at a young age, bowing of tubular bones and cemento-osseus lesions of the jawbones. Anoctamin 5 (ANO5) belongs to the anoctamin protein family that includes calcium-activated chloride channels. However, recent data together with our own experiments reported here add weight to the hypothesis that ANO5 may not function as calcium-activated chloride channel. By sequencing the entire ANO5 gene coding region and untranslated regions in a large Italian GDD family, we found a novel missense mutation causing the p.Thr513Ile substitution. The mutation segregates with the disease in the family and has never been described in any database as a polymorphism. To date, only two mutations on the same cysteine residue at position 356 of ANO5 amino-acid sequence have been described in GDD families. As ANO5 has also been found to be mutated in two different forms of muscular dystrophy, the finding of this third mutation in GDD adds clues to the role of ANO5 in these disorders. PMID:23047743

  5. Revealing the Effects of Missense Mutations Causing Snyder-Robinson Syndrome on the Stability and Dimerization of Spermine Synthase

    PubMed Central

    Peng, Yunhui; Norris, Joy; Schwartz, Charles; Alexov, Emil

    2016-01-01

    Missense mutations in spermine synthase (SpmSyn) protein have been shown to cause the Snyder-Robinson syndrome (SRS). Depending on the location within the structure of SpmSyn and type of amino acid substitution, different mechanisms resulting in SRS were proposed. Here we focus on naturally occurring amino acid substitutions causing SRS, which are situated away from the active center of SpmSyn and thus are not directly involved in the catalysis. Two of the mutations, M35R and P112L, are reported for the first time in this study. It is demonstrated, both experimentally and computationally, that for such mutations the major effect resulting in dysfunctional SpmSyn is the destabilization of the protein. In vitro experiments indicated either no presence or very little amount of the mutant SpmSyn in patient cells. In silico modeling predicted that all studied mutations in this work destabilize SpmSyn and some of them abolish homo-dimer formation. Since dimerization and structural stability are equally important for the wild type function of SpmSyn, it is proposed that the SRS caused by mutations occurring in the N-domain of SpmSyn is a result of dysfunctional mutant proteins being partially unfolded and degraded by the proteomic machinery of the cell or being unable to form a homo-dimer. PMID:26761001

  6. Inappropriate tall stature and renal ectopy in a male patient with X-linked congenital adrenal hypoplasia due to a novel missense mutation in the DAX-1 gene.

    PubMed

    Franzese, Adriana; Brunetti-Pierri, Nicola; Spagnuolo, Maria Immacolata; Spadaro, Raffaella; Giugliano, Michela; Mukai, Tokuo; Valerio, Giuliana

    2005-05-15

    Mutations in DAX-1 gene cause congenital adrenal hypoplasia (AHC). We present a male patient affected by X-linked adrenal hypoplasia congenita due to a novel DAX-1 missense mutation. The mutation V287G affects the C-terminal end of the DAX-1 protein which plays an important role in functioning of the receptor. In addition, our patient presented an inappropriate tall stature and renal ectopy, which have not been described in AHC so far. PMID:15800903

  7. Rescue of Enzymatic Function for Disease-associated RPE65 Proteins Containing Various Missense Mutations in Non-active Sites*

    PubMed Central

    Li, Songhua; Izumi, Tadahide; Hu, Jane; Jin, Heather H.; Siddiqui, Ahmed-Abdul A.; Jacobson, Samuel G.; Bok, Dean; Jin, Minghao

    2014-01-01

    Over 70 different missense mutations, including a dominant mutation, in RPE65 retinoid isomerase are associated with distinct forms of retinal degeneration; however, the disease mechanisms for most of these mutations have not been studied. Although some mutations have been shown to abolish enzyme activity, the molecular mechanisms leading to the loss of enzymatic function and retinal degeneration remain poorly understood. Here we show that the 26 S proteasome non-ATPase regulatory subunit 13 (PSMD13), a newly identified negative regulator of RPE65, plays a critical role in regulating pathogenicity of three mutations (L22P, T101I, and L408P) by mediating rapid degradation of mutated RPE65s via a ubiquitination- and proteasome-dependent non-lysosomal pathway. These mutant RPE65s were misfolded and formed aggregates or high molecular complexes via disulfide bonds. Interaction of PSMD13 with mutant RPE65s promoted degradation of misfolded but not properly folded mutant RPE65s. Many mutations, including L22P, T101I, and L408P, were mapped on non-active sites. Although their activities were very low, these mutant RPE65s were catalytically active and could be significantly rescued at low temperature, whereas mutant RPE65s with a distinct active site mutation could not be rescued under the same conditions. Sodium 4-phenylbutyrate and glycerol displayed a significant synergistic effect on the low temperature rescue of the mutant RPE65s by promoting proper folding, reducing aggregation, and increasing membrane association. Our results suggest that a low temperature eye mask and sodium 4-phenylbutyrate, a United States Food and Drug Administration-approved oral medicine, may provide a promising “protein repair therapy” that can enhance the efficacy of gene therapy by reducing the cytotoxic effect of misfolded mutant RPE65s. PMID:24849605

  8. The A31P missense mutation in cardiac myosin binding protein C alters protein structure but does not cause haploinsufficiency.

    PubMed

    van Dijk, Sabine J; Bezold Kooiker, Kristina; Mazzalupo, Stacy; Yang, Yuanzhang; Kostyukova, Alla S; Mustacich, Debbie J; Hoye, Elaine R; Stern, Joshua A; Kittleson, Mark D; Harris, Samantha P

    2016-07-01

    Mutations in MYBPC3, the gene encoding cardiac myosin binding protein C (cMyBP-C), are a major cause of hypertrophic cardiomyopathy (HCM). While most mutations encode premature stop codons, missense mutations causing single amino acid substitutions are also common. Here we investigated effects of a single proline for alanine substitution at amino acid 31 (A31P) in the C0 domain of cMyBP-C, which was identified as a natural cause of HCM in cats. Results using recombinant proteins showed that the mutation disrupted C0 structure, altered sensitivity to trypsin digestion, and reduced recognition by an antibody that preferentially recognizes N-terminal domains of cMyBP-C. Western blots detecting A31P cMyBP-C in myocardium of cats heterozygous for the mutation showed a reduced amount of A31P mutant protein relative to wild-type cMyBP-C, but the total amount of cMyBP-C was not different in myocardium from cats with or without the A31P mutation indicating altered rates of synthesis/degradation of A31P cMyBP-C. Also, the mutant A31P cMyBP-C was properly localized in cardiac sarcomeres. These results indicate that reduced protein expression (haploinsufficiency) cannot account for effects of the A31P cMyBP-C mutation and instead suggest that the A31P mutation causes HCM through a poison polypeptide mechanism that disrupts cMyBP-C or myocyte function. PMID:26777460

  9. An association-adjusted consensus deleterious scheme to classify homozygous Mis-sense mutations for personal genome interpretation

    PubMed Central

    2013-01-01

    Background Personal genome analysis is now being considered for evaluation of disease risk in healthy individuals, utilizing both rare and common variants. Multiple scores have been developed to predict the deleteriousness of amino acid substitutions, using information on the allele frequencies, level of evolutionary conservation, and averaged structural evidence. However, agreement among these scores is limited and they likely over-estimate the fraction of the genome that is deleterious. Method This study proposes an integrative approach to identify a subset of homozygous non-synonymous single nucleotide polymorphisms (nsSNPs). An 8-level classification scheme is constructed from the presence/absence of deleterious predictions combined with evidence of association with disease or complex traits. Detailed literature searches and structural validations are then performed for a subset of homozygous 826 mis-sense mutations in 575 proteins found in the genomes of 12 healthy adults. Results Implementation of the Association-Adjusted Consensus Deleterious Scheme (AACDS) classifies 11% of all predicted highly deleterious homozygous variants as most likely to influence disease risk. The number of such variants per genome ranges from 0 to 8 with no significant difference between African and Caucasian Americans. Detailed analysis of mutations affecting the APOE, MTMR2, THSB1, CHIA, αMyHC, and AMY2A proteins shows how the protein structure is likely to be disrupted, even though the associated phenotypes have not been documented in the corresponding individuals. Conclusions The classification system for homozygous nsSNPs provides an opportunity to systematically rank nsSNPs based on suggestive evidence from annotations and sequence-based predictions. The ranking scheme, in-depth literature searches, and structural validations of highly prioritized mis-sense mutations compliment traditional sequence-based approaches and should have particular utility for the development of

  10. Heteroallelic missense mutations of the galactosamine-6-sulfate sulfatase (GALNS) gene in a mild form of Morquio disease (MPS IVA)

    SciTech Connect

    Cole, D.E.C.; Gordon, B.A.; Rupar, C.A.

    1996-06-28

    Morquio disease (MPS IVA) is an autosomal recessive disorder caused by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS) activity. Patients commonly present in early infancy with growth failure, spondyloepiphyseal dysplasia, corneal opacification, and keratan sulfaturia, but milder forms have been described. We report on a patient who grew normally until age 5 years. Her keratan sulfaturia was not detected until adolescence, and she now has changes restricted largely to the axial skeleton. She has experienced only mildly impaired vision. At age 22, thin-layer chromatography of purified glycosaminoglycans showed some keratan sulfaturia. GALNS activity in fibroblast homogenate supernatants was 20 {plus_minus} 5% of controls (as compared to 5 {plus_minus} 3% of controls in severe MPS IVA, P <.003). Kinetic analysis of residual fibroblast GALNS activity in patient and parents revealed decreased K{sub m} and increased V{sub max} in the mother and daughter, but not in the father, compatible with compound heterozygosity. GALNS exons were amplified from patient genomic DNA and screened by SSCP. Two missense mutations, a C to T transition at position 335 (predicting R94C) and a T to G transversion at position 344 (predicting F97V), were found on sequencing an abnormally migrating exon 3 amplicon. Digestion of the amplicon with FokI and AccI restriction enzymes (specific for the R94C and F97V mutations, respectively) confirmed heterozygosity. In fibroblast transfection experiments, heterozygous R94C and F97V mutants independently expressed as severe and mile GALNS deficiency, respectively. We interpret these findings to indicate that our patient bears heteroallelic GALNS missense mutations, leading to GALNS deficiency and mild MPS IVA. Our findings expand the clinical and biochemical phenotype of MPS IVA, but full delineation of the genotype-phenotype relationship requires further study of native and transfected mutant cell lines. 30 refs., 4 figs., 3 tabs.

  11. Structural Characterization of Missense Mutations Using High Resolution Mass Spectrometry: A Case Study of the Parkinson's-Related Protein, DJ-1

    NASA Astrophysics Data System (ADS)

    Ben-Nissan, Gili; Chotiner, Almog; Tarnavsky, Mark; Sharon, Michal

    2016-04-01

    Missense mutations that lead to the expression of mutant proteins carrying single amino acid substitutions are the cause of numerous diseases. Unlike gene lesions, insertions, deletions, nonsense mutations, or modified RNA splicing, which affect the length of a polypeptide, or determine whether a polypeptide is translated at all, missense mutations exert more subtle effects on protein structure, which are often difficult to evaluate. Here, we took advantage of the spectral resolution afforded by the EMR Orbitrap platform, to generate a mass spectrometry-based approach relying on simultaneous measurements of the wild-type protein and the missense variants. This approach not only considerably shortens the analysis time due to the concurrent acquisition but, more importantly, enables direct comparisons between the wild-type protein and the variants, allowing identification of even subtle structural changes. We demonstrate our approach using the Parkinson's-associated protein, DJ-1. Together with the wild-type protein, we examined two missense mutants, DJ-1A104T and DJ-1D149A, which lead to early-onset familial Parkinson's disease. Gas-phase, thermal, and chemical stability assays indicate clear alterations in the conformational stability of the two mutants: the structural stability of DJ-1D149A is reduced, whereas that of DJ-1A104T is enhanced. Overall, we anticipate that the methodology presented here will be applicable to numerous other missense mutants, promoting the structural investigations of multiple variants of the same protein.

  12. Structural Characterization of Missense Mutations Using High Resolution Mass Spectrometry: A Case Study of the Parkinson's-Related Protein, DJ-1

    NASA Astrophysics Data System (ADS)

    Ben-Nissan, Gili; Chotiner, Almog; Tarnavsky, Mark; Sharon, Michal

    2016-06-01

    Missense mutations that lead to the expression of mutant proteins carrying single amino acid substitutions are the cause of numerous diseases. Unlike gene lesions, insertions, deletions, nonsense mutations, or modified RNA splicing, which affect the length of a polypeptide, or determine whether a polypeptide is translated at all, missense mutations exert more subtle effects on protein structure, which are often difficult to evaluate. Here, we took advantage of the spectral resolution afforded by the EMR Orbitrap platform, to generate a mass spectrometry-based approach relying on simultaneous measurements of the wild-type protein and the missense variants. This approach not only considerably shortens the analysis time due to the concurrent acquisition but, more importantly, enables direct comparisons between the wild-type protein and the variants, allowing identification of even subtle structural changes. We demonstrate our approach using the Parkinson's-associated protein, DJ-1. Together with the wild-type protein, we examined two missense mutants, DJ-1A104T and DJ-1D149A, which lead to early-onset familial Parkinson's disease. Gas-phase, thermal, and chemical stability assays indicate clear alterations in the conformational stability of the two mutants: the structural stability of DJ-1D149A is reduced, whereas that of DJ-1A104T is enhanced. Overall, we anticipate that the methodology presented here will be applicable to numerous other missense mutants, promoting the structural investigations of multiple variants of the same protein.

  13. Missense mutations at homologous positions in the fourth and fifth laminin A G-like domains of eyes shut homolog cause autosomal recessive retinitis pigmentosa

    PubMed Central

    Khan, Muhammad Imran; Collin, Rob W.J.; Arimadyo, Kentar; Micheal, Shazia; Azam, Maleeha; Qureshi, Nadeem; Faradz, Sultana M.H.; den Hollander, Anneke I.; Qamar, Raheel

    2010-01-01

    Purpose To describe two novel mutations in the eyes shut homolog (EYS) gene in two families with autosomal recessive retinitis pigmentosa (arRP) from Pakistan and Indonesia. Methods Genome-wide linkage and homozygosity mapping were performed using single nucleotide polymorphism microarray analysis in affected members of the two arRP families. Sequence analysis was performed to identify genetic changes in protein coding exons of EYS. Results In the Indonesian and Pakistani families, homozygous regions encompassing the EYS gene at 6q12 were identified, with maximum LOD scores of 1.8 and 3.6, respectively. Novel missense variants in the EYS gene (p.D2767Y and p.D3028Y) were found in the Pakistani and Indonesian families, respectively, that co-segregate with the disease phenotype. Interestingly, the missense variants are located at the same homologous position within the fourth and fifth laminin A G-like domains of EYS. Conclusions To date, mostly protein-truncating mutations have been described in EYS, while only few patients have been described with pathogenic compound heterozygous missense mutations. The mutations p.D2767Y and p.D3028Y described in this study affect highly conserved residues at homologous positions in laminin A G-like domains and support the notion that missense mutations in EYS can cause arRP. PMID:21179430

  14. Double homozygous missense mutations in DACH1 and BMP4 in a patient with bilateral cystic renal dysplasia.

    PubMed

    Schild, Raphael; Knüppel, Tanja; Konrad, Martin; Bergmann, Carsten; Trautmann, Agnes; Kemper, Markus J; Wu, Kongming; Yaklichkin, Sergey; Wang, Jing; Pestell, Richard; Müller-Wiefel, Dirk E; Schaefer, Franz; Weber, Stefanie

    2013-01-01

    Renal hypodysplasia (RHD) is characterized by small and/or disorganized kidneys following abnormal organogenesis. Mutations in several genes have been identified recently to be associated with RHD in humans, including BMP4, a member of the transforming growth factor (TGF)-β family of growth factors. DACH1 has been proposed as a candidate gene for RHD because of its involvement in the EYA-SIX-DACH network of renal developmental genes. Here, we present a patient with renal dysplasia carrying homozygous missense mutations in both BMP4 (p.N150K) and DACH1 (p.R684C). The genotype-phenotype correlation in the family hints at an oligogenic mode of inheritance of the disease in this kindred. Functional analyses of the identified DACH1 mutation in HEK293T cells demonstrated enhanced suppression of the TGF-β pathway suggesting that both mutations could act synergistically in the development of the phenotype in this patient. This finding provides a model for RHD as an oligo-/polygenic disorder and supports a role for DACH1 in the development of RHD in humans. PMID:23262432

  15. Identification of a Novel Missense FBN2 Mutation in a Chinese Family with Congenital Contractural Arachnodactyly Using Exome Sequencing.

    PubMed

    Deng, Hao; Lu, Qian; Xu, Hongbo; Deng, Xiong; Yuan, Lamei; Yang, Zhijian; Guo, Yi; Lin, Qiongfen; Xiao, Jingjing; Guan, Liping; Song, Zhi

    2016-01-01

    Congenital contractural arachnodactyly (CCA, OMIM 121050), also known as Beals-Hecht syndrome, is an autosomal dominant disorder of connective tissue. CCA is characterized by arachnodactyly, dolichostenomelia, pectus deformities, kyphoscoliosis, congenital contractures and a crumpled appearance of the helix of the ear. The aim of this study is to identify the genetic cause of a 4-generation Chinese family of Tujia ethnicity with congenital contractural arachnodactyly by exome sequencing. The clinical features of patients in this family are consistent with CCA. A novel missense mutation, c.3769T>C (p.C1257R), in the fibrillin 2 gene (FBN2) was identified responsible for the genetic cause of our family with CCA. The p.C1257R mutation occurs in the 19th calcium-binding epidermal growth factor-like (cbEGF) domain. The amino acid residue cysteine in this domain is conserved among different species. Our findings suggest that exome sequencing is a powerful tool to discover mutation(s) in CCA. Our results may also provide new insights into the cause and diagnosis of CCA, and may have implications for genetic counseling and clinical management. PMID:27196565

  16. A novel missense mutation in the L1CAM gene in a boy with L1 disease.

    PubMed

    Simonati, A; Boaretto, F; Vettori, A; Dabrilli, P; Criscuolo, L; Rizzuto, N; Mostacciuolo, M L

    2006-06-01

    A novel missense mutation of the L1CAM gene (Xq28) is described in an adult patient affected with severe mental retardation, spastic paraparesis, adducted thumbs, agenesis of corpus callosum and microcephaly (L1 disease). We detected a transition c2308G-->A in exon 18 that caused an amino acid change in codon 770. The patient's mother and two sisters were heterozygous for the same mutation. This newly described mutation predicts the substitution of an aspartate by asparagine (D770N) in the second fibronectin (Fn2) domain of the extracellular portion of the mature L1 protein. Even if amino acid substitution does not significantly change the physico-chemical properties of the Fn2 domain, it seems clear that the integrity of this domain is required to maintain the biological functions of the protein. The feature peculiar to this patient is the decelerated head growth post-natally, leading to microcephaly. Mutations of L1CAM associated with prolonged survival may hamper post-natal brain and head growth. PMID:16816908

  17. Novel missense mutation in the GALNS gene in an affected patient with severe form of mucopolysaccharidosis type IVA.

    PubMed

    Seyedhassani, Seyed Mohammad; Hashemi-Gorji, Feyzollah; Yavari, Mahdieh; Mirfakhraie, Reza

    2015-10-23

    Mucopolysaccharidosis type IVA (MPS IVA), also known as Morquio A, is an autosomal recessive disorder characterized by a deficiency of N-acetylgalactosamine-6-sulfate sulfatase (GALNS), which causes major skeletal and connective tissue abnormalities and affects multiple organ systems. In this study, one MPS IVA patient with a severe form from consanguine large Iranian family has been investigated. To find a mutation, all of the 14 exons and intron-exon junctions of GALNS gene were sequenced. Sequencing results were analyzed using bioinformatic analysis in order to predict probable pathogenic effect of the variant. One novel homozygous missense mutation in exon 5, c.542A>G (p.Y181C), was found in the proband. That was predicted as being probably pathogenic by bioinformatics analysis. Segregation and familial study confirmed this pathogenic mutation. In conclusion, we have identified the novel mutation responsible for MPS IVA in an Iranian patient to assist in the diagnosis, genetic counseling and prenatal diagnosis of the affected families. PMID:26276046

  18. Identification of a Novel Missense FBN2 Mutation in a Chinese Family with Congenital Contractural Arachnodactyly Using Exome Sequencing

    PubMed Central

    Deng, Hao; Lu, Qian; Xu, Hongbo; Deng, Xiong; Yuan, Lamei; Yang, Zhijian; Guo, Yi; Lin, Qiongfen; Xiao, Jingjing; Guan, Liping; Song, Zhi

    2016-01-01

    Congenital contractural arachnodactyly (CCA, OMIM 121050), also known as Beals-Hecht syndrome, is an autosomal dominant disorder of connective tissue. CCA is characterized by arachnodactyly, dolichostenomelia, pectus deformities, kyphoscoliosis, congenital contractures and a crumpled appearance of the helix of the ear. The aim of this study is to identify the genetic cause of a 4-generation Chinese family of Tujia ethnicity with congenital contractural arachnodactyly by exome sequencing. The clinical features of patients in this family are consistent with CCA. A novel missense mutation, c.3769T>C (p.C1257R), in the fibrillin 2 gene (FBN2) was identified responsible for the genetic cause of our family with CCA. The p.C1257R mutation occurs in the 19th calcium-binding epidermal growth factor-like (cbEGF) domain. The amino acid residue cysteine in this domain is conserved among different species. Our findings suggest that exome sequencing is a powerful tool to discover mutation(s) in CCA. Our results may also provide new insights into the cause and diagnosis of CCA, and may have implications for genetic counseling and clinical management. PMID:27196565

  19. The Contribution of Missense Mutations in Core and Rim Residues of Protein-Protein Interfaces to Human Disease.

    PubMed

    David, Alessia; Sternberg, Michael J E

    2015-08-28

    Missense mutations at protein-protein interaction sites, called interfaces, are important contributors to human disease. Interfaces are non-uniform surface areas characterized by two main regions, "core" and "rim", which differ in terms of evolutionary conservation and physicochemical properties. Moreover, within interfaces, only a small subset of residues ("hot spots") is crucial for the binding free energy of the protein-protein complex. We performed a large-scale structural analysis of human single amino acid variations (SAVs) and demonstrated that disease-causing mutations are preferentially located within the interface core, as opposed to the rim (p<0.01). In contrast, the interface rim is significantly enriched in polymorphisms, similar to the remaining non-interacting surface. Energetic hot spots tend to be enriched in disease-causing mutations compared to non-hot spots (p=0.05), regardless of their occurrence in core or rim residues. For individual amino acids, the frequency of substitution into a polymorphism or disease-causing mutation differed to other amino acids and was related to its structural location, as was the type of physicochemical change introduced by the SAV. In conclusion, this study demonstrated the different distribution and properties of disease-causing SAVs and polymorphisms within different structural regions and in relation to the energetic contribution of amino acid in protein-protein interfaces, thus highlighting the importance of a structural system biology approach for predicting the effect of SAVs. PMID:26173036

  20. De novo missense mutations in the NAA10 gene cause severe non-syndromic developmental delay in males and females

    PubMed Central

    Popp, Bernt; Støve, Svein I; Endele, Sabine; Myklebust, Line M; Hoyer, Juliane; Sticht, Heinrich; Azzarello-Burri, Silvia; Rauch, Anita; Arnesen, Thomas; Reis, André

    2015-01-01

    Recent studies revealed the power of whole-exome sequencing to identify mutations in sporadic cases with non-syndromic intellectual disability. We now identified de novo missense variants in NAA10 in two unrelated individuals, a boy and a girl, with severe global developmental delay but without any major dysmorphism by trio whole-exome sequencing. Both de novo variants were predicted to be deleterious, and we excluded other variants in this gene. This X-linked gene encodes N-alpha-acetyltransferase 10, the catalytic subunit of the NatA complex involved in multiple cellular processes. A single hypomorphic missense variant p.(Ser37Pro) was previously associated with Ogden syndrome in eight affected males from two different families. This rare disorder is characterized by a highly recognizable phenotype, global developmental delay and results in death during infancy. In an attempt to explain the discrepant phenotype, we used in vitro N-terminal acetylation assays which suggested that the severity of the phenotype correlates with the remaining catalytic activity. The variant in the Ogden syndrome patients exhibited a lower activity than the one seen in the boy with intellectual disability, while the variant in the girl was the most severe exhibiting only residual activity in the acetylation assays used. We propose that N-terminal acetyltransferase deficiency is clinically heterogeneous with the overall catalytic activity determining the phenotypic severity. PMID:25099252

  1. Ehlers-Danlos syndrome, vascular type: a novel missense mutation in the COL3A1 gene.

    PubMed

    Masuno, Mitsuo; Watanabe, Atsushi; Naing, Banyar Than; Shimada, Takashi; Fujimoto, Wataru; Ninomiya, Shinsuke; Ueda, Yasunori; Kadota, Kazushige; Kotaka, Tatsuya; Kondo, Eisei; Yamanouchi, Yasuko; Inoue, Mika; Ouchi, Kazunobu; Kuroki, Yoshikazu

    2012-12-01

    We report a 34-year-old Japanese female with the vascular type of Ehlers-Danlos syndrome. She had thin translucent skin, extensive bruising, toe joint hypermobility, left lower extremity varicose veins, and chronic wrist, knee and ankle joint pain. She also had dizziness caused by autonomic dysfunction. Magnetic resonance angiography showed tortuous vertebral and basilar arteries, mild left carotid canal bulging, and right anterior tibial artery hypoplasia. Electron microscopic examinations of a skin biopsy revealed extremely dilated rough endoplasmic reticulum in dermal fibroblasts and wide variability of individual collagen fibril diameters. A molecular analysis using a conventional total RNA method and a high-resolution melting curve analysis using genomic DNA revealed a novel missense mutation within exon 48 of the COL3A1 gene, c.3428G>A, leading to p.Gly1143Glu. PMID:23181496

  2. The spfash mouse: a missense mutation in the ornithine transcarbamylase gene also causes aberrant mRNA splicing.

    PubMed Central

    Hodges, P E; Rosenberg, L E

    1989-01-01

    Ornithine transcarbamylase (ornithine carbamoyltransferase; carbamoyl-phosphate:L-ornithine carbamoyltransferase, EC 2.1.3.3) is a mitochondrial matrix enzyme of the mammalian urea cycle. The X chromosome-linked spfash mutation in the mouse causes partial ornithine transcarbamylase deficiency and has served as a model for the human disease. We show here that the spfash mutation is a guanine to adenine transition of the last nucleotide of the fourth exon of the ornithine transcarbamylase gene. This nucleotide change produces two remarkably different effects. First, this transition causes ornithine transcarbamylase mRNA deficiency because the involved exon nucleotide plays a part in the recognition of the adjacent splice donor site. As a result of the mutation, ornithine transcarbamylase pre-mRNA is spliced inefficiently both at this site and at a cryptic splice donor site 48 bases into the adjacent intron. Second, two mutant proteins are translated from these mRNAs. From the correctly spliced mRNA, the transition results in a change of amino acid 129 from arginine to histidine. This missense substitution has no discernable effect on mitochondrial import, subunit assembly, or enzyme activity. On the other hand, the elongated mRNA resulting from mis-splicing is translated into a dysfunctional ornithine transcarbamylase subunit elongated by the insertion of 16 amino acid residues. Images PMID:2471197

  3. Cancer associated missense mutations in BAP1 catalytic domain induce amyloidogenic aggregation: A new insight in enzymatic inactivation

    PubMed Central

    Bhattacharya, Sushmita; Hanpude, Pranita; Maiti, Tushar Kanti

    2015-01-01

    BRCA1 associated protein 1 (BAP1) is a nuclear deubiquitinase that regulates tumor suppressor activity and widely involves many cellular processes ranging from cell cycle regulation to gluconeogenesis. Impairment of enzymatic activity and nuclear localization induce abnormal cell proliferation. It is considered to be an important driver gene, which undergoes frequent mutations in several cancers. However the role of mutation and oncogenic gain of function of BAP1 are poorly understood. Here, we investigated cellular localization, enzymatic activity and structural changes for four missense mutants of the catalytic domain of BAP1, which are prevalent in different types of cancer. These mutations triggered cytoplasmic/perinuclear accumulation in BAP1 deficient cells, which has been observed in proteins that undergo aggregation in cellular condition. Amyloidogenic activity of mutant BAP1 was revealed from its reactivity towards anti oligomeric antibody in HEK293T cells. We have also noted structural destabilization in the catalytic domain mutants, which eventually produced beta amyloid structure as indicated in atomic force microscopy study. The cancer associated mutants up-regulate heat shock response and activates transcription of genes normally co-repressed by BAP1. Overall, our results unambiguously demonstrate that structural destabilization and subsequent aggregation abrogate its cellular mechanism leading to adverse outcome. PMID:26680512

  4. A Y328C missense mutation in spermine synthase causes a mild form of Snyder-Robinson syndrome.

    PubMed

    Zhang, Zhe; Norris, Joy; Kalscheuer, Vera; Wood, Tim; Wang, Lin; Schwartz, Charles; Alexov, Emil; Van Esch, Hilde

    2013-09-15

    Snyder-Robinson syndrome (SRS, OMIM: 309583) is an X-linked intellectual disability (XLID) syndrome, characterized by a collection of clinical features including facial asymmetry, marfanoid habitus, hypertonia, osteoporosis and unsteady gait. It is caused by a significant decrease or loss of spermine synthase (SMS) activity. Here, we report a new missense mutation, p.Y328C (c.1084A>G), in SMS in a family with XLID. The affected males available for evaluation had mild ID, speech and global delay, an asthenic build, short stature with long fingers and mild kyphosis. The spermine/spermidine ratio in lymphoblasts was 0.53, significantly reduced compared with normal (1.87 average). Activity analysis of SMS in the index patient failed to detect any activity above background. In silico modeling demonstrated that the Y328C mutation has a significant effect on SMS stability, resulting in decreased folding free energy and larger structural fluctuations compared with those of wild-type SMS. The loss of activity was attributed to the increase in conformational dynamics in the mutant which affects the active site geometry, rather than preventing dimer formation. Taken together, the biochemical and in silico studies confirm the p.Y328C mutation in SMS is responsible for the patients having a mild form of SRS and reveal yet another molecular mechanism resulting in a non-functional SMS causing SRS. PMID:23696453

  5. Neonatal diabetes in an infant of diabetic mother: same novel INS missense mutation in the mother and her offspring.

    PubMed

    Ozturk, Mehmet Adnan; Kurtoglu, Selim; Bastug, Osman; Korkmaz, Levent; Daar, Ghaniya; Memur, Seyma; Halis, Hulya; Günes, Tamer; Hussain, Khalid; Ellard, Sian

    2014-07-01

    Neonatal diabetes is defined as an uncontrolled hyperglycemic state occurring within the first 6 months of life. It is a rare disease with an incidence of 1 to 90,000-250,000. It is usually a disease of genetic origin in which insulin gene mutations play the main role in the disease process. A baby, born to a mother who had previously been diagnosed with type 1 diabetes mellitus at 14 months of age, had a high blood sugar level within the first few hours after birth and was subsequently diagnosed as having neonatal diabetes mellitus. Baby and mother were identified as having a novel heterozygous insulin missense mutation, p.C109R. Difficulties occurred in both follow-up and feeding of the baby. Without the addition of the mother's milk, an appropriate calorie milk formula and isophane insulin were used for the baby during follow-up. Multiple mechanisms are responsible in the pathogenesis of neonatal diabetes mellitus. Insulin gene mutations are one of the factors in the development of neonatal diabetes mellitus. If a resistant hyperglycemic state persists for a long time among babies, especially in those with intrauterine growth retardation whose mothers are diabetic, the baby concerned should be followed-up carefully for the development of neonatal diabetes mellitus. PMID:24566359

  6. A Y328C missense mutation in spermine synthase causes a mild form of Snyder–Robinson syndrome

    PubMed Central

    Zhang, Zhe; Norris, Joy; Kalscheuer, Vera; Wood, Tim; Wang, Lin; Schwartz, Charles; Alexov, Emil; Van Esch, Hilde

    2013-01-01

    Snyder–Robinson syndrome (SRS, OMIM: 309583) is an X-linked intellectual disability (XLID) syndrome, characterized by a collection of clinical features including facial asymmetry, marfanoid habitus, hypertonia, osteoporosis and unsteady gait. It is caused by a significant decrease or loss of spermine synthase (SMS) activity. Here, we report a new missense mutation, p.Y328C (c.1084A>G), in SMS in a family with XLID. The affected males available for evaluation had mild ID, speech and global delay, an asthenic build, short stature with long fingers and mild kyphosis. The spermine/spermidine ratio in lymphoblasts was 0.53, significantly reduced compared with normal (1.87 average). Activity analysis of SMS in the index patient failed to detect any activity above background. In silico modeling demonstrated that the Y328C mutation has a significant effect on SMS stability, resulting in decreased folding free energy and larger structural fluctuations compared with those of wild-type SMS. The loss of activity was attributed to the increase in conformational dynamics in the mutant which affects the active site geometry, rather than preventing dimer formation. Taken together, the biochemical and in silico studies confirm the p.Y328C mutation in SMS is responsible for the patients having a mild form of SRS and reveal yet another molecular mechanism resulting in a non-functional SMS causing SRS. PMID:23696453

  7. Physical interaction between SLX4 (FANCP) and XPF (FANCQ) proteins and biological consequences of interaction-defective missense mutations.

    PubMed

    Hashimoto, Keiji; Wada, Kunio; Matsumoto, Kyomu; Moriya, Masaaki

    2015-11-01

    SLX4 (FANCP) and XPF (FANCQ) proteins interact with each other and play a vital role in the Fanconi anemia (FA) DNA repair pathway. We have identified a SLX4 region and several amino acid residues that are responsible for this interaction. The study has revealed that the global minor allele, SLX4(Y546C), is defective in this interaction and cannot complement Fancp knockout mouse cells in mitomycin C-induced cytotoxicity or chromosomal aberrations. These results highly suggest this allele, as well as SLX4(L530Q), to be pathogenic. The interacting partner XPF is involved in various DNA repair pathways, and certain XPF mutations cause progeria, Cockayne syndrome (CS), and/or FA phenotypes. Because several atypical xeroderma pigmentosum (XP) phenotype-causing XPF missense mutations are located in the SLX4-interacting region, we suspected the disruption of the interaction with SLX4 in these XPF mutants, thereby causing severer phenotypes. The immunoprecipitation assay of cell extracts revealed that those XPF mutations, except XPF(C236R), located in the SLX4-interacting region cause instability of XPF protein, which could be the reason for the FA, progeria and/or CS phenotypes. PMID:26453996

  8. Missense mutations in β-1,3-N-acetylglucosaminyltransferase 1 (B3GNT1) cause Walker–Warburg syndrome

    PubMed Central

    Buysse, Karen; Riemersma, Moniek; Powell, Gareth; van Reeuwijk, Jeroen; Chitayat, David; Roscioli, Tony; Kamsteeg, Erik-Jan; van den Elzen, Christa; van Beusekom, Ellen; Blaser, Susan; Babul-Hirji, Riyana; Halliday, William; Wright, Gavin J.; Stemple, Derek L.; Lin, Yung-Yao; Lefeber, Dirk J.; van Bokhoven, Hans

    2013-01-01

    Several known or putative glycosyltransferases are required for the synthesis of laminin-binding glycans on alpha-dystroglycan (αDG), including POMT1, POMT2, POMGnT1, LARGE, Fukutin, FKRP, ISPD and GTDC2. Mutations in these glycosyltransferase genes result in defective αDG glycosylation and reduced ligand binding by αDG causing a clinically heterogeneous group of congenital muscular dystrophies, commonly referred to as dystroglycanopathies. The most severe clinical form, Walker–Warburg syndrome (WWS), is characterized by congenital muscular dystrophy and severe neurological and ophthalmological defects. Here, we report two homozygous missense mutations in the β-1,3-N-acetylglucosaminyltransferase 1 (B3GNT1) gene in a family affected with WWS. Functional studies confirmed the pathogenicity of the mutations. First, expression of wild-type but not mutant B3GNT1 in human prostate cancer (PC3) cells led to increased levels of αDG glycosylation. Second, morpholino knockdown of the zebrafish b3gnt1 orthologue caused characteristic muscular defects and reduced αDG glycosylation. These functional studies identify an important role of B3GNT1 in the synthesis of the uncharacterized laminin-binding glycan of αDG and implicate B3GNT1 as a novel causative gene for WWS. PMID:23359570

  9. Hypogonadotropic Hypogonadism due to a Novel Missense Mutation in the First Extracellular Loop of the Neurokinin B Receptor

    PubMed Central

    Bereket, Abdullah; Rocha, Nuno; Porter, Keith; Turan, Serap; Gribble, Fiona M.; Kotan, L. Damla; Akcay, Teoman; Atay, Zeynep; Canan, Husniye; Serin, Ayse; O’Rahilly, Stephen; Reimann, Frank; Semple, Robert K.; Topaloglu, A. Kemal

    2015-01-01

    Context The neurokinin B (NKB) receptor, encoded by TACR3, is widely expressed within the central nervous system, including hypothalamic nuclei involved in regulating GnRH release. We have recently reported two mutations in transmembrane segments of the receptor and a missense mutation in NKB in patients with normosmic isolated hypogonadotropic hypogonadism (nIHH). Patients and Methods We sequenced the TACR3 gene in a family in which three siblings had nIHH. The novel mutant receptor thus identified was studied in a heterologous expression system using calcium flux as the functional readout. Results All affected siblings were homozygous for the His148Leu mutation, in the first extracellular loop of the NKB receptor. The His148Leu mutant receptor exhibited profoundly impaired signaling in response to NKB (EC50 = 3 ± 0.1 nm and >5 μm for wild-type and His148Leu, respectively). The location of the mutation in an extracellular part of the receptor led us also to test whether senktide, a synthetic NKB analog, may retain ability to stimulate the mutant receptor. However, the signaling activity of the His148Leu receptor in response to senktide was also severely impaired (EC50 = 1 ± 1 nm for wild-type and no significant response of His148Leu to 10 μm). Conclusions Homozygosity for the TACR3 His148Leu mutation leads to failure of sexual maturation in humans, whereas signaling by the mutant receptor in vitro in response to either NKB or senktide is severely impaired. These observations further strengthen the link between NKB, the NKB receptor, and regulation of human reproductive function. PMID:19755480

  10. Missense mutation in the Chlamydomonas chloroplast gene that encodes the Rubisco large subunit

    SciTech Connect

    Spreitzer, R.J.; Brown, T.; Chen, Zhixiang; Zhang, Donghong; Al-Abed, S.R. )

    1988-04-01

    The 69-12Q mutant of Chlamydomonas reinhardtii lacks ribulose-1,5-bisphosphate carboxylase activity, but retains holoenzyme protein. It results from a mutation in the chloroplast large-subunit gene that causes an isoleucine-for-threonine substitution at amino-acid residue 173. Considering that lysine-175 is involved in catalysis, it appears that mutations cluster at the active site.

  11. Identification of 31 novel mutations in the F8 gene in Spanish hemophilia A patients: structural analysis of 20 missense mutations suggests new intermolecular binding sites.

    PubMed

    Venceslá, Adoración; Corral-Rodríguez, María Angeles; Baena, Manel; Cornet, Mónica; Domènech, Montserrat; Baiget, Montserrat; Fuentes-Prior, Pablo; Tizzano, Eduardo F

    2008-04-01

    Hemophilia A (HA) is an X-linked bleeding disorder caused by a wide variety of mutations in the factor 8 (F8) gene, leading to absent or deficient factor VIII (FVIII). We analyzed the F8 gene of 267 unrelated Spanish patients with HA. After excluding patients with the common intron-1 and intron-22 inversions and large deletions, we detected 137 individuals with small mutations, 31 of which had not been reported previously. Eleven of these were nonsense, frameshift, and splicing mutations, whereas 20 were missense changes. We assessed the impact of the 20 substitutions based on currently available information about FV and FVIII structure and function relationship, including previously reported results of replacements at these and topologically equivalent positions. Although most changes are likely to cause gross structural perturbations and concomitant cofactor instability, p.Ala375Ser is predicted to affect cofactor activation. Finally, 3 further mutations (p.Pro64Arg, p.Gly494Val, and p.Asp2267Gly) appear to affect cofactor interactions with its carrier protein, von Willebrand factor, with the scavenger receptor low-density lipoprotein receptor-related protein (LRP), and/or with the substrate of the FVIIIapi*FIXa (Xase) complex, factor X. Characterization of these novel mutations is important for adequate genetic counseling in HA families, but also contributes to a better understanding of FVIII structure-function relationship. PMID:18184865

  12. Identification of 31 novel mutations in the F8 gene in Spanish hemophilia A patients: structural analysis of 20 missense mutations suggests new intermolecular binding sites

    PubMed Central

    Venceslá, Adoración; Corral-Rodríguez, María Ángeles; Baena, Manel; Cornet, Mónica; Domènech, Montserrat; Baiget, Montserrat; Fuentes-Prior, Pablo

    2008-01-01

    Hemophilia A (HA) is an X-linked bleeding disorder caused by a wide variety of mutations in the factor 8 (F8) gene, leading to absent or deficient factor VIII (FVIII). We analyzed the F8 gene of 267 unrelated Spanish patients with HA. After excluding patients with the common intron-1 and intron-22 inversions and large deletions, we detected 137 individuals with small mutations, 31 of which had not been reported previously. Eleven of these were nonsense, frameshift, and splicing mutations, whereas 20 were missense changes. We assessed the impact of the 20 substitutions based on currently available information about FV and FVIII structure and function relationship, including previously reported results of replacements at these and topologically equivalent positions. Although most changes are likely to cause gross structural perturbations and concomitant cofactor instability, p.Ala375Ser is predicted to affect cofactor activation. Finally, 3 further mutations (p.Pro64Arg, p.Gly494Val, and p.Asp2267Gly) appear to affect cofactor interactions with its carrier protein, von Willebrand factor, with the scavenger receptor low-density lipoprotein receptor–related protein (LRP), and/or with the substrate of the FVIIIapi•FIXa (Xase) complex, factor X. Characterization of these novel mutations is important for adequate genetic counseling in HA families, but also contributes to a better understanding of FVIII structure-function relationship. PMID:18184865

  13. Multisystem disorder associated with a missense mutation in the mitochondrial cytochrome b gene.

    PubMed

    Wibrand, F; Ravn, K; Schwartz, M; Rosenberg, T; Horn, N; Vissing, J

    2001-10-01

    Mitochondrial cytochrome b mutations have been reported to have a homogenous phenotype of pure exercise intolerance. We describe a novel mutation in the cytochrome b gene of mitochondrial DNA (A15579G) associated with a selective decrease of muscle complex III activity in a patient who, besides severe exercise intolerance, also has multisystem manifestations (deafness, mental retardation, retinitis pigmentosa, cataract, growth retardation, epilepsy). The point mutation is heteroplasmic in muscle (88%) and leukocytes (15%), and changes a highly conserved tyrosine to cysteine at amino acid position 278. PMID:11601507

  14. A mouse model of human congenital heart disease: high incidence of diverse cardiac anomalies and ventricular noncompaction produced by heterozygous Nkx2-5 homeodomain missense mutation

    PubMed Central

    Chang, Eileen I.; Terada, Ryota; Ryan, Nicole J.; Briggs, Laura E.; Chowdhury, Rajib; Zárate, Miguel A.; Sugi, Yukiko; Nam, Hyun-Joo; Benson, D. Woodrow; Anderson, Robert H.; Kasahara, Hideko

    2014-01-01

    Background Heterozygous human mutations of NKX2-5 are highly penetrant and associated with varied congenital heart defects. The heterozygous knockout of murine Nkx2-5, in contrast, manifests less profound cardiac malformations, with low disease penetrance. We sought to study this apparent discrepancy between human and mouse genetics. Since missense mutations in the NKX2-5 homeodomain (DNA binding domain) are the most frequently reported type of human mutation, we replicated this genetic defect in a murine knock-in model. Methods and Results We generated a murine model in a 129/Sv genetic background by knocking-in an Nkx2-5 homeodomain missense mutation previously identified in humans. The mutation was located at homeodomain position 52Arg→Gly (R52G). All the heterozygous neonatal Nkx2-5+/R52G mice demonstrated a prominent trabecular layer in the ventricular wall, so called noncompaction, along with diverse cardiac anomalies, including atrioventricular septal defects, Ebstein’s malformation of the tricuspid valve, and perimembranous and/or muscular ventricular septal defects. In addition, P10 Nkx2-5+/R52G mice demonstrated atrial septal anomalies, with significant increase in the size of the inter-atrial communication and fossa ovalis, and decrease in the length of the flap valve compared to control Nkx2-5+/+ or Nkx2-5+/− mice. Conclusion The results of our study demonstrate that heterozygous missense mutation in the murine Nkx2-5 homeodomain (R52G) are highly penetrant, and result in pleiotropic cardiac effects. Thus, in contrast to heterozygous Nkx2-5 knockout mice, the effects of the heterozygous knock-in mimic findings in humans with heterozygous missense mutation in NKX2-5 homeodomain. PMID:25028484

  15. A Novel Missense Mutation of GATA4 in a Chinese Family with Congenital Heart Disease

    PubMed Central

    Wang, Bo; Chen, Sun; Fu, Qihua; Sun, Kun

    2016-01-01

    Background Congenital heart disease (CHD) is the most prevalent type of birth defect in human, with high morbidity in infant. Several genes essential for heart development have been identified. GATA4 is a pivotal transcription factor that can regulate the cardiac development. Many GATA4 mutations have been identified in patients with different types of CHD. Aims In this study, the NKX2-5, HAND1 and GATA4 coding regions were sequenced in a family spanning three generations in which seven patients had CHD. Disease-causing potential variation in this family was evaluated by bioinformatics programs and the transcriptional activity of mutant protein was analyzed by the dual luciferase reporter assay. Results A novel GATA4 mutation, c.C931T (p.R311W), was identified and co-segregated with the affected patients in this family. The bioinformatics programs predicted this heterozygous mutation to be deleterious and the cross-species alignment of GATA4 sequences showed that the mutation occurred within a highly conserved amino acid. Even though it resided in the nuclear localization signal domain, the mutant protein didn’t alter its intracellular distribution. Nevertheless, further luciferase reporter assay demonstrated that the p.R311W mutation reduced the ability of GATA4 to activate its downstream target gene. Conclusions Our study identified a novel mutation in GATA4 that likely contributed to the CHD in this family. This finding expanded the spectrum of GATA4 mutations and underscored the pathogenic correlation between GATA4 mutations and CHD. PMID:27391137

  16. Missense Mutations in SLC26A8, Encoding a Sperm-Specific Activator of CFTR, Are Associated with Human Asthenozoospermia

    PubMed Central

    Dirami, Thassadite; Rode, Baptiste; Jollivet, Mathilde; Da Silva, Nathalie; Escalier, Denise; Gaitch, Natacha; Norez, Caroline; Tuffery, Pierre; Wolf, Jean-Philippe; Becq, Frédéric; Ray, Pierre F.; Dulioust, Emmanuel; Gacon, Gérard; Bienvenu, Thierry; Touré, Aminata

    2013-01-01

    The cystic fibrosis transmembrane conductance regulator (CFTR) is present in mature sperm and is required for sperm motility and capacitation. Both these processes are controlled by ions fluxes and are essential for fertilization. We have shown that SLC26A8, a sperm-specific member of the SLC26 family of anion exchangers, associates with the CFTR channel and strongly stimulates its activity. This suggests that the two proteins cooperate to regulate the anion fluxes required for correct sperm motility and capacitation. Here, we report on three heterozygous SLC26A8 missense mutations identified in a cohort of 146 men presenting with asthenozoospermia: c.260G>A (p.Arg87Gln), c.2434G>A (p.Glu812Lys), and c.2860C>T (p.Arg954Cys). These mutations were not present in 121 controls matched for ethnicity, and statistical analysis on a control population of 8,600 individuals (from dbSNP and 1000 Genomes) showed them to be associated with asthenozoospermia with a power > 95%. By cotransfecting Chinese hamster ovary (CHO)-K1 cells with SLC26A8 variants and CFTR, we showed that the physical interaction between the two proteins was partly conserved but that the capacity to activate CFTR-dependent anion transport was completely abolished for all mutants. Biochemical studies revealed the presence of much smaller amounts of protein for all variants, but these amounts were restored to wild-type levels upon treatment with the proteasome inhibitor MG132. Immunocytochemistry also showed the amounts of SLC26A8 in sperm to be abnormally small in individuals carrying the mutations. These mutations might therefore impair formation of the SLC26A8-CFTR complex, principally by affecting SLC26A8 stability, consistent with an impairment of CFTR-dependent sperm-activation events in affected individuals. PMID:23582645

  17. Ameliorating pathogenesis by removing an exon containing a missense mutation: a potential exon-skipping therapy for laminopathies.

    PubMed

    Scharner, J; Figeac, N; Ellis, J A; Zammit, P S

    2015-06-01

    Exon skipping, as a therapy to restore a reading frame or switch protein isoforms, is under clinical trial. We hypothesised that removing an in-frame exon containing a mutation could also improve pathogenic phenotypes. Our model is laminopathies: incurable tissue-specific degenerative diseases associated with LMNA mutations. LMNA encodes A-type lamins, that together with B-type lamins, form the nuclear lamina. Lamins contain an alpha-helical central rod domain composed of multiple heptad repeats. Eliminating LMNA exon 3 or 5 removes six heptad repeats, so shortens, but should not otherwise significantly alter, the alpha-helix. Human Lamin A or Lamin C with a deletion corresponding to amino acids encoded by exon 5 (Lamin A/C-Δ5) localised normally in murine lmna-null cells, rescuing both nuclear shape and endogenous Lamin B1/emerin distribution. However, Lamin A carrying pathogenic mutations in exon 3 or 5, or Lamin A/C-Δ3, did not. Furthermore, Lamin A/C-Δ5 was not deleterious to wild-type cells, unlike the other Lamin A mutants including Lamin A/C-Δ3. Thus Lamin A/C-Δ5 function as effectively as wild-type Lamin A/C and better than mutant versions. Antisense oligonucleotides skipped LMNA exon 5 in human cells, demonstrating the possibility of treating certain laminopathies with this approach. This proof-of-concept is the first to report the therapeutic potential of exon skipping for diseases arising from missense mutations. PMID:25832542

  18. Functional analysis of a novel missense mutation in AXIN2 associated with non-syndromic tooth agenesis.

    PubMed

    Yue, Haitang; Liang, Jia; Yang, Kai; Hua, Bo; Bian, Zhuan

    2016-06-01

    Tooth agenesis is a congenital anomaly frequently seen in humans. Several genes have been associated with non-syndromic tooth agenesis, including msh homeobox 1 (MSX1), paired box 9 (PAX9), axis inhibition protein 2 (AXIN2), ectodysplasin A (EDA), and wingless-type MMTV integration site family member 10A (WNT10A). In this study, we investigated a Chinese family with non-syndromic tooth agenesis. A novel missense mutation (c.C1978T) in AXIN2 was identified in affected members. The mutation results in a His660Tyr substitution located between the Axin beta-catenin binding domain and the DIX domain of the axis inhibition protein 2 (AXIN2). We analysed this novel AXIN2 mutant, together with two reported AXIN2 mutants [c.1966C>T (p.Arg656Stop) and c.1994delG (p.Leu688Stop)] that cause colorectal cancer with and without oligodontia, to study the effect of the mutant p.His660Tyr on the Wnt/β-catenin signaling pathway and to compare the molecular pathogenesis of different AXIN2 mutants in tooth agenesis and carcinogenesis. Further in vitro experiments indicated that the mutant p.His660Tyr caused inhibition of the Wnt/β-catenin pathway, and the mutants p.Arg656Stop and p.Leu688Stop resulted in over-activation of the Wnt/β-catenin pathway. In line with previous AXIN2 mutation studies, we suggest that AXIN2 mutations with different levels of severity may have distinct effects on the Wnt pathway and the phenotype of disease. Our study provides functional evidence supporting the notion that both inhibition and over-activation of the Wnt pathway may lead to tooth agenesis. PMID:27090353

  19. The Contribution of Missense Mutations in Core and Rim Residues of Protein–Protein Interfaces to Human Disease

    PubMed Central

    David, Alessia; Sternberg, Michael J.E.

    2015-01-01

    Missense mutations at protein–protein interaction sites, called interfaces, are important contributors to human disease. Interfaces are non-uniform surface areas characterized by two main regions, “core” and “rim”, which differ in terms of evolutionary conservation and physicochemical properties. Moreover, within interfaces, only a small subset of residues (“hot spots”) is crucial for the binding free energy of the protein–protein complex. We performed a large-scale structural analysis of human single amino acid variations (SAVs) and demonstrated that disease-causing mutations are preferentially located within the interface core, as opposed to the rim (p < 0.01). In contrast, the interface rim is significantly enriched in polymorphisms, similar to the remaining non-interacting surface. Energetic hot spots tend to be enriched in disease-causing mutations compared to non-hot spots (p = 0.05), regardless of their occurrence in core or rim residues. For individual amino acids, the frequency of substitution into a polymorphism or disease-causing mutation differed to other amino acids and was related to its structural location, as was the type of physicochemical change introduced by the SAV. In conclusion, this study demonstrated the different distribution and properties of disease-causing SAVs and polymorphisms within different structural regions and in relation to the energetic contribution of amino acid in protein–protein interfaces, thus highlighting the importance of a structural system biology approach for predicting the effect of SAVs. PMID:26173036

  20. Novel de novo EEF1A2 missense mutations causing epilepsy and intellectual disability

    PubMed Central

    Lam, Wayne W.K.; Millichap, John J.; Soares, Dinesh C.; Chin, Richard; McLellan, Ailsa; FitzPatrick, David R.; Elmslie, Frances; Lees, Melissa M.; Schaefer, G. Bradley

    2016-01-01

    Background Exome sequencing has led to the discovery of mutations in novel causative genes for epilepsy. One such gene is EEF1A2, encoding a neuromuscular specific translation elongation factor, which has been found to be mutated de novo in five cases of severe epilepsy. We now report on a further seven cases, each with a different mutation, of which five are newly described. Methods New cases were identified and sequenced through the Deciphering Developmental Disabilities project, via direct contact with neurologists or geneticists, or recruited via our website. Results All the mutations cause epilepsy and intellectual disability, but with a much wider range of severity than previously identified. All new cases share specific subtle facial dysmorphic features. Each mutation occurs at an evolutionarily highly conserved amino acid position indicating strong structural or functional selective pressure. Conclusions EEF1A2 should be considered as a causative gene not only in cases of epileptic encephalopathy but also in children with less severe epilepsy and intellectual disability. The emergence of a possible discernible phenotype, a broad nasal bridge, tented upper lip, everted lower lip and downturned corners of the mouth may help in identifying patients with mutations in EEF1A2. PMID:27441201

  1. Proxy Molecular Diagnosis from Whole-Exome Sequencing Reveals Papillon-Lefevre Syndrome Caused by a Missense Mutation in CTSC

    PubMed Central

    Erzurumluoglu, A. Mesut; Alsaadi, Muslim M.; Rodriguez, Santiago; Alotaibi, Tahani S.; Guthrie, Philip A. I.; Lewis, Sian; Ginwalla, Aasiya; Gaunt, Tom R.; Alharbi, Khalid K.; Alsaif, Fahad M.; Alsaadi, Basma M.; Day, Ian N. M.

    2015-01-01

    Papillon-Lefevre syndrome (PLS) is an autosomal recessive disorder characterised by severe early onset periodontitis and palmoplantar hyperkeratosis. A previously reported missense mutation in the CTSC gene (NM_001814.4:c.899G>A:p.(G300D)) was identified in a homozygous state in two siblings diagnosed with PLS in a consanguineous family of Arabic ancestry. The variant was initially identified in a heterozygous state in a PLS unaffected sibling whose whole exome had been sequenced as part of a previous Primary ciliary dyskinesia study. Using this information, a proxy molecular diagnosis was made on the PLS affected siblings after consent was given to study this second disorder found to be segregating within the family. The prevalence of the mutation was then assayed in the local population using a representative sample of 256 unrelated individuals. The variant was absent in all subjects indicating that the variant is rare in Saudi Arabia. This family study illustrates how whole-exome sequencing can generate findings and inferences beyond its primary goal. PMID:25799584

  2. In silico analysis of missense mutations in LPAR6 reveals abnormal phospholipid signaling pathway leading to hypotrichosis.

    PubMed

    Raza, Syed Irfan; Muhammad, Dost; Jan, Abid; Ali, Raja Hussain; Hassan, Mubashir; Ahmad, Wasim; Rashid, Sajid

    2014-01-01

    Autosomal recessive hypotrichosis is a rare genetic irreversible hair loss disorder characterized by sparse scalp hair, sparse to absent eyebrows and eyelashes, and sparse axillary and body hair. The study, presented here, established genetic linkage in four families showing similar phenotypes to lysophosphatidic acid receptor 6 (LPAR6) gene on chromosome 13q14.11-q21.32. Subsequently, sequence analysis of the gene revealed two previously reported missense mutations including p.D63V in affected members of one and p.I188F in three other families. Molecular modeling and docking analysis was performed to investigate binding of a ligand oleoyl-L-alpha-lysophosphatidic acid (LPA) to modeled protein structures of normal and mutated (D63V, G146R, I188F, N248Y, S3T, L277P) LPAR6 receptors. The mutant receptors showed a complete shift in orientation of LPA at the binding site. In addition, hydropathy analysis revealed a significant change in the membrane spanning topology of LPAR6 helical segments. The present study further substantiated involvement of LPAR6-LPA signaling in the pathogenesis of hypotrichosis/woolly hair and provided additional insight into the molecular mechanism of hair development. PMID:25119526

  3. In Silico Analysis of Missense Mutations in LPAR6 Reveals Abnormal Phospholipid Signaling Pathway Leading to Hypotrichosis

    PubMed Central

    Raza, Syed Irfan; Muhammad, Dost; Jan, Abid; Ali, Raja Hussain; Hassan, Mubashir; Ahmad, Wasim; Rashid, Sajid

    2014-01-01

    Autosomal recessive hypotrichosis is a rare genetic irreversible hair loss disorder characterized by sparse scalp hair, sparse to absent eyebrows and eyelashes, and sparse axillary and body hair. The study, presented here, established genetic linkage in four families showing similar phenotypes to lysophosphatidic acid receptor 6 (LPAR6) gene on chromosome 13q14.11-q21.32. Subsequently, sequence analysis of the gene revealed two previously reported missense mutations including p.D63V in affected members of one and p.I188F in three other families. Molecular modeling and docking analysis was performed to investigate binding of a ligand oleoyl-L-alpha-lysophosphatidic acid (LPA) to modeled protein structures of normal and mutated (D63V, G146R, I188F, N248Y, S3T, L277P) LPAR6 receptors. The mutant receptors showed a complete shift in orientation of LPA at the binding site. In addition, hydropathy analysis revealed a significant change in the membrane spanning topology of LPAR6 helical segments. The present study further substantiated involvement of LPAR6-LPA signaling in the pathogenesis of hypotrichosis/woolly hair and provided additional insight into the molecular mechanism of hair development. PMID:25119526

  4. Mucolipidosis III GNPTG Missense Mutations Cause Misfolding of the γ Subunit of GlcNAc-1-Phosphotransferase.

    PubMed

    van Meel, Eline; Kornfeld, Stuart

    2016-07-01

    The lysosomal storage disorder ML III γ is caused by defects in the γ subunit of UDP-GlcNAc:lysosomal enzyme N-acetylglucosamine-1-phosphotransferase, the enzyme that tags lysosomal enzymes with the mannose 6-phosphate lysosomal targeting signal. In patients with this disorder, most of the newly synthesized lysosomal enzymes are secreted rather than being sorted to lysosomes, resulting in increased levels of these enzymes in the plasma. Several missense mutations in GNPTG, the gene encoding the γ subunit, have been reported in mucolipidosis III γ patients. However, in most cases, the impact of these mutations on γ subunit function has remained unclear. Here, we report that the variants c.316G>A (p.G106S), c.376G>A (p.G126S), and c.425G>A (p.C142Y) cause misfolding of the γ subunit, whereas another variant, c.857C>T (p.T286M), does not appear to alter γ subunit function. The misfolded γ subunits were retained in the ER and failed to rescue the lysosomal targeting of lysosomal acid glycosidases. PMID:27038293

  5. A Missense Mutation in KCTD17 Causes Autosomal Dominant Myoclonus-Dystonia

    PubMed Central

    Mencacci, Niccolo E.; Rubio-Agusti, Ignacio; Zdebik, Anselm; Asmus, Friedrich; Ludtmann, Marthe H.R.; Ryten, Mina; Plagnol, Vincent; Hauser, Ann-Kathrin; Bandres-Ciga, Sara; Bettencourt, Conceição; Forabosco, Paola; Hughes, Deborah; Soutar, Marc M.P.; Peall, Kathryn; Morris, Huw R.; Trabzuni, Daniah; Tekman, Mehmet; Stanescu, Horia C.; Kleta, Robert; Carecchio, Miryam; Zorzi, Giovanna; Nardocci, Nardo; Garavaglia, Barbara; Lohmann, Ebba; Weissbach, Anne; Klein, Christine; Hardy, John; Pittman, Alan M.; Foltynie, Thomas; Abramov, Andrey Y.; Gasser, Thomas; Bhatia, Kailash P.; Wood, Nicholas W.

    2015-01-01

    Myoclonus-dystonia (M-D) is a rare movement disorder characterized by a combination of non-epileptic myoclonic jerks and dystonia. SGCE mutations represent a major cause for familial M-D being responsible for 30%–50% of cases. After excluding SGCE mutations, we identified through a combination of linkage analysis and whole-exome sequencing KCTD17 c.434 G>A p.(Arg145His) as the only segregating variant in a dominant British pedigree with seven subjects affected by M-D. A subsequent screening in a cohort of M-D cases without mutations in SGCE revealed the same KCTD17 variant in a German family. The clinical presentation of the KCTD17-mutated cases was distinct from the phenotype usually observed in M-D due to SGCE mutations. All cases initially presented with mild myoclonus affecting the upper limbs. Dystonia showed a progressive course, with increasing severity of symptoms and spreading from the cranio-cervical region to other sites. KCTD17 is abundantly expressed in all brain regions with the highest expression in the putamen. Weighted gene co-expression network analysis, based on mRNA expression profile of brain samples from neuropathologically healthy individuals, showed that KCTD17 is part of a putamen gene network, which is significantly enriched for dystonia genes. Functional annotation of the network showed an over-representation of genes involved in post-synaptic dopaminergic transmission. Functional studies in mutation bearing fibroblasts demonstrated abnormalities in endoplasmic reticulum-dependent calcium signaling. In conclusion, we demonstrate that the KCTD17 c.434 G>A p.(Arg145His) mutation causes autosomal dominant M-D. Further functional studies are warranted to further characterize the nature of KCTD17 contribution to the molecular pathogenesis of M-D. PMID:25983243

  6. A missense mutation in KCTD17 causes autosomal dominant myoclonus-dystonia.

    PubMed

    Mencacci, Niccolo E; Rubio-Agusti, Ignacio; Zdebik, Anselm; Asmus, Friedrich; Ludtmann, Marthe H R; Ryten, Mina; Plagnol, Vincent; Hauser, Ann-Kathrin; Bandres-Ciga, Sara; Bettencourt, Conceição; Forabosco, Paola; Hughes, Deborah; Soutar, Marc M P; Peall, Kathryn; Morris, Huw R; Trabzuni, Daniah; Tekman, Mehmet; Stanescu, Horia C; Kleta, Robert; Carecchio, Miryam; Zorzi, Giovanna; Nardocci, Nardo; Garavaglia, Barbara; Lohmann, Ebba; Weissbach, Anne; Klein, Christine; Hardy, John; Pittman, Alan M; Foltynie, Thomas; Abramov, Andrey Y; Gasser, Thomas; Bhatia, Kailash P; Wood, Nicholas W

    2015-06-01

    Myoclonus-dystonia (M-D) is a rare movement disorder characterized by a combination of non-epileptic myoclonic jerks and dystonia. SGCE mutations represent a major cause for familial M-D being responsible for 30%-50% of cases. After excluding SGCE mutations, we identified through a combination of linkage analysis and whole-exome sequencing KCTD17 c.434 G>A p.(Arg145His) as the only segregating variant in a dominant British pedigree with seven subjects affected by M-D. A subsequent screening in a cohort of M-D cases without mutations in SGCE revealed the same KCTD17 variant in a German family. The clinical presentation of the KCTD17-mutated cases was distinct from the phenotype usually observed in M-D due to SGCE mutations. All cases initially presented with mild myoclonus affecting the upper limbs. Dystonia showed a progressive course, with increasing severity of symptoms and spreading from the cranio-cervical region to other sites. KCTD17 is abundantly expressed in all brain regions with the highest expression in the putamen. Weighted gene co-expression network analysis, based on mRNA expression profile of brain samples from neuropathologically healthy individuals, showed that KCTD17 is part of a putamen gene network, which is significantly enriched for dystonia genes. Functional annotation of the network showed an over-representation of genes involved in post-synaptic dopaminergic transmission. Functional studies in mutation bearing fibroblasts demonstrated abnormalities in endoplasmic reticulum-dependent calcium signaling. In conclusion, we demonstrate that the KCTD17 c.434 G>A p.(Arg145His) mutation causes autosomal dominant M-D. Further functional studies are warranted to further characterize the nature of KCTD17 contribution to the molecular pathogenesis of M-D. PMID:25983243

  7. Two novel SRY missense mutations reducing DNA binding identified in XY females and their mosaic fathers

    SciTech Connect

    Schmitt-Ney, M.; Scherer, G.; Thiele, H.; KaltwaBer, P.; Bardoni, B.; Cisternino, M.

    1995-04-01

    Two novel mutations in the sex-determining gene SRY were identified by screening DNA from 30 sex-reversed XY females by using the SSCP assay. Both point mutations lead to an amino acid substitution in the DNA-binding high-mobility-group domain of the SRY protein. The first mutation, changing a serine at position 91 to glycine, was found in a sporadic case. The second mutation, leading to replacement of a highly conserved proline at position 125 with leucine, is shared by three members of the same family, two sisters and a half sister having the same father. The mutant SRY proteins showed reduced DNA-binding ability in a gel-shift assay. Analysis of lymphocyte DNA from the respective fathers revealed that they carry both the wild-type and the mutant version of the SRY gene. The fact that both fathers transmitted the mutant SRY copy to their offspring implies that they are mosaic for the SRY gene in testis as well as in blood, as a result of a mutation during early embryonic development. 30 refs., 5 figs.

  8. One missense mutation in exon 2 of the PAX5 gene in Iran.

    PubMed

    Yazdanparast, S; Khatami, S R; Galehdari, H; Jaseb, K

    2015-01-01

    The PAX5 gene, which encodes the B-cell specific activator protein, is one of the most important factors in determination of B-cell development. This gene is the main target of somatic mutations in acute B lymphoblastic leukemia (B-ALL). For example, point mutations, deletions, as well as other gene rearrangements may lead to several forms of B-cell malignancy. In this study, we obtained 50 blood samples from patients diagnosed with ALL, and screened for PAX5 mutations using sequencing in exons 1, 2 and 3. We found a heterozygous germline variant, c.113G>A (p.Arg38His), which affects the paired domain of PAX5. It seems that this mutation is pathogenic, but is recessive. Our findings suggest that this mutation in a single allele of the PAX5 gene is not sufficient to cause disease, and it is possible that other alleles are also involved in the onset of B-ALL. PMID:26782422

  9. Trafficking defects and loss of ligand binding are the underlying causes of all reported DDR2 missense mutations found in SMED-SL patients.

    PubMed

    Ali, Bassam R; Xu, Huifang; Akawi, Nadia A; John, Anne; Karuvantevida, Noushad S; Langer, Ruth; Al-Gazali, Lihadh; Leitinger, Birgit

    2010-06-01

    Spondylo-meta-epiphyseal dysplasia (SMED) with short limbs and abnormal calcifications (SMED-SL) is a rare, autosomal recessive human growth disorder, characterized by disproportionate short stature, short limbs, short broad fingers, abnormal metaphyses and epiphyses, platyspondyly and premature calcifications. Recently, three missense mutations and one splice-site mutation in the DDR2 gene were identified as causative genetic defects for SMED-SL, but the underlying cellular and biochemical mechanisms were not explored. Here we report a novel DDR2 missense mutation, c.337G>A (p.E113K), that causes SMED-SL in two siblings in the United Arab Emirates. Another DDR2 missense mutation, c.2254C>T (p.R752C), matching one of the previously reported SMED-SL mutations, was found in a second affected family. DDR2 is a plasma membrane receptor tyrosine kinase that functions as a collagen receptor. We expressed DDR2 constructs with the identified point mutations in human cell lines and evaluated their localization and functional properties. We found that all SMED-SL missense mutants were defective in collagen-induced receptor activation and that the three previously reported mutants (p.T713I, p.I726R and p.R752C) were retained in the endoplasmic reticulum. The novel mutant (p.E113K), in contrast, trafficked normally, like wild-type DDR2, but failed to bind collagen. This finding is in agreement with our recent structural data identifying Glu113 as an important amino acid in the DDR2 ligand-binding site. Our data thus demonstrate that SMED-SL can result from at least two different loss-of-function mechanisms: namely defects in DDR2 targeting to the plasma membrane or the loss of its ligand-binding activity. PMID:20223752

  10. A rare missense mutation in CHRNA4 associates with smoking behavior and its consequences.

    PubMed

    Thorgeirsson, T E; Steinberg, S; Reginsson, G W; Bjornsdottir, G; Rafnar, T; Jonsdottir, I; Helgadottir, A; Gretarsdottir, S; Helgadottir, H; Jonsson, S; Matthiasson, S E; Gislason, T; Tyrfingsson, T; Gudbjartsson, T; Isaksson, H J; Hardardottir, H; Sigvaldason, A; Kiemeney, L A; Haugen, A; Zienolddiny, S; Wolf, H J; Franklin, W A; Panadero, A; Mayordomo, J I; Hall, I P; Rönmark, E; Lundbäck, B; Dirksen, A; Ashraf, H; Pedersen, J H; Masson, G; Sulem, P; Thorsteinsdottir, U; Gudbjartsson, D F; Stefansson, K

    2016-05-01

    Using Icelandic whole-genome sequence data and an imputation approach we searched for rare sequence variants in CHRNA4 and tested them for association with nicotine dependence. We show that carriers of a rare missense variant (allele frequency=0.24%) within CHRNA4, encoding an R336C substitution, have greater risk of nicotine addiction than non-carriers as assessed by the Fagerstrom Test for Nicotine Dependence (P=1.2 × 10(-4)). The variant also confers risk of several serious smoking-related diseases previously shown to be associated with the D398N substitution in CHRNA5. We observed odds ratios (ORs) of 1.7-2.3 for lung cancer (LC; P=4.0 × 10(-4)), chronic obstructive pulmonary disease (COPD; P=9.3 × 10(-4)), peripheral artery disease (PAD; P=0.090) and abdominal aortic aneurysms (AAAs; P=0.12), and the variant associates strongly with the early-onset forms of LC (OR=4.49, P=2.2 × 10(-4)), COPD (OR=3.22, P=2.9 × 10(-4)), PAD (OR=3.47, P=9.2 × 10(-3)) and AAA (OR=6.44, P=6.3 × 10(-3)). Joint analysis of the four smoking-related diseases reveals significant association (P=6.8 × 10(-5)), particularly for early-onset cases (P=2.1 × 10(-7)). Our results are in agreement with functional studies showing that the human α4β2 isoform of the channel containing R336C has less sensitivity for its agonists than the wild-type form following nicotine incubation. PMID:26952864

  11. Mutation prediction by PolyPhen or functional assay, a detailed comparison of CYP27B1 missense mutations.

    PubMed

    Zou, Minjing; Baitei, Essa Y; Alzahrani, Ali S; Parhar, Ranjit S; Al-Mohanna, Futwan A; Meyer, Brian F; Shi, Yufei

    2011-08-01

    Vitamin D-dependent rickets type 1 (VDDR-I) is caused by mutation in CYP27B1. The glycine residue at codon 102 is not conserved between human (G(102)) and rodent (S(102)). G102E mutation results in 80% reduction in its enzymatic activity but PolyPhen predicts benign change. It is not known whether G102S has any damaging effect on 1α-hydroxylase activity. We investigated the effect of CYP27B1 (G102S) on its enzymatic activity and compared mutation prediction accuracy for all known CYP27B1 mutations among three free online protein prediction programs: PolyPhen, PolyPhen-2, and PSIPRED. G102S has no damaging effect on 1α-hydroxylase activity. G102D retained 30% enzymatic activity. All three programs correctly predicted damaging change for G102D. PolyPhen predicted benign change for G102S, whereas PolyPhen-2 and PSIPRED indicated possible damaging effect. Among 24 reported damaging mutations, PSIPRED, PolyPhen-2, and PolyPhen achieved 100%, 91.7% (22/24), and 75% (18/24) accuracy rate, respectively. The residues of incorrectly predicted mutations were not conserved. We conclude that G102D resulted in a significant reduction in 1α-hydroxylase activity, whereas G102S did not. PSIPRED and PolyPhen-2 are superior to PolyPhen in predicting damaging mutations. PMID:21604088

  12. Association of TMEM154 missense mutations with lentiviral infection and virus subtypes in sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Small ruminant lentivirus (SRLV) infections are a major cause of production losses in many sheep industries. Genetic susceptibility to SRLV infection in sheep is associated with the transmembrane protein 154 gene (TMEM154). A lysine mutation affecting the extracellular domain (K35, variant 1) is a...

  13. Molecular basis of variegate porphyria: a missense mutation in the protoporphyrinogen oxidase gene.

    PubMed Central

    Frank, J; Lam, H; Zaider, E; Poh-Fitzpatrick, M; Christiano, A M

    1998-01-01

    Variegate porphyria (VP) is an autosomal dominant disorder characterised by a partial defect in the activity of protoporphyrinogen oxidase (PPO), and has recently been genetically linked to the PPO gene on chromosome 1q22-23 (Z=6.62). In this study, we identified a mutation in the PPO gene in a patient with VP and two unaffected family members. The mutation consisted of a previously unreported T to C transition in exon 13 of the PPO gene, resulting in the substitution of a polar serine by a non-polar proline (S450P). This serine residue is evolutionarily highly conserved in man, mouse, and Bacillus subtilis, attesting to the importance of this residue. Interestingly, the gene for Gardner's syndrome (FAP) also segregates in this family, independently of the VP mutation. Gardner's syndrome or familial adenomatous polyposis (FAP) is also an autosomal dominantly inherited genodermatosis, and typically presents with colorectal cancer in early adult life secondary to extensive adenomatous polyps of the colon. The specific gene on chromosome 5 that is the site of the mutation in this disorder is known as APC (adenomatous polyposis coli), and the gene has been genetically linked to the region of 5q22. Images PMID:9541112

  14. Novel Missense Mutation A789V in IQSEC2 Underlies X-Linked Intellectual Disability in the MRX78 Family

    PubMed Central

    Kalscheuer, Vera M.; James, Victoria M.; Himelright, Miranda L.; Long, Philip; Oegema, Renske; Jensen, Corinna; Bienek, Melanie; Hu, Hao; Haas, Stefan A.; Topf, Maya; Hoogeboom, A. Jeannette M.; Harvey, Kirsten; Walikonis, Randall; Harvey, Robert J.

    2016-01-01

    Disease gene discovery in neurodevelopmental disorders, including X-linked intellectual disability (XLID) has recently been accelerated by next-generation DNA sequencing approaches. To date, more than 100 human X chromosome genes involved in neuronal signaling pathways and networks implicated in cognitive function have been identified. Despite these advances, the mutations underlying disease in a large number of XLID families remained unresolved. We report the resolution of MRX78, a large family with six affected males and seven affected females, showing X-linked inheritance. Although a previous linkage study had mapped the locus to the short arm of chromosome X (Xp11.4-p11.23), this region contained too many candidate genes to be analyzed using conventional approaches. However, our X-chromosome exome resequencing, bioinformatics analysis and inheritance testing revealed a missense mutation (c.C2366T, p.A789V) in IQSEC2, encoding a neuronal GDP-GTP exchange factor for Arf family GTPases (ArfGEF) previously implicated in XLID. Molecular modeling of IQSEC2 revealed that the A789V substitution results in the insertion of a larger side-chain into a hydrophobic pocket in the catalytic Sec7 domain of IQSEC2. The A789V change is predicted to result in numerous clashes with adjacent amino acids and disruption of local folding of the Sec7 domain. Consistent with this finding, functional assays revealed that recombinant IQSEC2A789V was not able to catalyze GDP-GTP exchange on Arf6 as efficiently as wild-type IQSEC2. Taken together, these results strongly suggest that the A789V mutation in IQSEC2 is the underlying cause of XLID in the MRX78 family. PMID:26793055

  15. A COLQ missense mutation in Labrador Retrievers having congenital myasthenic syndrome.

    PubMed

    Rinz, Caitlin J; Levine, Jonathan; Minor, Katie M; Humphries, Hammon D; Lara, Renee; Starr-Moss, Alison N; Guo, Ling T; Williams, D Colette; Shelton, G Diane; Clark, Leigh Anne

    2014-01-01

    Congenital myasthenic syndromes (CMSs) are heterogeneous neuromuscular disorders characterized by skeletal muscle weakness caused by disruption of signal transmission across the neuromuscular junction (NMJ). CMSs are rarely encountered in veterinary medicine, and causative mutations have only been identified in Old Danish Pointing Dogs and Brahman cattle to date. Herein, we characterize a novel CMS in 2 Labrador Retriever littermates with an early onset of marked generalized muscle weakness. Because the sire and dam share 2 recent common ancestors, CMS is likely the result of recessive alleles inherited identical by descent (IBD). Genome-wide SNP profiles generated from the Illumina HD array for 9 nuclear family members were used to determine genomic inheritance patterns in chromosomal regions encompassing 18 functional candidate genes. SNP haplotypes spanning 3 genes were consistent with autosomal recessive transmission, and microsatellite data showed that only the segment encompassing COLQ was inherited IBD. COLQ encodes the collagenous tail of acetylcholinesterase, the enzyme responsible for termination of signal transduction in the NMJ. Sequences from COLQ revealed a variant in exon 14 (c.1010T>C) that results in the substitution of a conserved amino acid (I337T) within the C-terminal domain. Both affected puppies were homozygous for this variant, and 16 relatives were heterozygous, while 288 unrelated Labrador Retrievers and 112 dogs of other breeds were wild-type. A recent study in which 2 human CMS patients were found to be homozygous for an identical COLQ mutation (c.1010T>C; I337T) provides further evidence that this mutation is pathogenic. This report describes the first COLQ mutation in canine CMS and demonstrates the utility of SNP profiles from nuclear family members for the identification of private mutations. PMID:25166616

  16. A COLQ Missense Mutation in Labrador Retrievers Having Congenital Myasthenic Syndrome

    PubMed Central

    Rinz, Caitlin J.; Levine, Jonathan; Minor, Katie M.; Humphries, Hammon D.; Lara, Renee; Starr-Moss, Alison N.; Guo, Ling T.; Williams, D. Colette; Shelton, G. Diane; Clark, Leigh Anne

    2014-01-01

    Congenital myasthenic syndromes (CMSs) are heterogeneous neuromuscular disorders characterized by skeletal muscle weakness caused by disruption of signal transmission across the neuromuscular junction (NMJ). CMSs are rarely encountered in veterinary medicine, and causative mutations have only been identified in Old Danish Pointing Dogs and Brahman cattle to date. Herein, we characterize a novel CMS in 2 Labrador Retriever littermates with an early onset of marked generalized muscle weakness. Because the sire and dam share 2 recent common ancestors, CMS is likely the result of recessive alleles inherited identical by descent (IBD). Genome-wide SNP profiles generated from the Illumina HD array for 9 nuclear family members were used to determine genomic inheritance patterns in chromosomal regions encompassing 18 functional candidate genes. SNP haplotypes spanning 3 genes were consistent with autosomal recessive transmission, and microsatellite data showed that only the segment encompassing COLQ was inherited IBD. COLQ encodes the collagenous tail of acetylcholinesterase, the enzyme responsible for termination of signal transduction in the NMJ. Sequences from COLQ revealed a variant in exon 14 (c.1010T>C) that results in the substitution of a conserved amino acid (I337T) within the C-terminal domain. Both affected puppies were homozygous for this variant, and 16 relatives were heterozygous, while 288 unrelated Labrador Retrievers and 112 dogs of other breeds were wild-type. A recent study in which 2 human CMS patients were found to be homozygous for an identical COLQ mutation (c.1010T>C; I337T) provides further evidence that this mutation is pathogenic. This report describes the first COLQ mutation in canine CMS and demonstrates the utility of SNP profiles from nuclear family members for the identification of private mutations. PMID:25166616

  17. Mismatch repair genes Mlh1 and Mlh3 modify CAG instability in Huntington's disease mice: genome-wide and candidate approaches.

    PubMed

    Pinto, Ricardo Mouro; Dragileva, Ella; Kirby, Andrew; Lloret, Alejandro; Lopez, Edith; St Claire, Jason; Panigrahi, Gagan B; Hou, Caixia; Holloway, Kim; Gillis, Tammy; Guide, Jolene R; Cohen, Paula E; Li, Guo-Min; Pearson, Christopher E; Daly, Mark J; Wheeler, Vanessa C

    2013-10-01

    The Huntington's disease gene (HTT) CAG repeat mutation undergoes somatic expansion that correlates with pathogenesis. Modifiers of somatic expansion may therefore provide routes for therapies targeting the underlying mutation, an approach that is likely applicable to other trinucleotide repeat diseases. Huntington's disease Hdh(Q111) mice exhibit higher levels of somatic HTT CAG expansion on a C57BL/6 genetic background (B6.Hdh(Q111) ) than on a 129 background (129.Hdh(Q111) ). Linkage mapping in (B6x129).Hdh(Q111) F2 intercross animals identified a single quantitative trait locus underlying the strain-specific difference in expansion in the striatum, implicating mismatch repair (MMR) gene Mlh1 as the most likely candidate modifier. Crossing B6.Hdh(Q111) mice onto an Mlh1 null background demonstrated that Mlh1 is essential for somatic CAG expansions and that it is an enhancer of nuclear huntingtin accumulation in striatal neurons. Hdh(Q111) somatic expansion was also abolished in mice deficient in the Mlh3 gene, implicating MutLγ (MLH1-MLH3) complex as a key driver of somatic expansion. Strikingly, Mlh1 and Mlh3 genes encoding MMR effector proteins were as critical to somatic expansion as Msh2 and Msh3 genes encoding DNA mismatch recognition complex MutSβ (MSH2-MSH3). The Mlh1 locus is highly polymorphic between B6 and 129 strains. While we were unable to detect any difference in base-base mismatch or short slipped-repeat repair activity between B6 and 129 MLH1 variants, repair efficiency was MLH1 dose-dependent. MLH1 mRNA and protein levels were significantly decreased in 129 mice compared to B6 mice, consistent with a dose-sensitive MLH1-dependent DNA repair mechanism underlying the somatic expansion difference between these strains. Together, these data identify Mlh1 and Mlh3 as novel critical genetic modifiers of HTT CAG instability, point to Mlh1 genetic variation as the likely source of the instability difference in B6 and 129 strains and suggest that MLH1

  18. A new glucocerebrosidase-gene missense mutation responsible for neuronopathic Gaucher disease in Japanese patients.

    PubMed Central

    Kawame, H; Eto, Y

    1991-01-01

    We have identified a new T-to-A single-base substitution at nucleotide 3548 (in the genomic sequence) in exon 6 in the glucocerebrosidase gene from a patient with Gaucher disease type 3. This mutation caused a substitution of isoleucine for phenylalanine at amino acid residue 213 (of 497 residues in the mature protein). By in vitro expression study in cultured mammalian cells, this mutation resulted in deficient activity of glucocerebrosidase. By allele-specific oligonucleotide hybridization of selectively PCR-amplified DNA from eight unrelated Japanese Gaucher disease patients, this mutant allele was observed in other neuronopathic Japanese Gaucher disease patients, in moderately frequent occurrence (three of six neuronopathic patients). This observation suggests that this allele was one of severe [corrected] alleles which were related to the development of neurological manifestations of Gaucher disease. Images Figure 1 Figure 2 PMID:1840477

  19. Cystic fibrosis mice carrying the missense mutation G551D replicate human genotype-phenotype correlations.

    PubMed Central

    Delaney, S J; Alton, E W; Smith, S N; Lunn, D P; Farley, R; Lovelock, P K; Thomson, S A; Hume, D A; Lamb, D; Porteous, D J; Dorin, J R; Wainwright, B J

    1996-01-01

    We have generated a mouse carrying the human G551D mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a one-step gene targeting procedure. These mutant mice show cystic fibrosis pathology but have a reduced risk of fatal intestinal blockage compared with 'null' mutants, in keeping with the reduced incidence of meconium ileus in G551D patients. The G551D mutant mice show greatly reduced CFTR-related chloride transport, displaying activity intermediate between that of cftr(mlUNC) replacement ('null') and cftr(mlHGU) insertional (residual activity) mutants and equivalent to approximately 4% of wild-type CFTR activity. The long-term survival of these animals should provide an excellent model with which to study cystic fibrosis, and they illustrate the value of mouse models carrying relevant mutations for examining genotype-phenotype correlations. Images PMID:8605891

  20. Keratin 12 missense mutation induces the unfolded protein response and apoptosis in Meesmann epithelial corneal dystrophy

    PubMed Central

    Allen, Edwin H.A.; Courtney, David G.; Atkinson, Sarah D.; Moore, Johnny E.; Mairs, Laura; Poulsen, Ebbe Toftgaard; Schiroli, Davide; Maurizi, Eleonora; Cole, Christian; Hickerson, Robyn P.; James, John; Murgatroyd, Helen; Smith, Frances J.D.; MacEwen, Carrie; Enghild, Jan J.; Nesbit, M. Andrew; Leslie Pedrioli, Deena M.; McLean, W.H. Irwin; Moore, C.B. Tara

    2016-01-01

    Meesmann epithelial corneal dystrophy (MECD) is a rare autosomal dominant disorder caused by dominant-negative mutations within the KRT3 or KRT12 genes, which encode the cytoskeletal protein keratins K3 and K12, respectively. To investigate the pathomechanism of this disease, we generated and phenotypically characterized a novel knock-in humanized mouse model carrying the severe, MECD-associated, K12-Leu132Pro mutation. Although no overt changes in corneal opacity were detected by slit-lamp examination, the corneas of homozygous mutant mice exhibited histological and ultrastructural epithelial cell fragility phenotypes. An altered keratin expression profile was observed in the cornea of mutant mice, confirmed by western blot, RNA-seq and quantitative real-time polymerase chain reaction. Mass spectrometry (MS) and immunohistochemistry demonstrated a similarly altered keratin profile in corneal tissue from a K12-Leu132Pro MECD patient. The K12-Leu132Pro mutation results in cytoplasmic keratin aggregates. RNA-seq analysis revealed increased chaperone gene expression, and apoptotic unfolded protein response (UPR) markers, CHOP and Caspase 12, were also increased in the MECD mice. Corneal epithelial cell apoptosis was increased 17-fold in the mutant cornea, compared with the wild-type (P < 0.001). This elevation of UPR marker expression was also observed in the human MECD cornea. This is the first reporting of a mouse model for MECD that recapitulates the human disease and is a valuable resource in understanding the pathomechanism of the disease. Although the most severe phenotype is observed in the homozygous mice, this model will still provide a test-bed for therapies not only for corneal dystrophies but also for other keratinopathies caused by similar mutations. PMID:26758872

  1. Missense mutation T485S alters NBCe1-A electrogenicity causing proximal renal tubular acidosis.

    PubMed

    Zhu, Quansheng; Shao, Xuesi M; Kao, Liyo; Azimov, Rustam; Weinstein, Alan M; Newman, Debra; Liu, Weixin; Kurtz, Ira

    2013-08-15

    Mutations in SLC4A4, the gene encoding the electrogenic Na(+)-HCO3(-) cotransporter NBCe1, cause severe proximal renal tubular acidosis (pRTA), growth retardation, decreased IQ, and eye and teeth abnormalities. Among the known NBCe1 mutations, the disease-causing mechanism of the T485S (NBCe1-A numbering) mutation is intriguing because the substituted amino acid, serine, is structurally and chemically similar to threonine. In this study, we performed intracellular pH and whole cell patch-clamp measurements to investigate the base transport and electrogenic properties of NBCe1-A-T485S in mammalian HEK 293 cells. Our results demonstrated that Ser substitution of Thr485 decreased base transport by ~50%, and importantly, converted NBCe1-A from an electrogenic to an electroneutral transporter. Aqueous accessibility analysis using sulfhydryl reactive reagents indicated that Thr485 likely resides in an NBCe1-A ion interaction site. This critical location is also supported by the finding that G486R (a pRTA causing mutation) alters the position of Thr485 in NBCe1-A thereby impairing its transport function. By using NO3(-) as a surrogate ion for CO3(2-), our result indicated that NBCe1-A mediates electrogenic Na(+)-CO3(2-) cotransport when functioning with a 1:2 charge transport stoichiometry. In contrast, electroneutral NBCe1-T485S is unable to transport NO3(-), compatible with the hypothesis that it mediates Na(+)-HCO3(-) cotransport. In patients, NBCe1-A-T485S is predicted to transport Na(+)-HCO3(-) in the reverse direction from blood into proximal tubule cells thereby impairing transepithelial HCO3(-) absorption, possibly representing a new pathogenic mechanism for generating human pRTA. PMID:23636456

  2. Novel missense mutation in the cyclic nucleotide-binding domain of HERG causes long QT syndrome

    SciTech Connect

    Satler, C.A.; Walsh, E.P.; Vesely, M.R.

    1996-10-02

    Autosomal-dominant long QT syndrome (LQT) is an inherited disorder, predisposing affected individuals to sudden death from tachyarrhythmias. To identify the gene(s) responsible for LQT, we identified and characterized an LQT family consisting of 48 individuals. DNA was screened with 150 microsatellite polymorphic markers encompassing approximately 70% of the genome. We found evidence for linkage of the LQT phenotype to chromosome 7(q35-36). Marker D7S636 yielded a maximum lod score of 6.93 at a recombination fraction ({theta}) of 0.00. Haplotype analysis further localized the LQT gene within a 6-2-cM interval. HERG encodes a potassium channel which has been mapped to this region. Single-strand conformational polymorphism analyses demonstrated aberrant bands that were unique to all affected individuals. DNA sequencing of the aberrant bands demonstrated a G to A substitution in all affected patients; this point mutation results in the substitution of a highly conserved valine residue with a methionine (V822M) in the cyclic nucleotide-binding domain of this potassium channel. The cosegregation of this distinct mutation with LQT demonstrates that HERG is the LQT gene in this pedigree. Furthermore, the location and character of this mutation suggests that the cyclic nucleotide-binding domain of the potassium channel encoded by HERG plays an important role in normal cardiac repolarization and may decrease susceptibility to ventricular tachyarrhythmias. 38 refs., 7 figs., 2 tabs.

  3. Functional and structural impact of the most prevalent missense mutations in classic galactosemia.

    PubMed

    Coelho, Ana I; Trabuco, Matilde; Ramos, Ruben; Silva, Maria João; Tavares de Almeida, Isabel; Leandro, Paula; Rivera, Isabel; Vicente, João B

    2014-11-01

    Galactose-1-phosphate uridylyltransferase (GALT) is a key enzyme in galactose metabolism, particularly important in the neonatal period due to ingestion of galactose-containing milk. GALT deficiency results in the genetic disorder classic galactosemia, whose pathophysiology is still not fully elucidated. Whereas classic galactosemia has been hypothesized to result from GALT misfolding, a thorough functional-structural characterization of GALT most prevalent variants was still lacking, hampering the development of alternative therapeutic approaches. The aim of this study was to investigate the structural-functional effects of nine GALT mutations, four of which account for the vast majority of the mutations identified in galactosemic patients. Several methodologies were employed to evaluate the mutations' impact on GALT function, on the protein secondary and tertiary structures, and on the aggregation propensity. The major structural effect concerns disturbed propensity for aggregation, particularly striking for the p.Q188R variant, resulting from the most frequent (∼60%) allele at a worldwide scale. The absence of major effects at the secondary and tertiary structure levels suggests that the disturbed aggregation results from subtle perturbations causing a higher and/or longer exposure of hydrophobic residues in the variants as compared to WT GALT. The results herein described indicate a possible benefit from introducing proteostasis regulators and/or chemical/pharmacological chaperones to prevent the accumulation of protein aggregates, in new avenues of therapeutic research for classic galactosemia. PMID:25614870

  4. Whole Exome Sequencing Leading to the Diagnosis of Dysferlinopathy with a Novel Missense Mutation (c.959G>C)

    PubMed Central

    Swaika, Abhisek; Boczek, Nicole J.; Sood, Neha; Guthrie, Kimberly; Klee, Eric W.; Agrawal, Ankit; Dimberg, Elliot L.; Ailawadhi, Sikander

    2016-01-01

    Dysferlinopathy is an uncommon, progressive muscular dystrophy that has a wide phenotypic variability and primarily supportive management (Nguyen et al., 2007; Narayanaswami et al., 2014). Amyloid myopathy is a distinct, rare disorder that can present similarly to inflammatory myopathies and requires a high clinical suspicion for early intervention to prolong survival. Amyloid myopathy is typically associated with other systemic manifestations of amyloidosis, but rare cases of isolated amyloid myopathy have been described (Mandl et al., 2000; Hull et al., 2001). Positive Congo red stains on tissue biopsy remain the gold standard for diagnosis (Spuler et al., 1998; Karacostas et al., 2005). A high clinical suspicion and meticulous diagnostic workup that includes novel techniques are necessary for identifying these rare disorders. We report a middle-aged man with progressive leg muscle weakness who was initially treated as having amyloid myopathy but was later diagnosed as having dysferlinopathy by Whole Exome Sequencing (WES) analysis. We also report a novel missense mutation (c.959G>C) to help correlate in any patient with presumed dysferlinopathy and to add to the already known genotype of this disorder. PMID:27195159

  5. A missense mutation (p.G274R) in gene ASPA causes Canavan disease in a Pakistani family.

    PubMed

    Hussain, Rashida; Daud, Shakeela; Kakar, Naseebullah; Ahmad, Adeel; Baloch, Abdul Hameed; Tareen, Abdul Malik; Kakar, Muhammad Azam; Ahmad, Jamil

    2012-05-01

    Canavan disease (OMIM 271900) is an autosomal recessive lethal neurodegenerative disorder characterized by spongy degeneration of the brain. A highly consanguineous Pakistani family with Canavan disease was enrolled on the basis of diagnosis. All the affected individuals have mental retardation, megalocephaly and degradation of motor skills, poor head control, partial vision loss, weakness of the muscles and raised urinary concentration of N-acetyl aspartic acid in the urine. Blood samples were collected from affected as well as normal siblings and processed for DNA purification. Linkage analysis was performed by typing three short tandem repeat markers D17S1583 (7.19 cM), D17S1828 (10.02 cM) and D17S919 (14.69 cM) for an already-reported gene/locus ASPA at chromosome 17p13.2 causing Canavan disease. During linkage analysis, all the affected individuals were homozygous for short tandem repeat markers while the normal siblings were heterozygous showing co-segregation of the disease. Gene ASPA (NM_000049) was undertaken to sequence for mutation analysis. As a result of sequence analysis, we found missense substitution 740A→G (p.G274R) in exon 6 of gene ASPA. To our knowledge, this is the first report about Canavan disease on a Pakistani family. PMID:22219087

  6. Missense mutation in the ATPase, aminophospholipid transporter protein ATP8A2 is associated with cerebellar atrophy and quadrupedal locomotion

    PubMed Central

    Emre Onat, Onur; Gulsuner, Suleyman; Bilguvar, Kaya; Nazli Basak, Ayse; Topaloglu, Haluk; Tan, Meliha; Tan, Uner; Gunel, Murat; Ozcelik, Tayfun

    2013-01-01

    Cerebellar ataxia, mental retardation and dysequilibrium syndrome is a rare and heterogeneous condition. We investigated a consanguineous family from Turkey with four affected individuals exhibiting the condition. Homozygosity mapping revealed that several shared homozygous regions, including chromosome 13q12. Targeted next-generation sequencing of an affected individual followed by segregation analysis, population screening and prediction approaches revealed a novel missense variant, p.I376M, in ATP8A2. The mutation lies in a highly conserved C-terminal transmembrane region of E1 E2 ATPase domain. The ATP8A2 gene is mainly expressed in brain and development, in particular cerebellum. Interestingly, an unrelated individual has been identified, in whom mental retardation and severe hypotonia is associated with a de novo t(10;13) balanced translocation resulting with the disruption of ATP8A2. These findings suggest that ATP8A2 is involved in the development of the cerebro-cerebellar structures required for posture and gait in humans. PMID:22892528

  7. Whole Genome Sequencing Identifies a Missense Mutation in HES7 Associated with Short Tails in Asian Domestic Cats

    PubMed Central

    Xu, Xiao; Sun, Xin; Hu, Xue-Song; Zhuang, Yan; Liu, Yue-Chen; Meng, Hao; Miao, Lin; Yu, He; Luo, Shu-Jin

    2016-01-01

    Domestic cats exhibit abundant variations in tail morphology and serve as an excellent model to study the development and evolution of vertebrate tails. Cats with shortened and kinked tails were first recorded in the Malayan archipelago by Charles Darwin in 1868 and remain quite common today in Southeast and East Asia. To elucidate the genetic basis of short tails in Asian cats, we built a pedigree of 13 cats segregating at the trait with a founder from southern China and performed linkage mapping based on whole genome sequencing data from the pedigree. The short-tailed trait was mapped to a 5.6 Mb region of Chr E1, within which the substitution c. 5T > C in the somite segmentation-related gene HES7 was identified as the causal mutation resulting in a missense change (p.V2A). Validation in 245 unrelated cats confirmed the correlation between HES7-c. 5T > C and Chinese short-tailed feral cats as well as the Japanese Bobtail breed, indicating a common genetic basis of the two. In addition, some of our sampled kinked-tailed cats could not be explained by either HES7 or the Manx-related T-box, suggesting at least three independent events in the evolution of domestic cats giving rise to short-tailed traits. PMID:27560986

  8. Whole Genome Sequencing Identifies a Missense Mutation in HES7 Associated with Short Tails in Asian Domestic Cats.

    PubMed

    Xu, Xiao; Sun, Xin; Hu, Xue-Song; Zhuang, Yan; Liu, Yue-Chen; Meng, Hao; Miao, Lin; Yu, He; Luo, Shu-Jin

    2016-01-01

    Domestic cats exhibit abundant variations in tail morphology and serve as an excellent model to study the development and evolution of vertebrate tails. Cats with shortened and kinked tails were first recorded in the Malayan archipelago by Charles Darwin in 1868 and remain quite common today in Southeast and East Asia. To elucidate the genetic basis of short tails in Asian cats, we built a pedigree of 13 cats segregating at the trait with a founder from southern China and performed linkage mapping based on whole genome sequencing data from the pedigree. The short-tailed trait was mapped to a 5.6 Mb region of Chr E1, within which the substitution c. 5T > C in the somite segmentation-related gene HES7 was identified as the causal mutation resulting in a missense change (p.V2A). Validation in 245 unrelated cats confirmed the correlation between HES7-c. 5T > C and Chinese short-tailed feral cats as well as the Japanese Bobtail breed, indicating a common genetic basis of the two. In addition, some of our sampled kinked-tailed cats could not be explained by either HES7 or the Manx-related T-box, suggesting at least three independent events in the evolution of domestic cats giving rise to short-tailed traits. PMID:27560986

  9. A missense mutation in TFRC, encoding transferrin receptor 1, causes combined immunodeficiency

    PubMed Central

    Jabara, Haifa H.; Boyden, Steven E.; Chou, Janet; Ramesh, Narayanaswamy; Massaad, Michel J.; Benson, Halli; Bainter, Wayne; Fraulino, David; Rahimov, Fedik; Sieff, Colin; Liu, Zhi-Jian; Alshemmari, Salem H.; Al-Ramadi, Basel K.; Al-Dhekri, Hasan; Arnaout, Rand; Abu-Shukair, Mohammad; Vatsayan, Anant; Silver, Eli; Ahuja, Sanjay; Davies, E. Graham; Sola-Visner, Martha; Ohsumi, Toshiro K.; Andrews, Nancy C.; Notarangelo, Luigi D.; Fleming, Mark D.; Al-Herz, Waleed; Kunkel, Louis M.; Geha, Raif S.

    2015-01-01

    Patients with a combined immunodeficiency characterized by normal numbers, but impaired function, of T and B cells had a homozygous p.Tyr20His mutation in transferrin receptor 1 (TfR1), encoded by TFRC. The mutation disrupts the TfR1 internalization motif, resulting in defective receptor endocytosis and markedly increased TfR1 surface expression. Iron citrate rescued the lymphocyte defects and transduction of wild type, but not mutant, TfR1 rescued impaired transferrin uptake in patient fibroblasts. TfrcY20H/Y20H mice recapitulated the patients’ immunologic defects. Despite the critical role of TfR1 in erythrocyte development and function, the patients had only mild anemia and only slightly increased TfR1 expression in erythroid precursors. We show that STEAP3, a metalloreductase expressed in erythroblasts, associates with TfR1 and partially rescues transferrin uptake in patient fibroblasts, suggesting that STEAP3 may provide an accessory TfR1 endocytosis signal that spares the patients from severe anemia. These findings demonstrate the importance of TfR1 in adaptive immunity. PMID:26642240

  10. Hydrolethalus syndrome is caused by a missense mutation in a novel gene HYLS1.

    PubMed

    Mee, Lisa; Honkala, Heli; Kopra, Outi; Vesa, Jouni; Finnilä, Saara; Visapää, Ilona; Sang, Tzu-Kang; Jackson, George R; Salonen, Riitta; Kestilä, Marjo; Peltonen, Leena

    2005-06-01

    Hydrolethalus syndrome (HLS) is an autosomal recessive lethal malformation syndrome characterized by multiple developmental defects of fetus. We have earlier mapped and restricted the HLS region to a critical 1 cM interval on 11q23-25. The linkage disequilibrium (LD) and haplotype analyses of single nucleotide polymorphism (SNP) markers helped to further restrict the HLS locus to 476 kb between genes PKNOX2 and DDX25. An HLS associated mutation was identified in a novel regional transcript (GenBank accession no. FLJ32915), referred to here as the HYLS1 gene. The identified A to G transition results in a D211G change in the 299 amino acid polypeptide with unknown function. The HYLS1 gene shows alternative splicing and the transcript is found in multiple tissues during fetal development. In situ hybridization shows spatial and temporal distributions of transcripts in good agreement with the tissue phenotype of HLS patients. Immunostaining of in vitro expressed polypeptides from wild-type (WT) cDNA revealed cytoplasmic staining, whereas mutant polypeptides became localized in distinct nuclear structures, implying a disturbed cellular localization of the mutant protein. The Drosophila melanogaster model confirmed these findings and provides evidence for the significance of the mutation both in vitro and in vivo. PMID:15843405

  11. Rapid Proteasomal Degradation of Mutant Proteins Is the Primary Mechanism Leading to Tumorigenesis in Patients With Missense AIP Mutations

    PubMed Central

    Hernández-Ramírez, Laura C.; Martucci, Federico; Morgan, Rhodri M. L.; Trivellin, Giampaolo; Tilley, Daniel; Ramos-Guajardo, Nancy; Iacovazzo, Donato; D'Acquisto, Fulvio; Prodromou, Chrisostomos

    2016-01-01

    Context: The pathogenic effect of mutations in the aryl hydrocarbon receptor interacting protein (AIP) gene (AIPmuts) in pituitary adenomas is incompletely understood. We have identified the primary mechanism of loss of function for missense AIPmuts. Objective: This study sought to analyze the mechanism/speed of protein turnover of wild-type and missense AIP variants, correlating protein half-life with clinical parameters. Design and Setting: Half-life and protein–protein interaction experiments and cross-sectional analysis of AIPmut positive patients' data were performed in a clinical academic research institution. Patients: Data were obtained from our cohort of pituitary adenoma patients and literature-reported cases. Interventions: Protein turnover of endogenous AIP in two cell lines and fifteen AIP variants overexpressed in HEK293 cells was analyzed via cycloheximide chase and proteasome inhibition. Glutathione-S-transferase pull-down and quantitative mass spectrometry identified proteins involved in AIP degradation; results were confirmed by coimmunoprecipitation and gene knockdown. Relevant clinical data was collected. Main Outcome Measures: Half-life of wild-type and mutant AIP proteins and its correlation with clinical parameters. Results: Endogenous AIP half-life was similar in HEK293 and lymphoblastoid cells (43.5 and 32.7 h). AIP variants were divided into stable proteins (median, 77.7 h; interquartile range [IQR], 60.7–92.9 h), and those with short (median, 27 h; IQR, 21.6–28.7 h) or very short (median, 7.7 h; IQR, 5.6–10.5 h) half-life; proteasomal inhibition rescued the rapid degradation of mutant proteins. The experimental half-life significantly correlated with age at diagnosis of acromegaly/gigantism (r = 0.411; P = .002). The FBXO3-containing SKP1–CUL1–F-box protein complex was identified as the E3 ubiquitin-ligase recognizing AIP. Conclusions: AIP is a stable protein, driven to ubiquitination by the SKP1–CUL1–F-box protein complex

  12. A missense mutation in domain III in HSPG2 in Schwartz-Jampel syndrome compromises secretion of perlecan into the extracellular space.

    PubMed

    Iwata, Satoshi; Ito, Mikako; Nakata, Tomohiko; Noguchi, Yoichiro; Okuno, Tatsuya; Ohkawara, Bisei; Masuda, Akio; Goto, Tomohide; Adachi, Masanori; Osaka, Hitoshi; Nonaka, Risa; Arikawa-Hirasawa, Eri; Ohno, Kinji

    2015-08-01

    Schwartz-Jampel syndrome (SJS) type 1 is characterized by short stature, myotonia, and chondrodysplasia, and is caused by partial loss-of-function mutations in HSPG2 encoding perlecan. Six missense mutations have been reported in SJS to date and only one has been characterized using a recombinant protein. We report an 11-year-old Japanese boy with SJS, who shows "rigid" walking with less flexion of knees/ankles and protruded mouth. His intelligence is normal. We identified by whole genome resequencing a heterozygous missense p.Leu1088Pro in domain III-2 and a heterozygous nonsense p.Gln3061Ter in domain IV of perlecan. Expression studies revealed that p.Leu1088Pro markedly reduces the cellular expression of domain III-2 and almost nullifies its secretion into the culture medium. As five of the seven missense mutations in SJS affect domain III of perlecan, domain III is likely to be essential for secretion of perlecan into the extracellular space. PMID:26031903

  13. Identification of a missense mutation and several polymorphisms in the proenkephalin A gene of schizophrenic patients

    SciTech Connect

    Mikesell, M.J.; Sommer, S.S.; McMurray, C.T.

    1996-09-20

    Schizophrenia is a complex and severe disorder of unknown cause and pathophysiology. In this study, we examined the opioid hypothesis for schizophrenia at the molecular level, focusing on the dopamine-regulated proenkephalin A gene (chromosome 8q11.23-q12). We have screened 150 schizophrenic patients for sequence variations within the promoter region, entire coding sequence, and 3{prime}-untranslated region. We find one sequence change in a conserved amino acid that may be of functional significance. This mutation was found in a single schizophrenia patient but not in controls. Although several new, race-specific polymorphisms were identified, all other sequence changes appeared to be common polymorphisms, unlikely to contribute to the etiology of schizophrenia. 38 refs., 3 figs., 2 tabs.

  14. Extragenic suppression of motA missense mutations of Escherichia coli.

    PubMed Central

    Garza, A G; Bronstein, P A; Valdez, P A; Harris-Haller, L W; Manson, M D

    1996-01-01

    The MotA and MotB proteins are thought to comprise elements of the stator component of the flagellar motor of Escherichia coli. In an effort to understand interactions among proteins within the motor, we attempted to identify extragenic suppressors of 31 dominant, plasmid-borne alleles of motA. Strains containing these mutations were either nonmotile or had severely impaired motility. Four of the mutants yielded extragenic suppressors mapping to the FlaII or FlaIIIB regions of the chromosome. Two types of suppression were observed. Suppression of one type (class I) probably results from increased expression of the chromosomal motB gene due to relief of polarity. Class I suppressors were partial deletions of Mu insertion sequences in the disrupted chromosomal motA gene. Class I suppression was mimicked by expressing the wild-type MotB protein from a second, compatible plasmid. Suppression of the other type (class II) was weaker, and it was not mimicked by overproduction of wild-type MotB protein. Class II suppressors were point mutations in the chromosomal motB or fliG genes. Among 14 independent class II suppressors characterized by DNA sequencing, we identified six different amino acid substitutions in MotB and one substitution in FliG. A number of the strongest class II suppressors had alterations of residues 136 to 138 of MotB. This particular region within the large, C-terminal periplasmic domain of MotB has previously not been associated with a specific function. We suggest that residues 136 to 138 of MotB may interact directly with the periplasmic face of MotA or help position the N-terminal membrane-spanning helix of MotB properly to interact with the membrane-spanning helices of the MotA proton channel. PMID:8892808

  15. Identification of a novel nonsense mutation and a missense substitution in the AGPAT2 gene causing congenital generalized lipodystrophy type 1

    PubMed Central

    Haghighi, Amirreza; Razzaghy-Azar, Maryam; Talea, Ali; Sadeghian, Mahnaz; Ellard, Sian; Haghighi, Alireza

    2012-01-01

    Congenital generalized lipodystrophy (CGL) is an autosomal recessive disease characterized by the generalized scant of adipose tissue. CGL type 1 is caused by mutations in gene encoding 1-acylglycerol-3-phosphate O-acyltransferase-2 (AGPAT2). A clinical and molecular genetic investigation was performed in affected and unaffected members of two families with CGL type 1. The AGPAT2 coding region was sequenced in index cases of the two families. The presence of the identified mutations in relevant parents was tested. We identified a novel nonsense mutation (c.685G>T, p.Glu229*) and a missense substitution (c.514G>A, p.Glu172Lys). The unaffected parents in both families were heterozygous carrier of the relevant mutation. The results expand genotype–phenotype spectrum in CGL1 and will have applications in prenatal and early diagnosis of the disease. This is the first report of Persian families identified with AGPAT2 mutations. PMID:22902344

  16. A novel missense mutation of RYR1 in familial idiopathic hyper CK-emia.

    PubMed

    Sano, Ken; Miura, Shiroh; Fujiwara, Toshiya; Fujioka, Ryuta; Yorita, Akiko; Noda, Kazuhito; Kida, Hiroshi; Azuma, Koichi; Kaieda, Shinjiro; Yamamoto, Ken; Taniwaki, Takayuki; Fukumaki, Yasuyuki; Shibata, Hiroki

    2015-09-15

    Persistent elevation of serum creatine kinase (CK) without any symptoms has been called idiopathic hyper CK-emia (IHCK). We examined a four-generation Japanese pedigree of familial IHCK. The multipoint linkage analysis of the pedigree showed seven clear peaks of logarithm of odds (LOD) scores (>1.4). By the exome sequencing followed by multiple filtering processes, we identified one novel heterozygous nonsynonymous single nucleotide variant (SNV), c.7034G>C, p.S2345T in the ryanodine receptor 1 gene, RYR1 cosegregated with IHCK in the pedigree. Mutation Taster predicted this substitution as "disease causing" (p=0.999). The PolyPhen-2 and PANTHER subPSEC scores for the substitution are 0.911 (possibly damaging) and -3.56 (probably damaging), respectively. We confirmed the absence of the SNV in 511 healthy Japanese individuals excluding the possibility of a normal variant with a very low frequency. Immunohistochemistry and Western blotting of biopsy samples consistently showed the expression level of RYR1 reduced in the patient. In real-time RT-PCR, the mRNA expression level of RYR1 was also significantly reduced in the patient (p=0.009). These results suggest that the novel nonsynonymous SNV contribute to the vulnerability of the RYR1 protein through the dominant negative effect. We conclude that the SNV in the RYR1 gene is one of the responsible genes of IHCK. PMID:26119398

  17. Dominant missense mutations in a novel yeast protein related to mammalian phosphatidylinositol 3-kinase and VPS34 abrogate rapamycin cytotoxicity.

    PubMed Central

    Cafferkey, R; Young, P R; McLaughlin, M M; Bergsma, D J; Koltin, Y; Sathe, G M; Faucette, L; Eng, W K; Johnson, R K; Livi, G P

    1993-01-01

    Rapamycin is a macrolide antifungal agent that exhibits potent immunosuppressive properties. In Saccharomyces cerevisiae, rapamycin sensitivity is mediated by a specific cytoplasmic receptor which is a homolog of human FKBP12 (hFKBP12). Deletion of the gene for yeast FKBP12 (RBP1) results in recessive drug resistance, and expression of hFKBP12 restores rapamycin sensitivity. These data support the idea that FKBP12 and rapamycin form a toxic complex that corrupts the function of other cellular proteins. To identify such proteins, we isolated dominant rapamycin-resistant mutants both in wild-type haploid and diploid cells and in haploid rbp1::URA3 cells engineered to express hFKBP12. Genetic analysis indicated that the dominant mutations are nonallelic to mutations in RBP1 and define two genes, designated DRR1 and DRR2 (for dominant rapamycin resistance). Mutant copies of DRR1 and DRR2 were cloned from genomic YCp50 libraries by their ability to confer drug resistance in wild-type cells. DNA sequence analysis of a mutant drr1 allele revealed a long open reading frame predicting a novel 2470-amino-acid protein with several motifs suggesting an involvement in intracellular signal transduction, including a leucine zipper near the N terminus, two putative DNA-binding sequences, and a domain that exhibits significant sequence similarity to the 110-kDa catalytic subunit of both yeast (VPS34) and bovine phosphatidylinositol 3-kinases. Genomic disruption of DRR1 in a mutant haploid strain restored drug sensitivity and demonstrated that the gene encodes a nonessential function. DNA sequence comparison of seven independent drr1dom alleles identified single base pair substitutions in the same codon within the phosphatidylinositol 3-kinase domain, resulting in a change of Ser-1972 to Arg or Asn. We conclude either that DRR1 (alone or in combination with DRR2) acts as a target of FKBP12-rapamycin complexes or that a missense mutation in DRR1 allows it to compensate for the

  18. Cervical artery dissections and type A aortic dissection in a family with a novel missense COL3A1 mutation of vascular type Ehlers-Danlos syndrome.

    PubMed

    Makrygiannis, Georgios; Loeys, Bart; Defraigne, Jean-Olivier; Sakalihasan, Natzi

    2015-11-01

    Cervical artery dissection (CeAD) is a rare condition. One of the causes is the vascular type of Ehlers-Danlos syndrome (vEDS). A novel missense mutation in COL3A1 was found in a young patient with CeAD as the single manifestation of vEDS. This is a heterozygous c.953G > A mutation in exon 14, disrupting the normal Gly-X-Y repeats of type III procollagen, by converting glycine to aspartic acid. PMID:26497932

  19. Missense mutation of the EDA gene in a Jordanian family with X-linked hypohidrotic ectodermal dysplasia: phenotypic appearance and speech problems.

    PubMed

    Khabour, O F; Mesmar, F S; Al-Tamimi, F; Al-Batayneh, O B; Owais, A I

    2010-01-01

    Mutations in the EDA gene are responsible for X-linked hypohidrotic ectodermal dysplasia, the most common form of ectodermal dysplasia. Males show a severe form of this disease, while females often manifest mild to moderate symptoms. We identified a missense mutation (c.463C>T) in the EDA gene in a Jordanian family, using direct DNA sequencing. This mutation leads to an amino acid change of arginine to cysteine in the extracellular domain of ectodysplasin-A, a protein encoded by the EDA gene. The phenotype of a severely affected 11-year-old boy with this mutation included heat intolerance, sparse hair (hypotrichosis), absence of 17 teeth (oligodontia), speech problems, and damaged eccrine glands, resulting in reduced sweating (anhidrosis). Both the mother (40 years old) and the sister (10 years old) were carriers with mild to moderate symptoms of this disease, while the father was healthy. This detailed description of the phenotype caused by this missense mutation could be useful for prenatal diagnosis. PMID:20486090

  20. Non-Syndromic Tooth Agenesis in Two Chinese Families Associated with Novel Missense Mutations in the TNF Domain of EDA (Ectodysplasin A)

    PubMed Central

    Dong, Xiangbai; Wang, Zixing; Hu, Qingang; Chen, Meng; Hua, Zi-Chun

    2008-01-01

    Here we report two unrelated Chinese families with congenital missing teeth inherited in an X-linked manner. We mapped the affected locus to chromosome Xp11-Xq21 in one family. In the defined region, both families were found to have novel missense mutations in the ectodysplasin-A (EDA) gene. The mutation of c.947A>G caused the D316G substitution of the EDA protein. The mutation of c.1013C>T found in the other family resulted in the Thr to Met mutation at position 338 of EDA. The EDA gene has been reported responsible for X-linked hypohidrotic ectodermal dysplasia (XLHED) in humans characterized by impaired development of hair, eccrine sweat glands, and teeth. In contrast, all the affected individuals in the two families that we studied here had normal hair and skin. Structural analysis suggests that these two novel mutants may account for the milder phenotype by affecting the stability of EDA trimers. Our results indicate that these novel missense mutations in EDA are associated with the isolated tooth agenesis and provide preliminary explanation for the abnormal clinical phenotype at a molecular structural level. PMID:18545687

  1. High Incidence of Noonan Syndrome Features Including Short Stature and Pulmonic Stenosis in Patients carrying NF1 Missense Mutations Affecting p.Arg1809: Genotype-Phenotype Correlation.

    PubMed

    Rojnueangnit, Kitiwan; Xie, Jing; Gomes, Alicia; Sharp, Angela; Callens, Tom; Chen, Yunjia; Liu, Ying; Cochran, Meagan; Abbott, Mary-Alice; Atkin, Joan; Babovic-Vuksanovic, Dusica; Barnett, Christopher P; Crenshaw, Melissa; Bartholomew, Dennis W; Basel, Lina; Bellus, Gary; Ben-Shachar, Shay; Bialer, Martin G; Bick, David; Blumberg, Bruce; Cortes, Fanny; David, Karen L; Destree, Anne; Duat-Rodriguez, Anna; Earl, Dawn; Escobar, Luis; Eswara, Marthanda; Ezquieta, Begona; Frayling, Ian M; Frydman, Moshe; Gardner, Kathy; Gripp, Karen W; Hernández-Chico, Concepcion; Heyrman, Kurt; Ibrahim, Jennifer; Janssens, Sandra; Keena, Beth A; Llano-Rivas, Isabel; Leppig, Kathy; McDonald, Marie; Misra, Vinod K; Mulbury, Jennifer; Narayanan, Vinodh; Orenstein, Naama; Galvin-Parton, Patricia; Pedro, Helio; Pivnick, Eniko K; Powell, Cynthia M; Randolph, Linda; Raskin, Salmo; Rosell, Jordi; Rubin, Karol; Seashore, Margretta; Schaaf, Christian P; Scheuerle, Angela; Schultz, Meredith; Schorry, Elizabeth; Schnur, Rhonda; Siqveland, Elizabeth; Tkachuk, Amanda; Tonsgard, James; Upadhyaya, Meena; Verma, Ishwar C; Wallace, Stephanie; Williams, Charles; Zackai, Elaine; Zonana, Jonathan; Lazaro, Conxi; Claes, Kathleen; Korf, Bruce; Martin, Yolanda; Legius, Eric; Messiaen, Ludwine

    2015-11-01

    Neurofibromatosis type 1 (NF1) is one of the most frequent genetic disorders, affecting 1:3,000 worldwide. Identification of genotype-phenotype correlations is challenging because of the wide range clinical variability, the progressive nature of the disorder, and extreme diversity of the mutational spectrum. We report 136 individuals with a distinct phenotype carrying one of five different NF1 missense mutations affecting p.Arg1809. Patients presented with multiple café-au-lait macules (CALM) with or without freckling and Lisch nodules, but no externally visible plexiform neurofibromas or clear cutaneous neurofibromas were found. About 25% of the individuals had Noonan-like features. Pulmonic stenosis and short stature were significantly more prevalent compared with classic cohorts (P < 0.0001). Developmental delays and/or learning disabilities were reported in over 50% of patients. Melanocytes cultured from a CALM in a segmental NF1-patient showed two different somatic NF1 mutations, p.Arg1809Cys and a multi-exon deletion, providing genetic evidence that p.Arg1809Cys is a loss-of-function mutation in the melanocytes and causes a pigmentary phenotype. Constitutional missense mutations at p.Arg1809 affect 1.23% of unrelated NF1 probands in the UAB cohort, therefore this specific NF1 genotype-phenotype correlation will affect counseling and management of a significant number of patients. PMID:26178382

  2. Genetic and Molecular Analysis of the Soe1 Gene: A Trna(3)(glu) Missense Suppressor of Yeast Cdc8 Mutations

    PubMed Central

    Su, J. Y.; Belmont, L.; Sclafani, R. A.

    1990-01-01

    The CDC8 gene of Saccharomyces cerevisiae encodes deoxythymidylate (dTMP) kinase and is required for nuclear and mitochondrial DNA replication in both the mitotic and meiotic cell cycles. All cdc8 temperature-sensitive mutants are partially defective in meiotic and mitochondrial functions at the permissive temperature. In a study of revertants of temperature-sensitive cdc8 mutants, the SOE201 and SOE1 mutants were isolated. The SOE201 mutant is a disome of chromosome X to which the cdc8 gene maps. Using the chromosome X aneuploids to vary cdc8 gene dosage, we demonstrate that different levels of dTMP kinase activity are required for mitotic, meiotic or mitochondrial DNA replication. The SOE1 mutant contains a dominant suppressor that suppresses five different cdc8 alleles but does not suppress a complete cdc8 deletion. The SOE1 gene is located <1.5 cM from the CYH2 gene on chromosome VII and is adjacent to the TSM437-CYH2 region, with the gene order being SOE1-TSM437-CYH2. SOE1 is an inefficient suppressor that can neither suppress the cdc8 hypomorphic phenotype nor restore dTMP kinase activity in vitro. SOE1 is a single C to T mutation in the anticodon of a tRNA(3)(Glu) gene and thereby, produces a missense suppressor tRNA capable of recognizing AAA lysine codons. We propose that the resultant lysine to glutamate change stabilizes thermo-labile dTMP kinase molecules in the cell. PMID:2155851

  3. Missense mutations in Desmocollin-2 N-terminus, associated with arrhythmogenic right ventricular cardiomyopathy, affect intracellular localization of desmocollin-2 in vitro

    PubMed Central

    Beffagna, Giorgia; De Bortoli, Marzia; Nava, Andrea; Salamon, Michela; Lorenzon, Alessandra; Zaccolo, Manuela; Mancuso, Luisa; Sigalotti, Luca; Bauce, Barbara; Occhi, Gianluca; Basso, Cristina; Lanfranchi, Gerolamo; Towbin, Jeffrey A; Thiene, Gaetano; Danieli, Gian Antonio; Rampazzo, Alessandra

    2007-01-01

    Background Mutations in genes encoding desmosomal proteins have been reported to cause arrhythmogenic right ventricular cardiomyopathy (ARVC), an autosomal dominant disease characterised by progressive myocardial atrophy with fibro-fatty replacement. We screened 54 ARVC probands for mutations in desmocollin-2 (DSC2), the only desmocollin isoform expressed in cardiac tissue. Methods Mutation screening was performed by denaturing high-performance liquid chromatography and direct sequencing. To evaluate the pathogenic potentials of the DSC2 mutations detected in patients affected with ARVC, full-length wild-type and mutated cDNAs were cloned in eukaryotic expression vectors to obtain a fusion protein with green fluorescence protein (GFP); constructs were transfected in neonatal rat cardiomyocytes and in HL-1 cells. Results We identified two heterozygous mutations (c.304G>A (p.E102K) and c.1034T>C (p.I345T)) in two probands and in four family members. The two mutations p.E102K and p.I345T map to the N-terminal region, relevant to adhesive interactions. In vitro functional studies demonstrated that, unlike wild-type DSC2, the two N-terminal mutants are predominantly localised in the cytoplasm. Conclusion The two missense mutations in the N-terminal domain affect the normal localisation of DSC2, thus suggesting the potential pathogenic effect of the reported mutations. Identification of additional DSC2 mutations associated with ARVC may result in increased diagnostic accuracy with implications for genetic counseling. PMID:17963498

  4. Compound heterozygous hemophilia A in a female patient and the identification of a novel missense mutation, p.Met1093Ile.

    PubMed

    Qiao, Shu-Kai; Ren, Han-Yun; Ren, Jin-Hai; Guo, Xiao-Nan

    2014-02-01

    Hemophilia A (HA) in females is rare. Female HA cases are often misdiagnosed as acquired HA (AHA) or as von Willebrand disease type 2N (vWD-2N). Here, we report the case of a 37-year-old female HA patient with a moderate factor VIII (FVIII) deficiency. The patient had no personal or family history of bleeding disorders, but presented with heavy uterine bleeding following surgery to remove an intrauterine device. IgG inhibitory antibodies against FVIII were undetected. A compound heterozygote mutation of the FVIII gene (F8) was found in this patient. The p.Val502Asp mutation, which has been reported previously, affects A2 domain function. A novel missense point mutation, p.Met1093Ile, was identified in the B domain. The compound heterozygote mutations in F8, p.Val502Asp and p.Met1093Ile, caused HA in this female patient, with a moderate phenotype. PMID:24317041

  5. Compound heterozygous hemophilia A in a female patient and the identification of a novel missense mutation, p.Met1093Ile

    PubMed Central

    QIAO, SHU-KAI; REN, HAN-YUN; REN, JIN-HAI; GUO, XIAO-NAN

    2014-01-01

    Hemophilia A (HA) in females is rare. Female HA cases are often misdiagnosed as acquired HA (AHA) or as von Willebrand disease type 2N (vWD-2N). Here, we report the case of a 37-year-old female HA patient with a moderate factor VIII (FVIII) deficiency. The patient had no personal or family history of bleeding disorders, but presented with heavy uterine bleeding following surgery to remove an intrauterine device. IgG inhibitory antibodies against FVIII were undetected. A compound heterozygote mutation of the FVIII gene (F8) was found in this patient. The p.Val502Asp mutation, which has been reported previously, affects A2 domain function. A novel missense point mutation, p.Met1093Ile, was identified in the B domain. The compound heterozygote mutations in F8, p.Val502Asp and p.Met1093Ile, caused HA in this female patient, with a moderate phenotype. PMID:24317041

  6. A novel missense mutation in CACNA1A evaluated by in silico protein modeling is associated with non-episodic spinocerebellar ataxia with slow progression.

    PubMed

    Bürk, Katrin; Kaiser, Frank J; Tennstedt, Stephanie; Schöls, Ludger; Kreuz, Friedmar R; Wieland, Thomas; Strom, Tim M; Büttner, Thomas; Hollstein, Ronja; Braunholz, Diana; Plaschke, Jens; Gillessen-Kaesbach, Gabriele; Zühlke, Christine

    2014-04-01

    Spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2) and familial hemiplegic migraine type 1 (FHM1) are allelic disorders of the gene CACNA1A encoding the P/Q subunit of a voltage gated calcium channel. While SCA6 is related to repeat expansions affecting the C-terminal part of the protein, EA2 and FHM phenotypes are usually associated with nonsense and missense mutations leading to impaired channel properties. In three unrelated families with dominant cerebellar ataxia, symptoms cosegregated with CACNA1A missense mutations of evolutionary highly conserved amino acids (exchanges p.E668K, p.R583Q and p.D302N). To evaluate pathogenic effects, in silico, protein modeling analyses were performed which indicate structural alterations of the novel mutation p.E668K within the homologous domain 2 affecting CACNA1A protein function. The phenotype is characterised by a very slowly progressive ataxia, while ataxic episodes or migraine are uncommon. These findings enlarge the phenotypic spectrum of CACNA1A mutations. PMID:24486772

  7. A Missense Mutation in the Alpha-Actinin 1 Gene (ACTN1) Is the Cause of Autosomal Dominant Macrothrombocytopenia in a Large French Family

    PubMed Central

    Guéguen, Paul; Rouault, Karen; Chen, Jian-Min; Raguénès, Odile; Fichou, Yann; Hardy, Elisabeth; Gobin, Eric; Pan-petesch, Brigitte; Kerbiriou, Mathieu; Trouvé, Pascal; Marcorelles, Pascale; Abgrall, Jean-francois; Le Maréchal, Cédric; Férec, Claude

    2013-01-01

    Inherited thrombocytopenia is a heterogeneous group of disorders characterized by a reduced number of blood platelets. Despite the identification of nearly 20 causative genes in the past decade, approximately half of all subjects with inherited thrombocytopenia still remain unexplained in terms of the underlying pathogenic mechanisms. Here we report a six-generation French pedigree with an autosomal dominant mode of inheritance and the identification of its genetic basis. Of the 55 subjects available for analysis, 26 were diagnosed with isolated macrothrombocytopenia. Genome-wide linkage analysis mapped a 10.9 Mb locus to chromosome 14 (14q22) with a LOD score of 7.6. Candidate gene analysis complemented by targeted next-generation sequencing identified a missense mutation (c.137GA; p.Arg46Gln) in the alpha-actinin 1 gene (ACTN1) that segregated with macrothrombocytopenia in this large pedigree. The missense mutation occurred within actin-binding domain of alpha-actinin 1, a functionally critical domain that crosslinks actin filaments into bundles. The evaluation of cultured mutation-harboring megakaryocytes by electron microscopy and the immunofluorescence examination of transfected COS-7 cells suggested that the mutation causes disorganization of the cellular cytoplasm. Our study concurred with a recently published whole-exome sequence analysis of six small Japanese families with congenital macrothrombocytopenia, adding ACTN1 to the growing list of thrombocytopenia genes. PMID:24069336

  8. Variants of the D{sub 5} dopamine receptor gene found in patients with schizophrenia: Identification of a nonsense mutation and multiple missense changes

    SciTech Connect

    Sobell, J.L.; Lind, T.J.; Sommer, S.S.

    1994-09-01

    To determine whether mutations in the D{sub 5} dopamine receptor (D{sub 5}DR) gene are associated with schizophrenia, the gene was examined in 78 unrelated schizophrenic individuals. After amplification by the polymerase chain reaction, products were examined by dideoxy fingerprinting (ddF), a highly sensitive screening method related to single strand conformational polymorphism analysis. All samples with unusual ddF patterns were sequenced to precisely identify the sequence change. In the 156 D{sub 5}DR alleles examined, nine sequence changes were identified. Four of the nine did not affect protein structure; of these, three were silent changes and one was a transition in the 3{prime} untranslated region. The remaining five sequence changes result in protein alterations: of these, one is a missense change in a non-conserved amino acid, 3 are missense changes in amino acids that are conserved in some dopamine D{sub 5} receptors and the last is a nonsense mutation. To investigate whether the nonsense mutation was associated with schizophrenia, 400 additional schizophrenic cases of western European descent and 1914 ethnically-similar controls were screened for the change. One additional schizophrenic carrier was identified and verified by direct genomic sequencing (allele frequency: .0013), but eight carriers also were found and confirmed among the non-schizophrenics (allele frequency: .0021)(p>.25). The gene was re-examined in all newly identified carriers of the nonsense mutation by direct sequencing and/or ddF in search of additional mutations. None were identified. Family studies also were conducted to investigate possible cosegregation of the mutation with other neuropsychiatric diseases, but this was not demonstrated. Thus, the mutation does not appear to be associated with an increased risk of schizophrenia nor does an initial analysis suggest cosegregation with other neuropsychiatric disorders or symptom complexes.

  9. Contribution of novel ATGL missense mutations to the clinical phenotype of NLSD-M: a strikingly low amount of lipase activity may preserve cardiac function

    PubMed Central

    Tavian, Daniela; Missaglia, Sara; Redaelli, Chiara; Pennisi, Elena M.; Invernici, Gloria; Wessalowski, Ruediger; Maiwald, Robert; Arca, Marcello; Coleman, Rosalind A.

    2012-01-01

    The lack of adipose triglyceride lipase (ATGL), a patatin-like phospholipase domain-containing enzyme that hydrolyzes fatty acids from triacylglycerol (TAG) stored in multiple tissues, causes the autosomal recessive disorder neutral lipid storage disease with myopathy (NLSD-M). In two families of Lebanese and Italian origin presenting with NLSD-M, we identified two new missense mutations in highly conserved regions of ATGL (p.Arg221Pro and p.Asn172Lys) and a novel nonsense mutation (p.Trp8X). The Lebanese patients harbor homozygous p.Arg221Pro, whereas the Italian patients are heterozygotes for p.Asn172Lys and the p.Trp8X mutation. The p.Trp8X mutation results in a complete absence of ATGL protein, while the p.Arg221Pro and p.Asn172Lys mutations result in proteins with minimal lipolytic activity. Although these mutations did not affect putative catalytic residues or the lipid droplet (LD)-binding domain of ATGL, cytosolic LDs accumulated in cultured skin fibroblasts from the patients. The missense mutations might destabilize a random coil (p.Asn172Lys) or a helix (p.Arg221Pro) structure within or proximal to the patatin domain of the lipase, thereby interfering with the enzyme activity, while leaving intact the residues required to localize the protein to LDs. Overexpressing wild-type ATGL in one patient's fibroblasts corrected the metabolic defect and effectively reduced the number and area of cellular LDs. Despite the poor lipase activity in vitro, the Lebanese siblings have a mild myopathy and not clinically evident myocardial dysfunction. The patients of Italian origin show a late-onset and slowly progressive skeletal myopathy. These findings suggest that a small amount of correctly localized lipase activity preserves cardiac function in NLSD-M. PMID:22990388

  10. Mutations in the X-linked E{sub 1}{alpha} subunit of pyruvate dehydrogenase: Exon skipping, insertion of duplicate sequence, and missense mutations leading to the deficiency of the pyruvate dehydrogenase complex

    SciTech Connect

    Chun, K.; Mackay, N.; Petrova-Benedict, P.; Robinson, B.H.; Federico, A.; Fois, A.; Cole, D.E.C.; Robertson, E.

    1995-03-01

    Human pyruvate dehydrogenase (PDH)-complex deficiency is an inborn error of metabolism that is extremely heterogeneous in its presentation and clinical course. In a study of 14 patients (7 females and 7 males), we have found a mutation in the coding region of the E{sub 1}{alpha} gene in all 14 patients. Two female patients had the same 7-bp deletion at nt 927; another female patient had a 3-bp deletion at nt 931. Another female patient was found to have a deletion of exon 6 in her cDNA. Two other female patients were found to have insertions, one of 13 bp at nt 981 and one of 46 bp at nucleotide 1078. Two male patients were found to have a 4-bp insertion at nucleotide 1163. The remaining six patients all had missense mutations. A male patient and a female patient both had an A1133G mutation. The other missense mutations were C214T, C615A, and C787G (two patients). Five of these mutations are novel mutations, five had been previously reported in other patients, and two were published observations in other patients in an E{sub 1}{alpha}-mutation summary. In the four cases where parent DNA was available, only one mother was found to be a carrier of the same mutation as her child. 61 refs., 5 figs., 2 tabs.

  11. A novel missense mutation in the NDP gene in a child with Norrie disease and severe neurological involvement including infantile spasms.

    PubMed

    Lev, Dorit; Weigl, Yuval; Hasan, Mariana; Gak, Eva; Davidovich, Michael; Vinkler, Chana; Leshinsky-Silver, Esther; Lerman-Sagie, Tally; Watemberg, Nathan

    2007-05-01

    Norrie disease (ND) is a rare X-linked recessive disorder characterized by congenital blindness and in some cases, mental retardation and deafness. Other neurological complications, particularly epilepsy, are rare. We report on a novel mutation identified in a patient with ND and profound mental retardation. The patient was diagnosed at the age of 6 months due to congenital blindness. At the age of 8 months he developed infantile spasms, which were diagnosed at 11 months as his EEG demonstrated hypsarrhythmia. Mutation analysis of the ND gene (NDP) of the affected child and his mother revealed a novel missense mutation at position c.134T > A resulting in amino acid change at codon V45E. To the best of our knowledge, such severe neurological involvement has not been previously reported in ND patients. The severity of the phenotype may suggest the functional importance of this site of the NDP gene. PMID:17334993

  12. Identification of a Novel Heterozygous Missense Mutation in the CACNA1F Gene in a Chinese Family with Retinitis Pigmentosa by Next Generation Sequencing

    PubMed Central

    Tania, Mousumi; Wang, Hui; Khan, Md. Asaduzzaman; Duan, Chengxia; Zhu, Li; Chen, Rui; Lv, Hongbin

    2015-01-01

    Background. Retinitis pigmentosa (RP) is an inherited retinal degenerative disease, which is clinically and genetically heterogeneous, and the inheritance pattern is complex. In this study, we have intended to study the possible association of certain genes with X-linked RP (XLRP) in a Chinese family. Methods. A Chinese family with RP was recruited, and a total of seven individuals were enrolled in this genetic study. Genomic DNA was isolated from peripheral leukocytes, and used for the next generation sequencing (NGS). Results. The affected individual presented the clinical signs of XLRP. A heterozygous missense mutation (c.1555C>T, p.R519W) was identified by NGS in exon 13 of the CACNA1F gene on X chromosome, and was confirmed by Sanger sequencing. It showed perfect cosegregation with the disease in the family. The mutation at this position in the CACNA1F gene of RP was found novel by database searching. Conclusion. By using NGS, we have found a novel heterozygous missense mutation (c.1555C>T, p.R519W) in CACNA1F gene, which is probably associated with XLRP. The findings might provide new insights into the cause and diagnosis of RP, and have implications for genetic counseling and clinical management in this family. PMID:26075273

  13. A novel rasopathy caused by recurrent de novo missense mutations in PPP1CB closely resembles Noonan syndrome with loose anagen hair.

    PubMed

    Gripp, Karen W; Aldinger, Kimberly A; Bennett, James T; Baker, Laura; Tusi, Jessica; Powell-Hamilton, Nina; Stabley, Deborah; Sol-Church, Katia; Timms, Andrew E; Dobyns, William B

    2016-09-01

    Noonan syndrome is a rasopathy caused by mutations in multiple genes encoding components of the RAS/MAPK pathway. Despite its variable phenotype, limited genotype-phenotype correlations exist. Noonan syndrome with loose anagen hair (NS-LAH) is characterized by its distinctive hair anomalies, developmental differences, and structural brain abnormalities and is caused by a single recurrent missense SHOC2 mutation. SHOC2 forms a complex with protein phosphatase 1 (PP1C). Protein phosphatases counterbalance kinases and control activation of signaling proteins, such as the mitogen-activated protein kinases of the RAS/MAPK pathway. Here we report four patients with de novo missense mutations in protein phosphatase one catalytic subunit beta (PPP1CB), sharing a recognizable phenotype. Three individuals had the recurrent PPP1CB c.146G>C, p.Pro49Arg mutation, the fourth had a c.166G>C, p.Ala56Pro change. All had relative or absolute macrocephaly, low-set and posteriorly angulated ears, and developmental delay. Slow growing and/or sparse hair and/or an unruly hair texture was present in all. Three individuals had feeding difficulties requiring feeding tubes. One of two males had cryptorchidism, another had pectus excavatum. Short stature was present in three. A female with the recurrent mutation had a Dandy-Walker malformation and optic nerve hypoplasia. Mild ventriculomegaly occurred in all, cerebellar tonsillar ectopia was seen in two and progressed to Chiari 1 malformation in one individual. Based on the combination of phenotypic findings and PPP1CB's effect on RAF dephosphorylation within the RAS/MAPK pathway, this novel condition can be considered a rasopathy, most similar to NS-LAH. Collectively, these mutations meet the standardized criteria for pathogenicity. © 2016 Wiley Periodicals, Inc. PMID:27264673

  14. Molecular basis of recessive congenital methemoglobinemia, types I and II: Exon skipping and three novel missense mutations in the NADH-cytochrome b5 reductase (diaphorase 1) gene.

    PubMed

    Kugler, W; Pekrun, A; Laspe, P; Erdlenbruch, B; Lakomek, M

    2001-04-01

    Hereditary methemoglobinemia due to reduced nicotin amide adenine dinucleotide (NADH)-cytochrome b5 reductase (b5r) deficiency is classified into an erythrocyte type (I) and a generalized type (II). We investigated the b5r gene of three unrelated patients with types I and II and found four novel mutations. The patient with type I was homozygous for a c.535 G-->A exchange in exon 6 (A179T). The patients with type II were found to be homozygous for a c.757 G-->A transition in exon 9 (V253M) and compound heterozygous for two mutations, respectively. One allele presented a c.379 A-->G transition (M127V). The second allele carried a sequence difference at the invariant 3' splice-acceptor dinucleotide of intron 4 (IVS4-2A-->G) resulting in skipping of exon 5. To characterize a possible effect of this mutation on RNA metabolism, poly(A)(+) RNA was analyzed by RT-PCR and sequencing. The results show that RNA is made from the allele harboring the 3'-splice site mutation. Furthermore, western blot analysis revealed a complete absence of immunologically detectable b5r in skin fibroblasts of this patient. The compound heterozygosity for the splice site and the missense mutations apparently caused hereditary methemoglobinemia type II in this patient. Hum Mutat 17:348, 2001. PMID:11295830

  15. Novel X-linked glomerulopathy is associated with a COL4A5 missense mutation in a non-collagenous interruption.

    PubMed

    Becknell, Brian; Zender, Gloria A; Houston, Ronald; Baker, Peter B; McBride, Kim L; Luo, Wentian; Hains, David S; Borza, Dorin-Bogdan; Schwaderer, Andrew L

    2011-01-01

    A novel COL4A5 mutation causes rapid progression to end-stage renal disease in males, despite the absence of clinical and biopsy findings associated with Alport syndrome. Affected males have proteinuria, variable hematuria, and an early progression to end-stage renal disease. Renal biopsy findings include global and segmental glomerulosclerosis, mesangial hypercellularity and basement membrane immune complex deposition. Exon sequencing of the COL4A5 locus identified a thymine to guanine transversion at nucleotide 665, resulting in a phenylalanine to cysteine missense mutation at codon 222. The phenylalanine at position 222 is absolutely conserved among vertebrates. This mutation was confirmed in 4 affected males and 4 female obligate carriers, but was absent in 6 asymptomatic male family members and 198 unrelated individuals. Immunostaining for α5(IV) collagen in renal biopsies from affected males was normal. This mutation, in a non-collagenous interruption associated with severe renal disease, provides evidence for the importance of this structural motif and suggests the range of phenotypes associated with COL4A5 mutations is more diverse than previously realized. Hence, COL4A5 mutation analysis should be considered when glomerulonephritis presents in an X-linked inheritance pattern, even with a presentation distinct from Alport syndrome. PMID:20881942

  16. Human glucokinase gene: isolation, characterization, and identification of two missense mutations linked to early-onset non-insulin-dependent (type 2) diabetes mellitus.

    PubMed Central

    Stoffel, M; Froguel, P; Takeda, J; Zouali, H; Vionnet, N; Nishi, S; Weber, I T; Harrison, R W; Pilkis, S J; Lesage, S

    1992-01-01

    DNA polymorphisms in the glucokinase gene have recently been shown to be tightly linked to early-onset non-insulin-dependent diabetes mellitus in approximately 80% of French families with this form of diabetes. We previously identified a nonsense mutation in exon 7 in one of these families and showed that it was the likely cause of glucose intolerance in this dominantly inherited disorder. Here we report the isolation and partial sequence of the human glucokinase gene and the identification of two missense mutations in exon 7, Thr-228----Met and Gly-261----Arg, that cosegregate with early-onset non-insulin-dependent diabetes mellitus. To assess the molecular mechanism by which mutations at these two sites may affect glucokinase activity, the crystal structure of the related yeast hexokinase B was used as a simple model for human beta-cell glucokinase. Computer-assisted modeling suggests that mutation of Thr-228 affects affinity for ATP and mutation of Gly-261 may alter glucose binding. The identification of mutations in glucokinase, a protein that plays an important role in hepatic and beta-cell glucose metabolism, indicates that early-onset non-insulin-dependent diabetes mellitus may be primarily a disorder of carbohydrate metabolism. Images PMID:1502186

  17. A Novel Missense Mutation in the Second Extracellular Domain of GJB2, p.Ser183Phe, Causes a Syndrome of Focal Palmoplantar Keratoderma with Deafness

    PubMed Central

    de Zwart-Storm, Eugene A.; van Geel, Michel; van Neer, Pierre A.F.A.; Steijlen, Peter M.; Martin, Patricia E.; van Steensel, Maurice A.M.

    2008-01-01

    Gap junctions, which consist of connexins, are intercellular channels that mediate rapid intercellular communication. In the skin, connexins are involved in the regulation of epidermal growth and differentiation. GJB2 encodes connexin26, which is an important skin-expressed gap junction protein. Mutations in GJB2 cause a wide variety of unique disorders, but despite extensive research, their mechanisms of action are poorly understood. The identification of novel diseases caused by mutations in GJB2 may help to illuminate the genotype-phenotype correlation and elucidate the function of different regions of the protein. Here, we report the first account of a family with a GJB2 missense mutation in the second extracellular domain (p.Ser183Phe) that causes skin abnormalities in addition to sensorineural hearing loss. Using fluorescent connexin26-EGFP fusion proteins, we showed that the mutation induces a partial protein transport defect that cannot be rescued by wild-type protein. Dye-transfer experiments using a parachute assay revealed channel functionality. Although p.Ser183Phe affects the second extracellular domain, mutations in the first extracellular domain also lead to focal palmoplantar keratoderma and likewise perturb protein transport in a dominant-negative manner. Therefore, we hypothesize that focal palmoplantar keratoderma in gap junction skin disease may be specifically associated with connexin trafficking defects as well as with mutations affecting its extracellular domains, thus broadening the spectrum of GJB2-associated diseases. PMID:18787097

  18. Hepatic Fibrinogen Storage Disease in a Patient with Hypofibrinogenemia: Report of a Case with a Missense Mutation of the FGA Gene.

    PubMed

    Lee, Michael J; Venick, Robert; Bhuta, Sunita; Li, Xinmin; Wang, Hanlin L

    2015-11-01

    We report a 9-year-old patient with abnormal liver tests found incidentally during routine bloodwork as part of a preoperative evaluation for excision of a benign cyst. A liver biopsy demonstrated hepatocytes to have pale and expanded cytoplasm that contained multiple vague globular eosinophilic inclusions. Electron microscopy showed fingerprint-like structures in the dilated cisternae of the rough endoplasmic reticulum, characteristic of fibrinogen. Whole exome sequencing identified a heterozygous missense mutation at codon 35 of the fibrinogen α (FGA) gene. No mutation was identified in the β or γ chains. His plasma fibrinogen levels were found to be decreased to 85 mg/dL (normal range 215-464). His family history was pertinent for his mother and maternal grandfather with hypofibrinogenemia. He had not had any significant bleeding episodes except for minor bruising over the shins. This case illustrates a rare etiology of storage disease that causes abnormal liver function tests. PMID:26676819

  19. Autosomal dominant epilepsy with febrile seizures plus with missense mutations of the (Na+)-channel alpha 1 subunit gene, SCN1A.

    PubMed

    Ito, M; Nagafuji, H; Okazawa, H; Yamakawa, K; Sugawara, T; Mazaki-Miyazaki, E; Hirose, S; Fukuma, G; Mitsudome, A; Wada, K; Kaneko, S

    2002-01-01

    Evidence that febrile seizures have a strong genetic predisposition has been well documented. In families of probands with multiple febrile convulsions, an autosomal dominant inheritance with reduced penetrance is suspected. Four candidate loci for febrile seizures have been suggested to date; FEB1 on 8q13-q21, FEB2 on 19p, FEB3 on 2q23-q24, and FEB4 on 5q14-15. A missense mutation was identified in the voltage-gated sodium (Na(+))-channel beta 1 subunit gene, SCN1B at chromosome 19p13.1 in generalized epilepsy with the febrile seizures plus type 1 (GEFS+1) family. Several missense mutations of the (Na(+))-channel alpha 1 subunit (Nav1.1) gene, SCN1A were also identified in GEFS+2 families at chromosome 2q23-q24.3. The aim of this report is precisely to describe the phenotypes of Japanese patients with novel SCN1A mutations and to reevaluate the entity of GEFS+. Four family members over three generations and one isolated (phenotypically sporadic) case with SCN1A mutations were clinically investigated. The common seizure type in these patients was febrile and afebrile generalized tonic-clonic seizures (FS+). In addition to FS+, partial epilepsy phenotypes were suspected in all affected family members and electroencephalographically confirmed in three patients of two families. GEFS+ is genetically and clinically heterogeneous, and associated with generalized epilepsy and partial epilepsy as well. The spectrum of GEFS+ should be expanded to include partial epilepsies and better to be termed autosomal dominant epilepsy with febrile seizures plus (ADEFS+). PMID:11823106

  20. The combination of new missense mutation with [A(TA)7TAA] dinucleotide repeat in UGT1A1 gene promoter causes Gilbert's syndrome.

    PubMed

    D'Angelo, Rosalia; Rinaldi, Carmela; Donato, Luigi; Nicocia, Giacomo; Sidoti, Antonina

    2015-01-01

    Gilbert's syndrome is a benign form of unconjugated hyperbilirubinemia caused by reduction of hepatic activity of bilirubin glucuronosyltranferase. The most common genotype of Gilbert's syndrome is the homozygous polymorphism [A(TA)7TAA] in the promoter of the gene for UDP-glucuronosyltransferase 1A1 (UGT1A1), which results in a decrease in UGT1A1 activity. However, individuals with normal bilirubin levels and no clinical symptoms of Gilbert's syndrome may also present this in a homozygous condition. By direct sequencing, we performed UGT1A1 gene analysis on a 31-year-old man with Gilbert's syndrome and homozygous for [A(TA)7TAA], and on his parents. Two UGT1A1 mutations were identified. Both mutations were inherited from each of the two parents, both with normal levels of bilirubin. One of the two mutations, c.993 (p.Q331H), is a missense mutation and is predicted to have a deleterious effect on protein functionality. Given the importance for clinicians to consider the Gilbert genotype in cases with unexplained indirect hyperbilirubinemia, the case we report may add a new variant to the spectrum of mutations of Gilbert's syndrome. PMID:25887876

  1. A missense mutation (1278T) in the cystathionine {beta}-synthase gene prevalent in pyridoxine-responsive homocystinuria and associated with mild clinical phenotype

    SciTech Connect

    Shih, V.E.; Fringer, J.M.; Mandell, R.

    1995-07-01

    Cystathionine {beta}-synthase (CBS) deficiency is an autosomal recessive disorder characterized by homocystinuria and multisystem clinical disease. Patients responsive to pyridoxine usually have a milder clinical phenotype than do nonresponsive patients, and we studied the molecular pathology of this disorder in an attempt to understand the molecular basis of the clinical variation. We previously reported a T833C transition in exon 8 causing a substitution of threonine for isoleucine at codon 278 (I278T). By PCR amplification and sequencing of exon 8 from genomic DNA we have now detected the I278T mutation in 7 of 11 patients with in vivo pyridoxine responsiveness and 0 of 27 pyridoxine-nonresponsive patients. Two pyridoxine-responsive patients are homozygous and five are heterozygous for I278T. We have now observed the I278T mutation in 41% (9 of 22) of the independent alleles in pyridoxine-responsive patients of varied ethnic backgrounds. In two of the compound heterozygotes we identified a novel mutation (G139R and E144K) in the other allele. The finding that the two patients who are homozygous for I278T have only ectopia lentis and mild bone demineralization suggests that this mutation is associated with both in vivo pyridoxine responsiveness and mild clinical disease. Compound heterozygous patients who have one copy of this missense mutation are likely to retain some degree of pyridoxine responsiveness. 14 refs., 4 figs., 1 tab.

  2. Structural Effects of Some Relevant Missense Mutations on the MECP2-DNA Binding: A MD Study Analyzed by Rescore+, a Versatile Rescoring Tool of the VEGA ZZ Program.

    PubMed

    Pedretti, Alessandro; Granito, Cinzia; Mazzolari, Angelica; Vistoli, Giulio

    2016-09-01

    DNA methylation plays key roles in mammalian cells and is modulated by a set of proteins which recognize symmetrically methylated nucleotides. Among them, the protein MECP2 shows multifunctional roles repressing and/or activating genes by binding to both methylated and unmethylated regions of the genome. The interest for this protein markedly increased from the observation that its mutations are the primary cause of Rett syndrome, a neurodevelopmental disorder which causes mental retardation in young females. Thus, the present study is aimed to investigate the effects of some of these known pathogenic missense mutations (i.e. R106Q, R106W, R111G, R133C and R133H) on the MECP2 folding and DNA binding by molecular dynamics simulations. The effects of the simulated mutations are also parameterized by using a here proposed new tool, named Rescore+, implemented in the VEGA ZZ suite of programs, which calculates a set of scoring functions on all frames of a trajectory or on all complexes contained in a database thus allowing an easy rescoring of results coming from MD or docking simulations. The obtained results revealed that the reported loss of the MECP2 function induced by the simulated mutations can be ascribed to both stabilizing and destabilizing effect on DNA binding. The study confirms that MD simulations are particularly useful to rationalize and predict the mutation effects offering insightful information for diagnostics and drug design. PMID:27546046

  3. A Missense Mutation of the Gene Encoding Synaptic Vesicle Glycoprotein 2A (SV2A) Confers Seizure Susceptibility by Disrupting Amygdalar Synaptic GABA Release.

    PubMed

    Tokudome, Kentaro; Okumura, Takahiro; Terada, Ryo; Shimizu, Saki; Kunisawa, Naofumi; Mashimo, Tomoji; Serikawa, Tadao; Sasa, Masashi; Ohno, Yukihiro

    2016-01-01

    Synaptic vesicle glycoprotein 2A (SV2A) is specifically expressed in the membranes of synaptic vesicles and modulates action potential-dependent neurotransmitter release. To explore the role of SV2A in the pathogenesis of epileptic disorders, we recently generated a novel rat model (Sv2a(L174Q) rat) carrying a missense mutation of the Sv2a gene and showed that the Sv2a(L174Q) rats were hypersensitive to kindling development (Tokudome et al., 2016). Here, we further conducted behavioral and neurochemical studies to clarify the pathophysiological mechanisms underlying the seizure vulnerability in Sv2a(L174Q) rats. Sv2a(L174Q) rats were highly susceptible to pentylenetetrazole (PTZ)-induced seizures, yielding a significantly higher seizure scores and seizure incidence than the control animals. Brain mapping analysis of Fos expression, a biological marker of neural excitation, revealed that the seizure threshold level of PTZ region-specifically elevated Fos expression in the amygdala in Sv2a(L174Q) rats. In vivo microdialysis study showed that the Sv2a(L174Q) mutation preferentially reduced high K(+) (depolarization)-evoked GABA release, but not glutamate release, in the amygdala. In addition, specific control of GABA release by SV2A was supported by its predominant expression in GABAergic neurons, which were co-stained with antibodies against SV2A and glutamate decarboxylase 1. The present results suggest that dysfunction of SV2A by the missense mutation elevates seizure susceptibility in rats by preferentially disrupting synaptic GABA release in the amygdala, illustrating the crucial role of amygdalar SV2A-GABAergic system in epileptogenesis. PMID:27471467

  4. A novel missense RAG-1 mutation results in T−B−NK+ SCID in Athabascan-speaking Dine Indians from the Canadian Northwest Territories

    PubMed Central

    Xiao, Zheng; Yannone, Steven M; Dunn, Elizabeth; Cowan, Morton J

    2009-01-01

    DNA double-strand repair factors in the non-homologous end joining (NHEJ) pathway resolve DNA double-strand breaks introduced by the recombination-activating gene (RAG) proteins during V(D)J recombination of T and B lymphocyte receptor genes. Defective NHEJ and subsequent failure of V(D)J recombination leads to severe combined immunodeficiency disease (SCID). We originally linked T−B−NK+ SCID in Athabascan-speaking Native Americans in the Southwestern US and Northwest Territories of Canada to chromosome 10. However, despite a common ancestry, the null mutation in the Artemis gene that we found to be causal in the SCID among the Navajo and Apache Indians was not present in the Dine Indians in the Northwest Territories. We now report a novel homozygous missense mutation (R776W) in RAG-1 in three children with T−B−NK+ SCID from two related families of Athabascan-speaking Dine Indians in the Canadian Northwest Territories. As expected, we found no increased sensitivity to ionizing radiation in patient fibroblasts. The impaired activity of this RAG-1 mutant in V(D)J recombination was confirmed by the EGFP-based V(D)J recombination assays. Overexpression of wild type RAG-1 in patient fibroblasts complemented V(D)J recombination, with recovery of both coding and signal joint formation. Our results indicate that the novel R776W missense mutation in RAG-1 is causal in the T−B−NK+ SCID phenotype in Athabascan-speaking Dine Indians from the Canadian Northwest Territories. PMID:18701881

  5. A Missense Mutation of the Gene Encoding Synaptic Vesicle Glycoprotein 2A (SV2A) Confers Seizure Susceptibility by Disrupting Amygdalar Synaptic GABA Release

    PubMed Central

    Tokudome, Kentaro; Okumura, Takahiro; Terada, Ryo; Shimizu, Saki; Kunisawa, Naofumi; Mashimo, Tomoji; Serikawa, Tadao; Sasa, Masashi; Ohno, Yukihiro

    2016-01-01

    Synaptic vesicle glycoprotein 2A (SV2A) is specifically expressed in the membranes of synaptic vesicles and modulates action potential-dependent neurotransmitter release. To explore the role of SV2A in the pathogenesis of epileptic disorders, we recently generated a novel rat model (Sv2aL174Q rat) carrying a missense mutation of the Sv2a gene and showed that the Sv2aL174Q rats were hypersensitive to kindling development (Tokudome et al., 2016). Here, we further conducted behavioral and neurochemical studies to clarify the pathophysiological mechanisms underlying the seizure vulnerability in Sv2aL174Q rats. Sv2aL174Q rats were highly susceptible to pentylenetetrazole (PTZ)-induced seizures, yielding a significantly higher seizure scores and seizure incidence than the control animals. Brain mapping analysis of Fos expression, a biological marker of neural excitation, revealed that the seizure threshold level of PTZ region-specifically elevated Fos expression in the amygdala in Sv2aL174Q rats. In vivo microdialysis study showed that the Sv2aL174Q mutation preferentially reduced high K+ (depolarization)-evoked GABA release, but not glutamate release, in the amygdala. In addition, specific control of GABA release by SV2A was supported by its predominant expression in GABAergic neurons, which were co-stained with antibodies against SV2A and glutamate decarboxylase 1. The present results suggest that dysfunction of SV2A by the missense mutation elevates seizure susceptibility in rats by preferentially disrupting synaptic GABA release in the amygdala, illustrating the crucial role of amygdalar SV2A-GABAergic system in epileptogenesis. PMID:27471467

  6. Novel ATRX gene damaging missense mutation c.6740A>C segregates with profound to severe intellectual deficiency without alpha thalassaemia

    PubMed Central

    Bouazzi, Habib; Thakur, Seema; Trujillo, Carlos; Alwasiyah, Mohammad Khalid; Munnich, Arnold

    2016-01-01

    Background & objectives: ATRX is a recessive X-linked intellectual deficiency (X-LID) gene causing predominately alpha-thalassaemia with a wide and clinically heterogeneous spectrum of intellectual deficiency syndromes. Although alpha-thalassaemia is commonly present, some patients do not express this sign despite the ATRX gene being altered. Most pathological mutations have been localized in two different major domains, the helicase and the plant homeo-domain (PHD)-like domain. In this study we examined a family of three males having an X-linked mental deficiency and developmental delay, and tried to establish a genetic diagnosis while discussing and comparing the phenotype of our patients to those reported in the literature. Methods: Three related males with intellectual deficiency underwent clinical investigations. We performed a karyotype analysis, CGH-array, linkage study, and X-exome sequencing in the index case to identify the genetic origin of this disorder. The X-inactivation study was carried out in the mother and Sanger sequencing was achieved in all family members to confirm the mutation. Results: A novel ATRX gene missense mutation (p.His2247Pro) was identified in a family of two uncles and their nephew manifesting intellectual deficiency and specific facial features without alpha-thalassaemia. The mutation was confirmed by Sanger sequencing. It segregated with the pathological phenotype. The mother and her two daughters were found to be heterozygous. Interpretation & conclusions: The novel mutation c.6740A>C was identified within the ATRX gene helicase domain and confirmed by Sanger sequencing in the three affected males as well as in the mother and her two daughters. This mutation was predicted to be damaging and deleterious. The novel mutation segregated with the phenotype without alpha-thalassaemia and with non-skewed X chromosome. PMID:26997013

  7. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems

    PubMed Central

    Zigler, J. Samuel; Hodgkinson, Colin A.; Wright, Megan; Klise, Andrew; Broman, Karl W.; Huang, Hao; Patek, Bonnie; Sergeev, Yuri; Hose, Stacey; Xaiodong, Jiao; Vasquez, David; Maragakis, Nicholas; Mori, Susumu; Goldman, David; Sinha, Debasish

    2016-01-01

    A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70–80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs

  8. A Spontaneous Missense Mutation in Branched Chain Keto Acid Dehydrogenase Kinase in the Rat Affects Both the Central and Peripheral Nervous Systems.

    PubMed

    Zigler, J Samuel; Hodgkinson, Colin A; Wright, Megan; Klise, Andrew; Sundin, Olof; Broman, Karl W; Hejtmancik, Fielding; Huang, Hao; Patek, Bonnie; Sergeev, Yuri; Hose, Stacey; Brayton, Cory; Xaiodong, Jiao; Vasquez, David; Maragakis, Nicholas; Mori, Susumu; Goldman, David; Hoke, Ahmet; Sinha, Debasish

    2016-01-01

    A novel mutation, causing a phenotype we named frogleg because its most obvious characteristic is a severe splaying of the hind limbs, arose spontaneously in a colony of Sprague-Dawley rats. Frogleg is a complex phenotype that includes abnormalities in hind limb function, reduced brain weight with dilated ventricles and infertility. Using micro-satellite markers spanning the entire rat genome, the mutation was mapped to a region of rat chromosome 1 between D1Rat131 and D1Rat287. Analysis of whole genome sequencing data within the linkage interval, identified a missense mutation in the branched-chain alpha-keto dehydrogenase kinase (Bckdk) gene. The protein encoded by Bckdk is an integral part of an enzyme complex located in the mitochondrial matrix of many tissues which regulates the levels of the branched-chain amino acids (BCAAs), leucine, isoleucine and valine. BCAAs are essential amino acids (not synthesized by the body), and circulating levels must be tightly regulated; levels that are too high or too low are both deleterious. BCKDK phosphorylates Ser293 of the E1α subunit of the BCKDH protein, which catalyzes the rate-limiting step in the catabolism of the BCAAs, inhibiting BCKDH and thereby, limiting breakdown of the BCAAs. In contrast, when Ser293 is not phosphorylated, BCKDH activity is unchecked and the levels of the BCAAs will decrease dramatically. The mutation is located within the kinase domain of Bckdk and is predicted to be damaging. Consistent with this, we show that in rats homozygous for the mutation, phosphorylation of BCKDH in the brain is markedly decreased relative to wild type or heterozygous littermates. Further, circulating levels of the BCAAs are reduced by 70-80% in animals homozygous for the mutation. The frogleg phenotype shares important characteristics with a previously described Bckdk knockout mouse and with human subjects with Bckdk mutations. In addition, we report novel data regarding peripheral neuropathy of the hind limbs

  9. A missense mutation in the PISA domain of HsSAS-6 causes autosomal recessive primary microcephaly in a large consanguineous Pakistani family.

    PubMed

    Khan, Muzammil A; Rupp, Verena M; Orpinell, Meritxell; Hussain, Muhammad S; Altmüller, Janine; Steinmetz, Michel O; Enzinger, Christian; Thiele, Holger; Höhne, Wolfgang; Nürnberg, Gudrun; Baig, Shahid M; Ansar, Muhammad; Nürnberg, Peter; Vincent, John B; Speicher, Michael R; Gönczy, Pierre; Windpassinger, Christian

    2014-11-15

    Asymmetric cell division is essential for normal human brain development. Mutations in several genes encoding centrosomal proteins that participate in accurate cell division have been reported to cause autosomal recessive primary microcephaly (MCPH). By homozygosity mapping including three affected individuals from a consanguineous MCPH family from Pakistan, we delineated a critical region of 18.53 Mb on Chromosome 1p21.3-1p13.1. This region contains the gene encoding HsSAS-6, a centrosomal protein primordial for seeding the formation of new centrioles during the cell cycle. Both next-generation and Sanger sequencing revealed a homozygous c.185T>C missense mutation in the HsSAS-6 gene, resulting in a p.Ile62Thr substitution within a highly conserved region of the PISA domain of HsSAS-6. This variant is neither present in any single-nucleotide polymorphism or exome sequencing databases nor in a Pakistani control cohort. Experiments in tissue culture cells revealed that the Ile62Thr mutant of HsSAS-6 is substantially less efficient than the wild-type protein in sustaining centriole formation. Together, our findings demonstrate a dramatic impact of the mutation p.Ile62Thr on HsSAS-6 function and add this component to the list of genes mutated in primary microcephaly. PMID:24951542

  10. A Missense Mutation in CLIC2 Associated with Intellectual Disability is Predicted by In Silico Modeling to Affect Protein Stability and Dynamics

    PubMed Central

    Witham, Shawn; Takano, Kyoko; Schwartz, Charles; Alexov, Emil

    2011-01-01

    Large-scale next generation resequencing of X chromosome genes identified a missense mutation in the CLIC2 gene on Xq28 in a male with X-linked intellectual disability (XLID) and not found in healthy individuals. At the same time, numerous nsSNPs (nonsynonomous SNP) have been reported in the CLIC2 gene in healthy individuals indicating that the CLIC2 protein can tolerate amino acid substitutions and be fully functional. To test the possibility that p.H101Q is a disease-causing mutation, we performed in silico simulations to calculate the effects of the p.H101Q mutation on CLIC2 stability, dynamics and ionization states while comparing the effects obtained for presumably harmless nsSNPs. It was found that p.H101Q, in contrast with other nsSNPs, (a) lessens the flexibility of the joint loop which is important for the normal function of CLIC2, (b) makes the overall 3D structure of CLIC2 more stable and thus reduces the possibility of the large conformational change expected to occur when CLIC2 moves from a soluble to membrane form and (c) removes the positively charged residue, H101, which may be important for the membrane association of CLIC2. The results of in silico modeling, in conjunction with the polymorphism analysis, suggest that p.H101Q may be a disease-causing mutation, the first one suggested in the CLIC family. PMID:21630357

  11. Structure of the human glucokinase gene and identification of a missense mutation in a Japanese patient with early-onset non-insulin-dependent diabetes mellitus

    SciTech Connect

    Sakura, Hiroshi; Eto, Kazuhiro; Ueno, Hirohisa; Yazaki, Yoshio; Kadowaki, Takashi ); Kadowaki, Hiroko; Simokawa, Kotaro; Akanuma, Yasuo ); Koda, Naoya; Fukushima, Yoshimitsu )

    1992-12-01

    Glucokinase is thought to play a glucose-sensor role in the pancreas, and abnormalities in its structure, function, and regulation can induce diabetes. The authors isolated the human glucokinase gene, and determined its genomic structure including exon-intron boundaries. Structure of the glucokinase gene in human was very similar to that in rat. Then, by screening Japanese diabetic patients using polymerase chain reaction - single strand conformation polymorphism (PCR-SSCP) and direct-sequencing strategies, they identified a missense mutation substituting ariginine (AGG) for glycine (GGG) at position 261 in exon 7 of the glucokinase gene in a patient with early-onset non-insulin-dependent diabetes (NIDDM). 12 refs., 3 figs., 2 tabs.

  12. Association of missense mutations in epoxyalkane coenzyme M transferase with adaptation of Mycobacterium sp. strain JS623 to growth on vinyl chloride.

    PubMed

    Jin, Yang Oh; Cheung, Samantha; Coleman, Nicholas V; Mattes, Timothy E

    2010-06-01

    Vinyl chloride (VC) is a toxic groundwater pollutant associated with plastic manufacture and chlorinated solvent use. Aerobic bacteria that grow on VC as a carbon and energy source can evolve in the laboratory from bacteria that grow on ethene, but the genetic changes involved are unknown. We investigated VC adaptation in two variants (JS623-E and JS623-T) of the ethene-oxidizing Mycobacterium strain JS623. Missense mutations in the EtnE gene developed at two positions (W243 and R257) in cultures exposed to VC but not in cultures maintained on ethene. Epoxyalkane-coenzyme M transferase (EaCoMT) activities in cell extracts of JS623-E and JS623-T (150 and 645 nmol/min/mg protein, respectively) were higher than that of wild-type JS623 (74 nmol/min/mg protein), and in both variant cultures epoxyethane no longer accumulated during growth on ethene. The heterologous expression of two variant etnE alleles (W243G [etnE1] and R257L [etnE2]) from strain JS623 in Mycobacterium smegmatis showed that they had 42 to 59% higher activities than the wild type. Recombinant JS623 cultures containing mutant EtnE genes cloned in the vector pMV261 adapted to growth on VC more rapidly than the wild-type JS623 strain, with incubation times of 60 days (wild type), 1 day (pMVetnE1), and 35 days (pMVetnE2). The JS623(pMVetnE) culture did not adapt to VC after more than 60 days of incubation. Adaptation to VC in strain JS623 is consistently associated with two particular missense mutations in the etnE gene that lead to higher EaCoMT activity. This is the first report to pinpoint a genetic change associated with the transition from cometabolic to growth-linked VC oxidation in bacteria. PMID:20363787

  13. A novel missense KIT mutation causing piebaldism in one Chinese family associated with café-au-lait macules and intertriginous freckling

    PubMed Central

    Jia, Wei-Xue; Xiao, Xue-Min; Wu, Jian-Bing; Ma, Yi-Ping; Ge, Yi-Ping; Li, Qi; Mao, Qiu-Xia; Li, Cheng-Rang

    2015-01-01

    Piebaldism is a rare autosomal dominant genodermatosis, manifesting as congenital and stable depigmentation of the skin and white forelock. It has been found to be associated with mutations in the KIT or SLUG genes. We report a Chinese piebaldism family including a 28-year-old woman and her 3-year-old son with characteristics of white patches and forelock associated with numerous brown macules and patches. Genomic DNA samples of the proband and her son were extracted from their peripheral blood. One hundred unrelated healthy individuals were used as controls. All coding regions of KIT, SLUG, and NF1 genes were amplified by polymerase chain reaction using exon flanking intronic primers and Sanger sequencings were performed. DNA sequencing revealed heterozygous missense c.2431T>G mutation in exon 17 of the KIT gene in the proband and the affected son. No potentially pathogenic variant was identified in SLUG or NF1 genes. The nucleotide substitution was not found in 100 unrelated control individuals. This study reveals a novel KIT mutation in piebaldism, and it further supports that café-au-lait macules and intertriginous freckling of piebaldism are parts of pigmented anomaly in piebaldism, which does not necessarily represent coexistence of neurofibromatosis type 1 (NF1). PMID:25960657

  14. Novel splicing, missense, and deletion mutations in seven adenosine deaminase-deficient patients with late/delayed onset of combined immunodeficiency disease. Contribution of genotype to phenotype.

    PubMed Central

    Santisteban, I; Arredondo-Vega, F X; Kelly, S; Mary, A; Fischer, A; Hummell, D S; Lawton, A; Sorensen, R U; Stiehm, E R; Uribe, L

    1993-01-01

    We examined the genetic basis for adenosine deaminase (ADA) deficiency in seven patients with late/delayed onset of immunodeficiency, an underdiagnosed and relatively unstudied condition. Deoxyadenosine-mediated metabolic abnormalities were less severe than in the usual, early-onset disorder. Six patients were compound heterozygotes; 7 of 10 mutations found were novel, including one deletion (delta 1019-1020), three missense (Arg156 > His, Arg101 > Leu, Val177 > Met), and three splicing defects (IVS 5, 5'ss T+6 > A; IVS 10, 5'ss G+1 > A; IVS 10, 3'ss G-34 > A). Four of the mutations generated stop signals at codons 131, 321, 334, and 348; transcripts of all but the last, due to delta 1019-1020, were severely reduced. delta 1019-1020 (like delta 955-959, found in one patient and apparently recurrent) is at a short deletional hot spot. Arg156 > His, the product of which had detectable activity, was found in three patients whose second alleles were unlikely to yield active ADA. The oldest patient diagnosed was homozygous for a single base change in intron 10, which activates a cryptic splice acceptor, resulting in a protein with 100 extra amino acids. We speculate that this "macro ADA," as well as the Arg156 > His, Arg101 > Leu, Ser291 > Leu, and delta 1019-1020 products, may contribute to mild phenotype. Tissue-specific variation in splicing efficiency may also ameliorate disease severity in patients with splicing mutations. Images PMID:8227344

  15. HDR syndrome: a follow-up genotype-phenotype analysis of a de novo missense Thr272Ile mutation in exon 4 of GATA3.

    PubMed

    Gomes, T S; Gortner, L; Dockter, G; Leitner, D; Thakker, R V; Rohrer, T

    2012-11-01

    Hypoparathyroidism, sensorineural deafness and renal dysplasia (HDR) syndrome (MIM 146255) is a rare autosomal dominant disorder caused by mutations in the gene encoding GATA3, a dual zinc-finger transcription factor involved in vertebrate embryonic development. In this clinical case study we report on a follow-up of a phenotype associated with a GATA3 mutation. HDR syndrome was clinically diagnosed at age of 1.5 years in a boy with a de novo heterozygous missense (c.815C→T) mutation, Thr272Ile, in exon 4 of the GATA3 gene. Both parents were negative for Thr272Ile.At age of 17 months, the patient had a weight of 10.7, a body length of 78 cm, and a head circumference of 47.5 cm. By the age of 7 years, growth is age-appropriate, severe bilateral hearing loss (dB 60) was corrected by hearing aids. However, cognitive development (auditory sensory me-mory and language abilities) is at the lower ends of the test scores.In conclusion, a mildly impaired clinical course was achieved by the age of 7 years in a patient with HDR syndrome; this report adds to the body of data on genotype-phenotype analysis in HDR syndrome. · PMID:23203342

  16. The albinism of the feral Asinara white donkeys (Equus asinus) is determined by a missense mutation in a highly conserved position of the tyrosinase (TYR) gene deduced protein.

    PubMed

    Utzeri, V J; Bertolini, F; Ribani, A; Schiavo, G; Dall'Olio, S; Fontanesi, L

    2016-02-01

    A feral donkey population (Equus asinus), living in the Asinara National Park (an island north-west of Sardinia, Italy), includes a unique white albino donkey subpopulation or colour morph that is a major attraction of this park. Disrupting mutations in the tyrosinase (TYR) gene are known to cause recessive albinisms in humans (oculocutaneous albinism Type 1; OCA1) and other species. In this study, we analysed the donkey TYR gene as a strong candidate to identify the causative mutation of the albinism of these donkeys. The TYR gene was sequenced from 13 donkeys (seven Asinara white albino and six coloured animals). Seven single nucleotide polymorphisms were identified. A missense mutation (c.604C>G; p.His202Asp) in a highly conserved amino acid position (even across kingdoms), which disrupts the first copper-binding site (CuA) of functional protein, was identified in the homozygous condition (G/G or D/D) in all Asinara white albino donkeys and in the albino son of a trio (the grey parents had genotype C/G or H/D), supporting the recessive mode of inheritance of this mutation. Genotyping 82 donkeys confirmed that Asinara albino donkeys had genotype G/G whereas all other coloured donkeys had genotype C/C or C/G. Across-population association between the c.604C>G genotypes and the albino coat colour was highly significant (P = 6.17E-18). The identification of the causative mutation of the albinism in the Asinara white donkeys might open new perspectives to study the dynamics of this putative deleterious allele in a feral population and to manage this interesting animal genetic resource. PMID:26763160

  17. A novel missense mutation in the NSDHL gene identified in a Lithuanian family by targeted next-generation sequencing causes CK syndrome.

    PubMed

    Preiksaitiene, Egle; Caro, Alfonso; Benušienė, Eglė; Oltra, Silvestre; Orellana, Carmen; Morkūnienė, Aušra; Roselló, Mónica Pilar; Kasnauskiene, Jurate; Monfort, Sandra; Kučinskas, Vaidutis; Mayo, Sonia; Martinez, Francisco

    2015-06-01

    The NSDHL gene encodes 3β-hydroxysteroid dehydrogenase involved in one of the later steps of the cholesterol biosynthetic pathway. Mutations in this gene can cause CHILD syndrome (OMIM 308050) and CK syndrome (OMIM 300831). CHILD syndrome is an X-linked dominant, male lethal disorder caused by mutations in the NSDHL gene that result in the loss of the function of the NSDHL protein. CK syndrome is an allelic X-linked recessive disorder. So far, 13 patients with CK syndrome from two families have been reported on. We present a new five-generation family with affected males manifesting clinical features of CK syndrome. Next generation sequencing was targeted to a custom panel of 542 genes with known or putative implication on intellectual disability. Missense mutation p.Gly152Asp was identified in the NSDHL gene in the DNA sample of the affected male. Mutation carrier status was confirmed for all the obligate carriers in the family. The clinical features of the affected males in the family manifested as weak fetal movements, severe intellectual disability, seizures, spasticity, atrophy of optic discs, microcephaly, plagiocephaly, skeletal abnormalities, and minor facial anomalies, including a high nasal bridge, strabismus, and micrognathia. A highly significant preferential transmission of the mutation was observed in this and previous families segregating CK syndrome. Our report expands the clinical spectrum of this syndrome to include weak fetal movements, spasticity, and plagiocephaly, and transmission ratio distortion. The various findings in these patients increase our understanding of the diversity of the clinical presentation of cholesterol biosynthesis disorders. PMID:25900314

  18. A Missense Mutation in the Human Cytochrome b5 Gene causes 46,XY Disorder of Sex Development due to True Isolated 17,20 Lyase Deficiency

    PubMed Central

    Idkowiak, Jan; Randell, Tabitha; Dhir, Vivek; Patel, Pushpa; Shackleton, Cedric H. L.; Taylor, Norman F.; Krone, Nils

    2012-01-01

    Context: Isolated 17,20 lyase deficiency is commonly defined by apparently normal 17α-hydroxylase activity but severely reduced 17,20 lyase activity of the bifunctional enzyme cytochrome P450 (CYP) enzyme 17A1 (CYP17A1), resulting in sex steroid deficiency but normal glucocorticoid and mineralocorticoid reserve. Cytochrome b5 (CYB5A) is thought to selectively enhance 17,20 lyase activity by facilitating the allosteric interaction of CYP17A1 with its electron donor P450 oxidoreductase (POR). Objective: We investigated a large consanguineous family including three siblings with 46,XY disorder of sex development (DSD) presenting with isolated 17,20 lyase deficiency. Design: We investigated the clinical and biochemical phenotype, conducted genetic analyses, and functionally characterized the identified CYB5A mutation in cell-based CYP17A1 coexpression assays. Results: All three siblings presented with 46,XY DSD, sex steroid deficiency, normal mineralocorticoids and glucocorticoids, and a urine steroid metabolome suggestive of isolated 17,20 lyase deficiency. CYP17A1 and POR sequences were normal, but we detected a homozygous CYB5A missense mutation (g.28,400A→T; p.H44L). Functional in vitro analysis revealed normal CYP17A1 17α-hydroxylase activity but severely impaired 17,20 lyase activity. In silico analysis suggested the disruption of CYB5A heme binding by p.H44L. Conclusion: We have identified the first human CYB5A missense mutation as the cause of isolated 17,20 lyase deficiency in three individuals with 46,XY DSD. Detailed review of previously reported cases with apparently isolated 17,20 lyase deficiency due to mutant CYP17A1 and POR reveals impaired 17α-hydroxylase activity as assessed by steroid metabolome analysis and short cosyntropin testing. This suggests that truly isolated 17,20 lyase deficiency is observed only in individuals with inactivating CYB5A mutations. PMID:22170710

  19. A missense mutation (G1506E) in the adhesion G domain of laminin-5 causes mild junctional epidermolysis bullosa.

    PubMed

    Scaturro, Maria; Posteraro, Patrizia; Mastrogiacomo, Alessandro; Zaccaria, Maria Letizia; De Luca, Naomi; Mazzanti, Cinzia; Zambruno, Giovanna; Castiglia, Daniele

    2003-09-12

    Laminin-5 is the major adhesion ligand for epithelial cells. Mutations in the genes encoding laminin-5 cause junctional epidermolysis bullosa (JEB), a recessive inherited disease characterized by extensive epithelial-mesenchymal disadhesion. We describe a JEB patient compound heterozygote for two novel mutations in the gene (LAMA3) encoding the laminin alpha3 chain. The maternal mutation (1644delG) generates mRNA transcripts that undergo nonsense-mediated decay. The paternal mutation results in the Gly1506-->Glu substitution (G1506E) within the C-terminal globular region of the alpha3 chain (G domain). Mutation G1506E affects the proper folding of the fourth module of the G domain and results in the retention of most of the mutated polypeptide within the endoplasmic reticulum (ER). However, scant amounts of the mutated laminin-5 are secreted, undergo physiologic extracellular maturation, and correctly localize within the cutaneous basement membrane zone in patient's skin. Our findings represent the first demonstration of an ER-retained mutant laminin-5 leading to a mild JEB phenotype. PMID:12943669

  20. Convergent Evolution of Head Crests in Two Domesticated Columbids Is Associated with Different Missense Mutations in EphB2.

    PubMed

    Vickrey, Anna I; Domyan, Eric T; Horvath, Martin P; Shapiro, Michael D

    2015-10-01

    Head crests are important display structures in wild bird species and are also common in domesticated lineages. Many breeds of domestic rock pigeon (Columba livia) have crests of reversed occipital feathers, and this recessive trait is associated with a nonsynonymous coding mutation in the intracellular kinase domain of EphB2 (Ephrin receptor B2). The domestic ringneck dove (Streptopelia risoria) also has a recessive crested morph with reversed occipital feathers, and interspecific crosses between crested doves and pigeons produce crested offspring, suggesting a similar genetic basis for this trait in both species. We therefore investigated EphB2 as a candidate for the head crest phenotype of ringneck doves and identified a nonsynonymous coding mutation in the intracellular kinase domain that is significantly associated with the crested morph. This mutation is over 100 amino acid positions away from the crest mutation found in rock pigeons, yet both mutations are predicted to negatively affect the function of ATP-binding pocket. Furthermore, bacterial toxicity assays suggest that "crest" mutations in both species severely impact kinase activity. We conclude that head crests are associated with different mutations in the same functional domain of the same gene in two different columbid species, thereby representing striking evolutionary convergence in morphology and molecules. PMID:26104009

  1. Pyruvate Kinase Deficiency in Sub-Saharan Africa: Identification of a Highly Frequent Missense Mutation (G829A;Glu277Lys) and Association with Malaria

    PubMed Central

    Machado, Patrícia; Manco, Licínio; Gomes, Cláudia; Mendes, Cristina; Fernandes, Natércia; Salomé, Graça; Sitoe, Luis; Chibute, Sérgio; Langa, José; Ribeiro, Letícia; Miranda, Juliana; Cano, Jorge; Pinto, João; Amorim, António; do Rosário, Virgílio E.; Arez, Ana Paula

    2012-01-01

    Background Pyruvate kinase (PK) deficiency, causing hemolytic anemia, has been associated to malaria protection and its prevalence in sub-Saharan Africa is not known so far. This work shows the results of a study undertaken to determine PK deficiency occurrence in some sub-Saharan African countries, as well as finding a prevalent PK variant underlying this deficiency. Materials and Methods Blood samples of individuals from four malaria endemic countries (Mozambique, Angola, Equatorial Guinea and Sao Tome and Principe) were analyzed in order to determine PK deficiency occurrence and detect any possible high frequent PK variant mutation. The association between this mutation and malaria was ascertained through association studies involving sample groups from individuals showing different malaria infection and outcome status. Results The percentage of individuals showing a reduced PK activity in Maputo was 4.1% and the missense mutation G829A (Glu277Lys) in the PKLR gene (only identified in three individuals worldwide to date) was identified in a high frequency. Heterozygous carrier frequency was between 6.7% and 2.6%. A significant association was not detected between either PK reduced activity or allele 829A frequency and malaria infection and outcome, although the variant was more frequent among individuals with uncomplicated malaria. Conclusions This was the first study on the occurrence of PK deficiency in several areas of Africa. A common PKLR mutation G829A (Glu277Lys) was identified. A global geographical co-distribution between malaria and high frequency of PK deficiency seems to occur suggesting that malaria may be a selective force raising the frequency of this 277Lys variant. PMID:23082140

  2. Identification of an A-to-G missense mutation in exon 2 of the UGT1 gene complex that causes Crigler-Najjar syndrome type 2

    SciTech Connect

    Moghrabi, N.; Clarke, D.J.; Boxer, M.; Burchell, B. )

    1993-10-01

    Crigler-Najjar syndrome is an inborn error of metabolism that is characterized by severe unconjugated hyperbilirubinemia. The disease is caused by a deficiency in the hepatic enzyme bilirubin UDP-glucoronosyl-transferase (UGT), which is responsible for the safe elimination of the toxic heme breakdown product bilirubin from the body via bile. Two types of the disease have been classified according to their clinical severity. Crigler-Najjar syndrome type 2 (CN-2) is a less severe form of the disease that is caused by a reduced ability to glucoronidate bilirubin, with serium bilirubin levels ranging from 60 to 340 [mu]M. The recent identification of a large gene locus termed UGT1 that encodes two bilirubin UGTs (UGT1*1 and UGT1*4) and two phenol UGTs (UGT1*02 and UGT1*6) has provided the tools for studying hereditary unconjugated hyperbilirubinemias. Recent analysis of five unrelated CN-1 patients has revealed the presence of several mutations in the UGT1 gene complex. Here, the authors present the first report of a mutation identified in a CN-2 patient and discuss the correlation of this mutation with the severity of the disease. The missense mutation identified in exon 2 of the CN-2 patient's DNA that is shared by several UGT1 genes is predicted to change a glutamine codon (CAG) to an arginine codon (CGG) at residue 331 of the bilirubin UGT isoenzymes, UGT1*1 and UGT1*4, and residue 329 of UGT1*02 and residue 327 of UGT1*6 of the phenol UGT isoenzymes. This agreed with enzymological and immunochemical studies, which demonstrated that the expression of all UGT1 proteins was affected in the CN-2 patient. 12 refs., 1 fig.

  3. A Saccharomyces Cerevisiae Rad52 Allele Expressing a C-Terminal Truncation Protein: Activities and Intragenic Complementation of Missense Mutations

    PubMed Central

    Boundy-Mills, K. L.; Livingston, D. M.

    1993-01-01

    A nonsense allele of the yeast RAD52 gene, rad52-327, which expresses the N-terminal 65% of the protein was compared to two missense alleles, rad52-1 and rad52-2, and to a deletion allele. While the rad52-1 and the deletion mutants have severe defects in DNA repair, recombination and sporulation, the rad52-327 and rad52-2 mutants retain either partial or complete capabilities in repair and recombination. These two mutants behave similarly in most tests of repair and recombination during mitotic growth. One difference between these two alleles is that a homozygous rad52-2 diploid fails to sporulate, whereas the homozygous rad52-327 diploid sporulates weakly. The low level of sporulation by the rad52-327 diploid is accompanied by a low percentage of spore viability. Among these viable spores the frequency of crossing over for markers along chromosome VII is the same as that found in wild-type spores. rad52-327 complements rad52-2 for repair and sporulation. Weaker intragenic complementation occurs between rad52-327 and rad52-1. PMID:8417987

  4. A Missense Mutation in the Zinc Finger Domain of OsCESA7 Deleteriously Affects Cellulose Biosynthesis and Plant Growth in Rice

    PubMed Central

    Wang, Daofeng; Qin, Yanling; Fang, Jingjing; Yuan, Shoujiang; Peng, Lixiang; Zhao, Jinfeng; Li, Xueyong

    2016-01-01

    Rice is a model plant species for the study of cellulose biosynthesis. We isolated a mutant, S1-24, from ethyl methanesulfonate (EMS)-treated plants of the japonica rice cultivar, Nipponbare. The mutant exhibited brittle culms and other pleiotropic phenotypes such as dwarfism and partial sterility. The brittle culms resulted from reduced mechanical strength due to a defect in thickening of the sclerenchyma cell wall and reduced cellulose content in the culms of the S1-24 mutant. Map-based gene cloning and a complementation assay showed that phenotypes of the S1-24 mutant were caused by a recessive point mutation in the OsCESA7 gene, which encodes cellulose synthase A subunit 7. The missense mutation changed the highly conserved C40 to Y in the zinc finger domain. The OsCESA7 gene is expressed predominantly in the culm at the mature stage, particularly in mechanical tissues such as vascular bundles and sclerenchyma cells, consistent with the brittle phenotype in the culm. These results indicate that OsCESA7 plays an important role in cellulose biosynthesis and plant growth. PMID:27092937

  5. Niemann-Pick disease: A frequent missense mutation in the acid sphingomyelinase gene of Ashkenazi Jewish type A and B patients

    SciTech Connect

    Levran, O.; Desnick, R.J.; Schuchan, E.H. )

    1991-05-01

    Although the A and B subtypes of Niemann-Pick disease (NPD) both result from the deficient activity of acid sphingomyelinase and the lysosomal accumulation of sphingomyelin, they have remarkably distinct phenotypes. Type A disease is a fatal neurodegenerative disorder of infancy, whereas type B disease has no neurologic manifestations and is characterized primarily by reticuloendothelial involvement and survival into adulthood. Both disorders are more frequent among individuals of Ashkenazi Jewish ancestry than in the general population. The recent isolation and characterization of cDNA and genomic sequences encoding ASM has facilitated investigation of the molecular lesions causing the NPD subtypes. Total RNA was reverse-transcribed, and the ASm cDNA from an Ashkenazi Jewish type A patient was specifically amplified by the polymerase chain reaction (PCR). Molecular analysis of the PCR products revealed a G{r arrow} T transversion of nucleotide 1,487, which occurred at a CpG dinucleotide and predicted an Arg{r arrow} Leu substitution and that both parents and several other relatives were heterozygous. These findings identify a frequent missense mutation among NPD patients of Ashkenazi Jewish ancestry that results in neuronopathic type A disease when homoallelic and can result in the nonneuronopathic type B phenotype when heteroallelic. The identification of this ASM mutation in Ashkenazi Jewish patients should facilitate the prevention of NPD in this population by carrier detection with molecular diagnostic techniques.

  6. A Missense Mutation in the Zinc Finger Domain of OsCESA7 Deleteriously Affects Cellulose Biosynthesis and Plant Growth in Rice.

    PubMed

    Wang, Daofeng; Qin, Yanling; Fang, Jingjing; Yuan, Shoujiang; Peng, Lixiang; Zhao, Jinfeng; Li, Xueyong

    2016-01-01

    Rice is a model plant species for the study of cellulose biosynthesis. We isolated a mutant, S1-24, from ethyl methanesulfonate (EMS)-treated plants of the japonica rice cultivar, Nipponbare. The mutant exhibited brittle culms and other pleiotropic phenotypes such as dwarfism and partial sterility. The brittle culms resulted from reduced mechanical strength due to a defect in thickening of the sclerenchyma cell wall and reduced cellulose content in the culms of the S1-24 mutant. Map-based gene cloning and a complementation assay showed that phenotypes of the S1-24 mutant were caused by a recessive point mutation in the OsCESA7 gene, which encodes cellulose synthase A subunit 7. The missense mutation changed the highly conserved C40 to Y in the zinc finger domain. The OsCESA7 gene is expressed predominantly in the culm at the mature stage, particularly in mechanical tissues such as vascular bundles and sclerenchyma cells, consistent with the brittle phenotype in the culm. These results indicate that OsCESA7 plays an important role in cellulose biosynthesis and plant growth. PMID:27092937

  7. X-linked cone dystrophy and colour vision deficiency arising from a missense mutation in a hybrid L/M cone opsin gene

    PubMed Central

    McClements, Michelle; Davies, Wayne I L; Michaelides, Michel; Carroll, Joseph; Rha, Jungate; Mollon, John D; Neitz, Maureen; MacLaren, Robert E; Moore, Anthony T; Hunt, David M

    2013-01-01

    In this report, we describe a male subject who presents with a complex phenotype of myopia associated with cone dysfunction and a protan vision deficiency. Retinal imaging demonstrates extensive cone disruption, including the presence of non-waveguiding cones, an overall thinning of the retina, and an irregular mottled appearance of the hyper reflective band associated with the inner segment ellipsoid portion of the photoreceptor. Mutation screening revealed a novel p.Glu41Lys missense mutation in a hybrid L/M opsin gene. Spectral analysis shows that the mutant opsin fails to form a pigment in vitro and fails to be trafficked to the cell membrane in transfected Neuro2a cells. Extensive sequence and quantitative PCR analysis identifies this mutant gene as the only gene present in the affected subject’s L/M opsin gene array, yet the presence of protanopia indicates that the mutant opsin must retain some activity in vivo. To account for this apparent contradiction, we propose that a limited amount of functional pigment is formed within the normal cellular environment of the intact photoreceptor, and that this requires the presence of chaperone proteins that promote stability and normal folding of the mutant protein. PMID:23337435

  8. Two Novel Missense Mutations and a 5bp Deletion in the Erythroid-Specific Promoter of the PKLR Gene in Two Unrelated Patients With Pyruvate Kinase Deficient Transfusion-Dependent Chronic Nonspherocytic Hemolytic Anemia.

    PubMed

    Kager, Leo; Minkov, Milen; Zeitlhofer, Petra; Fahrner, Bernhard; Ratzinger, Franz; Boztug, Kaan; Dossenbach-Glaninger, Astrid; Haas, Oskar A

    2016-05-01

    We report two children with severe chronic hemolytic anemia, the cause of which was difficult to establish because of transfusion dependency. Reduced erythrocyte pyruvate kinase activity in their asymptomatic parents provided the diagnostic clues for mutation screening of the PKLR gene and revealed that one child was a compound heterozygote of a novel paternally derived 5-bp deletion in the promoter region (c.-88_-84delTCTCT) and a maternally derived missense mutation in exon nine (c.1174G>A; p.Ala392Thr). The second child was a compound heterozygote of two novel missense mutations, namely a paternally derived exon ten c.1381G>A (p.Glu461Lys) and a maternally derived exon seven c.907-908delCC (p.Pro303GlyfsX12) variant. PMID:26728349

  9. Caveolin-3 T78M and T78K missense mutations lead to different phenotypes in vivo and in vitro.

    PubMed

    Traverso, Monica; Gazzerro, Elisabetta; Assereto, Stefania; Sotgia, Federica; Biancheri, Roberta; Stringara, Silvia; Giberti, Laura; Pedemonte, Marina; Wang, Xiabo; Scapolan, Sara; Pasquini, Elisabetta; Donati, Maria A; Zara, Federico; Lisanti, Michael P; Bruno, Claudio; Minetti, Carlo

    2008-03-01

    Caveolins are the principal protein components of caveolae, invaginations of the plasma membrane involved in cell signaling and trafficking. Caveolin-3 (Cav-3) is the muscle-specific isoform of the caveolin family and mutations in the CAV3 gene lead to a large group of neuromuscular disorders. In unrelated patients, we identified two distinct CAV3 mutations involving the same codon 78. Patient 1, affected by dilated cardiomyopathy and limb girdle muscular dystrophy (LGMD)-1C, shows an autosomal recessive mutation converting threonine to methionine (T78M). Patient 2, affected by isolated familiar hyperCKemia, shows an autosomal dominant mutation converting threonine to lysine (T78K). Cav-3 wild type (WT) and Cav-3 mutations were transiently transfected into Cos-7 cells. Cav-3 WT and Cav-3 T78M mutant localized at the plasma membrane, whereas Cav-3 T78K was retained in a perinuclear compartment. Cav-3 T78K expression was decreased by 87% when compared with Cav-3 WT, whereas Cav-3 T78M protein levels were unchanged. To evaluate whether Cav-3 T78K and Cav-3 T78M mutants behaved with a dominant negative pattern, Cos-7 cells were cotransfected with green fluorescent protein (GFP)-Cav-3 WT in combination with either mutant or WT Cav-3. When cotransfected with Cav-3 WT or Cav-3 T78M, GFP-Cav-3 WT was localized at the plasma membrane, as expected. However, when cotransfected with Cav-3 T78K, GFP-Cav-3 WT was retained in a perinuclear compartment, and its protein levels were reduced by 60%, suggesting a dominant negative action. Accordingly, Cav-3 protein levels in muscles from a biopsy of patient 2 (T78K mutation) were reduced by 80%. In conclusion, CAV3 T78M and T78K mutations lead to distinct disorders showing different clinical features and inheritance, and displaying distinct phenotypes in vitro. PMID:18253147

  10. Novel m.15434C>A (p.230L>I) Mitochondrial Cytb Gene Missense Mutation Associated with Dilated Cardiomyopathy

    PubMed Central

    Zarrouk Mahjoub, Sinda; Mehri, Sounira; Ourda, Fatma; Finsterer, Josef; Ben Arab, Saïda

    2012-01-01

    Background. Previously it has been shown that various types of hypertrophic and dilative cardiomyopathy (hCMP, dCMP) can be attributed to disturbed mitochondrial oxidative energy metabolism. Several studies described mutations in mitochondrial DNA-located genes encoding for subunits of respiratory chain complexes, including the cytochrome b gene (MT-CYB), causing CMPs. Methods and Results. In the present study the MT-CYB gene was analysed in 30 patients with hCMP, 40 patients with dCMP, and 50 controls for alterations. Altogether, 27 MT-CYB variants were detected. Twenty-four of them were single nucleotide polymorphisms defining common haplogroups. The variant m.15434C>A was found in a single patient with severe dCMP and assessed as novel mutation, since it was not found in healthy controls or available data sets, and was nonhaplogroup associated with Phylotree. This variant altered an amino acid (L230I) with a high interspecific amino acid conservation index (CI = 97.7%) indicative of the functional importance of the residue. Conclusions. Though the L230I mutation seems to play a causative role for dCMP, prospective studies on yeast or transgenic mice models with defined mutation are warranted to study the pathogenetic impact of this mutation. PMID:22811935

  11. A missense mutation in PPP1R15B causes a syndrome including diabetes, short stature and microcephaly

    PubMed Central

    Igoillo-Esteve, Mariana; Daures, Mathilde; Romero, Sophie; Philippi, Anne; Senée, Valérie; Lopes, Miguel; Cunha, Daniel A.; Harding, Heather P.; Derbois, Céline; Bendelac, Nathalie; Hattersley, Andrew T.; Eizirik, Décio L.; Ron, David

    2015-01-01

    Dysregulated endoplasmic reticulum stress and phosphorylation of eukaryotic translation initiation factor 2α (eIF2α) are associated with pancreatic β-cell failure and diabetes. Here we report the first homozygous mutation in the PPP1R15B gene (also known as constitutive repressor of eIF2α phosphorylation, CReP), encoding the regulatory subunit of an eIF2α-specific phosphatase, in two siblings affected by a novel syndrome of diabetes of youth, with short stature, intellectual disability and microcephaly. The R658C mutation in PPP1R15B affects a conserved amino acid within the domain important for protein phosphatase 1 (PP1) binding. The R658C mutation decreases PP1 binding and eIF2α dephosphorylation, and results in β-cell apoptosis. Our findings support the concept that dysregulated eIF2α phosphorylation, whether decreased by mutation of the kinase (EIF2AK3) in Wolcott-Rallison syndrome or increased by mutation of the phosphatase (PPP1R15B), is deleterious to β-cells and other secretory tissues, resulting in diabetes associated with multi-system abnormalities. PMID:26159176

  12. A missense mutation in the cystathionine {beta}-synthase (CBS) gene associated with pyridoxine (B{sub 6}) responsive homocystinuria

    SciTech Connect

    Shih, V.E.; Fringer, J.M.; Mandell, R.

    1994-09-01

    CBS deficiency is an autosomal recessive disorder characterized by homocystinuria and multisystem clinical disease. B{sub 6} responsive patients usually have a milder clinical phenotype than B{sub 6} nonresponsive patients. In our ongoing studies of the molecular defects in CBS deficiency, we reported a T-833 to C transition causing a substitution of threonine for isoleucine at position 278 (I278T). By PCR amplification and sequencing of exon 8 from genomic DNA we have now identified 2 index patients who are homozygous and 5 who are heterozygous for this mutation in a group of 32 patients with CBS deficiency. The mutation was detected in 7 of 10 unrelated families with in vivo B{sub 6} responsiveness, including one with a partial response, and in 0 of 22 B{sub 6} nonresponsive patients. The mutations on the other allele in the compound heterozygotes are still under investigation. We have now observed the I278T mutation in 9 of 20 independent alleles of varied ethnic backgrounds in the subgroup of B{sub 6} responsive patients. These findings, together with the previous report of this mutation in one allele of a B{sub 6} responsive patient, suggest that the I278T mutation is associated with B{sub 6} responsiveness in CBS deficiency. In compound heterozygotes, the degree of B{sub 6} responsiveness may also depend upon the nature of the other mutant allele and/or the interaction between the polypeptide subunits produced by the two mutant allelic genes.

  13. A novel hypothyroid dwarfism due to the missense mutation Arg479Cys of the thyroid peroxidase gene in the mouse.

    PubMed

    Takabayashi, Shuji; Umeki, Kazumi; Yamamoto, Etsuko; Suzuki, Tohru; Okayama, Akihiko; Katoh, Hideki

    2006-10-01

    Recently, we found a novel dwarf mutation in an ICR closed colony. This mutation was governed by a single autosomal recessive gene. In novel dwarf mice, plasma levels of the thyroid hormones, T3 and T4, were reduced; however, TSH was elevated. Their thyroid glands showed a diffuse goiter exhibiting colloid deficiency and abnormal follicle epithelium. The dwarfism was improved by adding thyroid hormone in the diet. Gene mapping revealed that the dwarf mutation was closely linked to the thyroid peroxidase (Tpo) gene on chromosome 12. Sequencing of the Tpo gene of the dwarf mice demonstrated a C to T substitution at position 1508 causing an amino acid change from arginine (Arg) to cysteine (Cys) at codon 479 (Arg479Cys). Western blotting revealed that TPO protein of the dwarf mice was detected in a microsomal fraction of thyroid tissue, but peroxidase activity was not detected. These findings suggested that the dwarf mutation caused a primary congenital hypothyroidism by TPO deficiency, resulting in a defect of thyroid hormone synthesis. PMID:16762971

  14. Subnuclear re-localization of SOX10 and p54NRB correlates with a unique neurological phenotype associated with SOX10 missense mutations.

    PubMed

    Chaoui, Asma; Kavo, Anthula; Baral, Viviane; Watanabe, Yuli; Lecerf, Laure; Colley, Alison; Mendoza-Londono, Roberto; Pingault, Veronique; Bondurand, Nadege

    2015-09-01

    SOX10 is a transcription factor with well-known functions in neural crest and oligodendrocyte development. Mutations in SOX10 were first associated with Waardenburg-Hirschsprung disease (WS4; deafness, pigmentation defects and intestinal aganglionosis). However, variable phenotypes that extend beyond the WS4 definition are now reported. The neurological phenotypes associated with some truncating mutations are suggested to be the result of escape from the nonsense-mediated mRNA decay pathway; but, to date, no mechanism has been suggested for missense mutations, of which approximately 20 have now been reported, with about half of the latter shown to be redistributed to nuclear bodies of undetermined nature and function in vitro. Here, we report that p54NRB, which plays a crucial role in the regulation of gene expression during many cellular processes including differentiation, interacts synergistically with SOX10 to regulate several target genes. Interestingly, this paraspeckle protein, as well as two other members of the Drosophila behavior human splicing (DBHS) protein family, co-localize with SOX10 mutants in nuclear bodies, suggesting the possible paraspeckle nature of these foci or re-localization of the DBHS members to other subnuclear compartments. Remarkably, the co-transfection of wild-type and mutant SOX10 constructs led to the sequestration of wild-type protein in mutant-induced foci. In contrast to mutants presenting with additional cytoplasmic re-localization, those exclusively found in the nucleus alter synergistic activity between SOX10 and p54NRB. We propose that such a dominant negative effect may contribute to or be at the origin of the unique progressive and severe neurological phenotype observed in affected patients. PMID:26060192

  15. Missense mutation in DISC1 C-terminal coiled-coil has GSK3β signaling and sex-dependent behavioral effects in mice

    PubMed Central

    Dachtler, James; Elliott, Christina; Rodgers, R. John; Baillie, George S.; Clapcote, Steven J.

    2016-01-01

    Disrupted-in-Schizophrenia 1 (DISC1) is a risk factor for schizophrenia and affective disorders. The full-length DISC1 protein consists of an N-terminal ‘head’ domain and a C-terminal tail domain that contains several predicted coiled-coils, structural motifs involved in protein-protein interactions. To probe the in vivo effects of missense mutation of DISC1’s C-terminal tail, we tested mice carrying mutation D453G within a predicted α-helical coiled-coil region. We report that, relative to wild-type littermates, female DISC1D453G mice exhibited novelty-induced hyperlocomotion, an anxiogenic profile in the elevated plus-maze and open field tests, and reduced social exploration of unfamiliar mice. Male DISC1D453G mice displayed a deficit in passive avoidance, while neither males nor females exhibited any impairment in startle reactivity or prepulse inhibition. Whole brain homogenates showed normal levels of DISC1 protein, but decreased binding of DISC1 to GSK3β, decreased phospho-inhibition of GSK3β at serine 9, and decreased levels of β-catenin in DISC1D453G mice of either sex. Interrupted GSK3β signaling may thus be part of the mechanism underlying the behavioral phenotype associated with D453G, in common with the previously described N-terminal domain mutations Q31L and L100P in mice, and the schizophrenia risk-conferring variant R264Q in humans. PMID:26728762

  16. Missense mutation in DISC1 C-terminal coiled-coil has GSK3β signaling and sex-dependent behavioral effects in mice.

    PubMed

    Dachtler, James; Elliott, Christina; Rodgers, R John; Baillie, George S; Clapcote, Steven J

    2016-01-01

    Disrupted-in-Schizophrenia 1 (DISC1) is a risk factor for schizophrenia and affective disorders. The full-length DISC1 protein consists of an N-terminal 'head' domain and a C-terminal tail domain that contains several predicted coiled-coils, structural motifs involved in protein-protein interactions. To probe the in vivo effects of missense mutation of DISC1's C-terminal tail, we tested mice carrying mutation D453G within a predicted α-helical coiled-coil region. We report that, relative to wild-type littermates, female DISC1(D453G) mice exhibited novelty-induced hyperlocomotion, an anxiogenic profile in the elevated plus-maze and open field tests, and reduced social exploration of unfamiliar mice. Male DISC1(D453G) mice displayed a deficit in passive avoidance, while neither males nor females exhibited any impairment in startle reactivity or prepulse inhibition. Whole brain homogenates showed normal levels of DISC1 protein, but decreased binding of DISC1 to GSK3β, decreased phospho-inhibition of GSK3β at serine 9, and decreased levels of β-catenin in DISC1(D453G) mice of either sex. Interrupted GSK3β signaling may thus be part of the mechanism underlying the behavioral phenotype associated with D453G, in common with the previously described N-terminal domain mutations Q31L and L100P in mice, and the schizophrenia risk-conferring variant R264Q in humans. PMID:26728762

  17. Missense Mutation R338W in ARHGEF9 in a Family with X-linked Intellectual Disability with Variable Macrocephaly and Macro-Orchidism

    PubMed Central

    Long, Philip; May, Melanie M.; James, Victoria M.; Grannò, Simone; Johnson, John P.; Tarpey, Patrick; Stevenson, Roger E.; Harvey, Kirsten; Schwartz, Charles E.; Harvey, Robert J.

    2016-01-01

    Non-syndromal X-linked intellectual disability (NS-XLID) represents a broad group of clinical disorders in which ID is the only clinically consistent manifestation. Although in many cases either chromosomal linkage data or knowledge of the >100 existing XLID genes has assisted mutation discovery, the underlying cause of disease remains unresolved in many families. We report the resolution of a large family (K8010) with NS-XLID, with variable macrocephaly and macro-orchidism. Although a previous linkage study had mapped the locus to Xq12-q21, this region contained too many candidate genes to be analyzed using conventional approaches. However, X-chromosome exome sequencing, bioinformatics analysis and segregation analysis revealed a novel missense mutation (c.1012C>T; p.R338W) in ARHGEF9. This gene encodes collybistin (CB), a neuronal GDP-GTP exchange factor previously implicated in several cases of XLID, as well as clustering of gephyrin and GABAA receptors at inhibitory synapses. Molecular modeling of the CB R338W substitution revealed that this change results in the substitution of a long electropositive side-chain with a large non-charged hydrophobic side-chain. The R338W change is predicted to result in clashes with adjacent amino acids (K363 and N335) and disruption of electrostatic potential and local folding of the PH domain, which is known to bind phosphatidylinositol-3-phosphate (PI3P/PtdIns-3-P). Consistent with this finding, functional assays revealed that recombinant CB CB2SH3−R338W was deficient in PI3P binding and was not able to translocate EGFP-gephyrin to submembrane microaggregates in an in vitro clustering assay. Taken together, these results suggest that the R338W mutation in ARHGEF9 is the underlying cause of NS-XLID in this family. PMID:26834553

  18. Dominant Red Coat Color in Holstein Cattle Is Associated with a Missense Mutation in the Coatomer Protein Complex, Subunit Alpha (COPA) Gene

    PubMed Central

    Dorshorst, Ben; Henegar, Corneliu; Liao, Xiaoping; Sällman Almén, Markus; Rubin, Carl-Johan; Ito, Shosuke; Wakamatsu, Kazumasa; Stothard, Paul; Van Doormaal, Brian; Plastow, Graham; Barsh, Gregory S.; Andersson, Leif

    2015-01-01

    Coat color in Holstein dairy cattle is primarily controlled by the melanocortin 1 receptor (MC1R) gene, a central determinant of black (eumelanin) vs. red/brown pheomelanin synthesis across animal species. The major MC1R alleles in Holsteins are Dominant Black (MC1RD) and Recessive Red (MC1Re). A novel form of dominant red coat color was first observed in an animal born in 1980. The mutation underlying this phenotype was named Dominant Red and is epistatic to the constitutively activated MC1RD. Here we show that a missense mutation in the coatomer protein complex, subunit alpha (COPA), a gene with previously no known role in pigmentation synthesis, is completely associated with Dominant Red in Holstein dairy cattle. The mutation results in an arginine to cysteine substitution at an amino acid residue completely conserved across eukaryotes. Despite this high level of conservation we show that both heterozygotes and homozygotes are healthy and viable. Analysis of hair pigment composition shows that the Dominant Red phenotype is similar to the MC1R Recessive Red phenotype, although less effective at reducing eumelanin synthesis. RNA-seq data similarly show that Dominant Red animals achieve predominantly pheomelanin synthesis by downregulating genes normally required for eumelanin synthesis. COPA is a component of the coat protein I seven subunit complex that is involved with retrograde and cis-Golgi intracellular coated vesicle transport of both protein and RNA cargo. This suggests that Dominant Red may be caused by aberrant MC1R protein or mRNA trafficking within the highly compartmentalized melanocyte, mimicking the effect of the Recessive Red loss of function MC1R allele. PMID:26042826

  19. Dominant Red Coat Color in Holstein Cattle Is Associated with a Missense Mutation in the Coatomer Protein Complex, Subunit Alpha (COPA) Gene.

    PubMed

    Dorshorst, Ben; Henegar, Corneliu; Liao, Xiaoping; Sällman Almén, Markus; Rubin, Carl-Johan; Ito, Shosuke; Wakamatsu, Kazumasa; Stothard, Paul; Van Doormaal, Brian; Plastow, Graham; Barsh, Gregory S; Andersson, Leif

    2015-01-01

    Coat color in Holstein dairy cattle is primarily controlled by the melanocortin 1 receptor (MC1R) gene, a central determinant of black (eumelanin) vs. red/brown pheomelanin synthesis across animal species. The major MC1R alleles in Holsteins are Dominant Black (MC1RD) and Recessive Red (MC1Re). A novel form of dominant red coat color was first observed in an animal born in 1980. The mutation underlying this phenotype was named Dominant Red and is epistatic to the constitutively activated MC1RD. Here we show that a missense mutation in the coatomer protein complex, subunit alpha (COPA), a gene with previously no known role in pigmentation synthesis, is completely associated with Dominant Red in Holstein dairy cattle. The mutation results in an arginine to cysteine substitution at an amino acid residue completely conserved across eukaryotes. Despite this high level of conservation we show that both heterozygotes and homozygotes are healthy and viable. Analysis of hair pigment composition shows that the Dominant Red phenotype is similar to the MC1R Recessive Red phenotype, although less effective at reducing eumelanin synthesis. RNA-seq data similarly show that Dominant Red animals achieve predominantly pheomelanin synthesis by downregulating genes normally required for eumelanin synthesis. COPA is a component of the coat protein I seven subunit complex that is involved with retrograde and cis-Golgi intracellular coated vesicle transport of both protein and RNA cargo. This suggests that Dominant Red may be caused by aberrant MC1R protein or mRNA trafficking within the highly compartmentalized melanocyte, mimicking the effect of the Recessive Red loss of function MC1R allele. PMID:26042826

  20. A missense mutation in the neutrophil cytochrome b heavy chain in cytochrome-positive X-linked chronic granulomatous disease.

    PubMed Central

    Dinauer, M C; Curnutte, J T; Rosen, H; Orkin, S H

    1989-01-01

    A membrane-bound cytochrome b, a heterodimer formed by a 91-kD glycoprotein and a 22-kD polypeptide, is a critical component of the phagocyte NADPH-oxidase responsible for the generation of superoxide anion. Mutations in the gene for the 91-kD chain of this cytochrome result in the X-linked form of chronic granulomatous disease (CGD), in which phagocytes are unable to produce superoxide. Typically, there is a marked deficiency of the 91-kD subunit and the cytochrome spectrum is absent (X- CGD). In a variant form of CGD with X-linked inheritance, affected males have a normal visible absorbance spectrum of cytochrome b, yet fail to generate superoxide (X+ CGD). The size and abundance of the mRNA for the 91-kD subunit and its encoded protein were examined and appeared normal. To search for a putative mutation in the coding sequence of the 91-kD subunit gene, the corresponding RNA from an affected X+ male was amplified by the polymerase chain reaction and sequenced. A single nucleotide change, a C----A transversion, was identified that predicts a nonconservative Pro----His substitution at residue 415 of the encoded protein. Hybridization of amplified genomic DNA with allele-specific oligonucleotide probes demonstrated the mutation to be specific to affected X+ males and the carrier state. These results strengthen the concept that all X-linked CGD relates to mutations affecting the expression or structure of the 91-kD cytochrome b subunit. The mechanism by which the Pro 415----His mutation renders the oxidase nonfunctional is unknown, but may involve an impaired interaction with other components of the oxidase. Images PMID:2556453

  1. Hereditary angioedema in a Jordanian family with a novel missense mutation in the C1-inhibitor N-terminal domain.

    PubMed

    Jaradat, Saied A; Caccia, Sonia; Rawashdeh, Rifaat; Melhem, Motasem; Al-Hawamdeh, Ali; Carzaniga, Thomas; Haddad, Hazem

    2016-03-01

    Hereditary angioedema due to C1-inhibitor deficiency (C1-INH-HAE) is an autosomal dominant disease caused by mutations in the SERPING1 gene. A Jordanian family, including 14 individuals with C1-INH-HAE clinical symptoms, was studied. In the propositus and his parents, SERPING1 had four mutations leading to amino acid substitutions. Two are known polymorphic variants (c.167T>C; p.Val34Ala and c.1438G>A; p.Val458Met), the others are newly described. One (c.203C>T; p.Thr46Ile) is located in the N-terminal domain of the C1-inhibitor protein and segregates with angioedema symptoms in the family. The other (c.800C>T; p.Ala245Val) belongs to the serpin domain, and derives from the unaffected father. DNA from additional 24 family members were screened for c.203C>T mutation in the target gene. All individuals heterozygous for the c.203C>T mutation had antigenic and functional plasma levels of C1-inhibitor below 50% of normal, confirming the diagnosis of type I C1-INH-HAE. Angioedema symptoms were present in 14 of 16 subjects carrier for the c.203T allele. Among these subjects, those carrying the c.800T variation had more severe and frequent symptoms than subjects without this mutation. This family-based study provides the first evidence that multiple amino acid substitutions in SERPING1 could influence C1-INH-HAE phenotype. PMID:26895475

  2. Impaired riboflavin transport due to missense mutations in SLC52A2 causes Brown-Vialetto-Van Laere syndrome.

    PubMed

    Haack, Tobias B; Makowski, Christine; Yao, Yoshiaki; Graf, Elisabeth; Hempel, Maja; Wieland, Thomas; Tauer, Ulrike; Ahting, Uwe; Mayr, Johannes A; Freisinger, Peter; Yoshimatsu, Hiroki; Inui, Ken; Strom, Tim M; Meitinger, Thomas; Yonezawa, Atsushi; Prokisch, Holger

    2012-11-01

    Brown-Vialetto-Van Laere syndrome (BVVLS [MIM 211530]) is a rare neurological disorder characterized by infancy onset sensorineural deafness and ponto-bulbar palsy. Mutations in SLC52A3 (formerly C20orf54), coding for riboflavin transporter 2 (hRFT2), have been identified as the molecular genetic correlate in several individuals with BVVLS. Exome sequencing of just one single case revealed that compound heterozygosity for two pathogenic mutations in the SLC52A2 gene coding for riboflavin transporter 3 (hRFT3), another member of the riboflavin transporter family, is also associated with BVVLS. Overexpression studies confirmed that the gene products of both mutant alleles have reduced riboflavin transport activities. While mutations in SLC52A3 cause decreased plasma riboflavin levels, concordant with a role of SLC52A3 in riboflavin uptake from food, the SLC52A2-mutant individual had normal plasma riboflavin concentrations, a finding in line with a postulated function of SLC52A2 in riboflavin uptake from blood into target cells. Our results contribute to the understanding of human riboflavin metabolism and underscore its role in the pathogenesis of BVVLS, thereby providing a rational basis for a high-dose riboflavin treatment. PMID:22864630

  3. First description of phosphofructokinase deficiency in spain: identification of a novel homozygous missense mutation in the PFKM gene

    PubMed Central

    Vives-Corrons, Joan-Lluis; Koralkova, Pavla; Grau, Josep M.; Mañú Pereira, Maria del Mar; Van Wijk, Richard

    2013-01-01

    Phosphofructokinase deficiency is a very rare autosomal recessive disorder, which belongs to group of rare inborn errors of metabolism called glycogen storage disease. Here we report on a new mutation in the phosphofructokinase (PFK) gene PFKM identified in a 65-years-old woman who suffered from lifelong intermittent muscle weakness and painful spasms of random occurrence, episodic dark urines, and slight haemolytic anemia. After ruling out the most common causes of chronic haemolytic anemia, the study of a panel of 24 enzyme activities showed a markedly decreased PFK activity in red blood cells (RBCs) from the patient. DNA sequence analysis of the PFKM gene subsequently revealed a novel homozygous mutation: c.926A>G; p.Asp309Gly. This mutation is predicted to severely affect enzyme catalysis thereby accounting for the observed enzyme deficiency. This case represents a prime example of classical PFK deficiency and is the first reported case of this very rare red blood cell disorder in Spain. PMID:24427140

  4. A novel missense mutation in the mouse hairless gene causes irreversible hair loss: genetic and molecular analyses of Hr m1Enu.

    PubMed

    Nam, YoonYi; Kim, Jeong Ki; Cha, Dal-Sun; Cho, Jae-Woo; Cho, Kyu-Hyuk; Yoon, SeokJoo; Yoon, Jong-Bok; Oh, Yang-Seok; Suh, Jun-Gyo; Han, Sang-Seop; Song, Chang-Woo; Yoon, SungJoo Kim

    2006-04-01

    A novel autosomal recessive mutant was produced using N-ethyl-N-nitrosourea mutagenesis. The characteristics of the mutant mice included progressive irreversible hair loss within a month of birth, wrinkled skin, and long curved nails. Linkage analysis revealed that the causative gene is linked to D14Mit193 on chromosome 14. Sequence analysis of the complete cDNA of the candidate gene, hairless (Hr), identified a homozygous G-to-T transition at nucleotide 3572, leading to the substitution of glycine by tryptophan, designated Gly960Trp. This missense mutation occurs in the vicinity of repression domain 3 of the hairless protein (HR). This allele was named Hr(m1Enu). The relative amounts of Hr mRNA and HR protein determined by real-time PCR and Western blot analyses, respectively, were slightly elevated in the mutant mice. Quantitative real-time PCR analysis revealed the increased expression of Kc1 and Vdr in the mutant mice, whereas the expression of Nrs1 and Krtap16-6 was decreased. These results suggest that the Gly960Trp substitution in HR protein in Hr(m1Enu) mice may alter the function of HR as a transcriptional corepressor. PMID:16455232

  5. Effect of liver fatty acid binding protein (FABP) T94A missense mutation on plasma lipoprotein responsiveness to treatment with fenofibrate.

    PubMed

    Brouillette, Charles; Bossé, Yohan; Pérusse, Louis; Gaudet, Daniel; Vohl, Marie-Claude

    2004-01-01

    Fenofibrate, a peroxisome proliferated activated receptor alpha (PPARalpha) agonist, has been shown to decrease plasma triglyceride (TG) and increase plasma high-density lipoprotein (HDL) cholesterol levels despite a large interindividual variation in the response. Fenofibrate-activated PPARalpha binds to a DNA sequence element termed PPAR response element (PPRE) present in regulatory regions of target genes. A PPRE has been identified in the proximal 5' flanking region of the gene encoding the liver fatty acid binding protein (LFABP). LFABP is a small cytosolic protein of 14 kDa present in the liver and the intestine and is a member of the superfamily of the fatty acid binding proteins (FABPs). FABPs play a role in the solubilization of long-chain fatty acids (LCFAs) and their CoA-ester to various intracellular organelles. FABPs serves as intracellular acceptors of LCFAs, and they may also have an impact in ligand-dependent transactivation of PPARs in trafficking LCFAs to the nucleus. Since PPARs are known to regulate the transcription of many genes involved in lipid metabolism, the importance of LFABP in fatty acid uptake has to be considered. The aim of this study was to verify whether genetic variations in the LFABP gene may impact on plasma lipoprotein/lipid levels in the fasting state as well as on the response to a lipid-lowering therapy with fenofibrate on plasma lipids and obesity variables. We also wanted to verify whether the presence of the PPARalpha L162V mutation interacts with genetic variants in LFABP gene. To achieve this goal, we first determined the genomic structure of the human LFABP gene and then designed intronic primers to sequence the coding regions, all exon-intron splicing boundaries, and the promoter region of the gene in 24 patients showing divergent plasma lipoprotein/lipid response to fenofibrate. Sequence analysis revealed the presence of a T94A missense mutation in exon 3. Interspecies comparison revealed that threonine 94 is

  6. A hyperexcitability phenotype in mouse trigeminal sensory neurons expressing the R192Q Cacna1a missense mutation of familial hemiplegic migraine type-1.

    PubMed

    Hullugundi, S K; Ansuini, A; Ferrari, M D; van den Maagdenberg, A M J M; Nistri, A

    2014-04-25

    Missense mutation R192Q in the CACNA1A gene causes familial hemiplegic migraine type-1 (FHM1), a monogenic subtype of migraine with aura. Using knock-in (KI) gene targeting we introduced this mutation into the mouse gene and generated a transgenic mouse model to investigate basic mechanisms of migraine pathophysiology. While FHM1 R192Q KI trigeminal ganglia were previously shown to exhibit constitutive up-regulation of ATP-gated P2X3 receptors, little is known about the firing properties of trigeminal sensory neurons, which convey nociceptive inputs to higher brain centers. We patch-clamped trigeminal sensory neurons to search for differences in firing properties between wildtype (WT) and KI cells in culture. Although various subclasses of trigeminal neurons were observed with respect to their firing patterns evoked by intracellular current injection, their distribution among WT and KI cells was similar with only small differences in rheobase or input resistance values. However, when neurons were excited by either α,β-methyl-ATP to stimulate P2X3 receptors or capsaicin to activate transient receptor potential vanilloid (TRPV1) receptors, the firing threshold in KI neurons was significantly lowered and followed by a larger number of spikes. Activation by α,β-methyl-ATP was associated with a transient cluster of action potentials, while capsaicin elicited more persistent firing. Using α,β-methyl-ATP or capsaicin, two functional classes of WT or KI neurons were distinguished according to the first spike latency, which suggests that a subgroup of neurons may be indirectly activated, probably via crosstalk between neurons and satellite glial cells. Thus, our results are consistent with reported facilitated trigeminal pain behavior of FHM1 R192Q KI mice. PMID:24583041

  7. GM1 gangliosidosis and Morquio B disease: expression analysis of missense mutations affecting the catalytic site of acid beta-galactosidase.

    PubMed

    Hofer, Doris; Paul, Karl; Fantur, Katrin; Beck, Michael; Bürger, Friederike; Caillaud, Catherine; Fumic, Ksenija; Ledvinova, Jana; Lugowska, Agnieszka; Michelakakis, Helen; Radeva, Briguita; Ramaswami, Uma; Plecko, Barbara; Paschke, Eduard

    2009-08-01

    Alterations in GLB1, the gene coding for acid beta-D-galactosidase (beta-Gal), can result in GM1 gangliosidosis (GM1), a neurodegenerative disorder, or in Morquio B disease (MBD), a phenotype with dysostosis multiplex and normal central nervous system (CNS) function. While most MBD patients carry a common allele, c.817TG>CT (p.W273L), only few of the >100 mutations known in GM1 can be related to a certain phenotype. In 25 multiethnic patients with GM1 or MBD, 11 missense mutations were found as well as one novel insertion and a transversion causing aberrant gene products. Except c.602G>A (p.R201H) and two novel alleles, c.592G>T (p.D198Y) and c.1189C>G (p.P397A), all mutants resulted in significantly reduced beta-Gal activities (<10% of normal) upon expression in COS-1 cells. Although c.997T>C (p.Y333H) expressed 3% of normal activity, the mutant protein was localized in the lysosomal-endosomal compartment. A homozygous case presented with late infantile GM1, while a heterozygous, juvenile case carried p.Y333H together with p.R201H. This allele, recently found in homozygous MBD, gives rise to rough endoplasmic reticulum (RER)-located beta-Gal precursors. Thus, unlike classical MBD, the phenotype of heterozygotes carrying p.R201H may rather be determined by poorly active, properly transported products of the counter allele than by the mislocalized p.R201H precursors. PMID:19472408

  8. Pathologic and phenotypic alterations in a mouse expressing a connexin47 missense mutation that causes Pelizaeus-Merzbacher-like disease in humans.

    PubMed

    Tress, Oliver; Maglione, Marta; Zlomuzica, Armin; May, Dennis; Dicke, Nikolai; Degen, Joachim; Dere, Ekrem; Kettenmann, Helmut; Hartmann, Dieter; Willecke, Klaus

    2011-07-01

    Gap junction channels are intercellular conduits that allow diffusional exchange of ions, second messengers, and metabolites. Human oligodendrocytes express the gap junction protein connexin47 (Cx47), which is encoded by the GJC2 gene. The autosomal recessive mutation hCx47M283T causes Pelizaeus-Merzbacher-like disease 1 (PMLD1), a progressive leukodystrophy characterized by hypomyelination, retarded motor development, nystagmus, and spasticity. We introduced the human missense mutation into the orthologous position of the mouse Gjc2 gene and inserted the mCx47M282T coding sequence into the mouse genome via homologous recombination in embryonic stem cells. Three-week-old homozygous Cx47M282T mice displayed impaired rotarod performance but unchanged open-field behavior. 10-15-day-old homozygous Cx47M282T and Cx47 null mice revealed a more than 80% reduction in the number of cells participating in glial networks after biocytin injections into oligodendrocytes in sections of corpus callosum. Homozygous expression of mCx47M282T resulted in reduced MBP expression and astrogliosis in the cerebellum of ten-day-old mice which could also be detected in Cx47 null mice of the same age. Three-month-old homozygous Cx47M282T mice exhibited neither altered open-field behavior nor impaired rotarod performance anymore. Adult mCx47M282T expressing mice did not show substantial myelin alterations, but homozygous Cx47M282T mice, additionally deprived of connexin32, which is also expressed in oligodendrocytes, died within six weeks after birth and displayed severe myelin defects accompanied by astrogliosis and activated microglia. These results strongly suggest that PMLD1 is caused by the loss of Cx47 channel function that results in impaired panglial coupling in white matter tissue. PMID:21750683

  9. A missense mutation in TMEM67 causes Meckel-Gruber syndrome type 3 (MKS3): a family from China

    PubMed Central

    Zhang, Manli; Cheng, Jing; Liu, Aijun; Wang, Longxia; Xiong, Lihua; Chen, Meixia; Sun, Yi; Li, Jianzhong; Lu, Yu; Yuan, Huijun; Li, Yali; Lu, Yanping

    2015-01-01

    Meckel-Gruber syndrome (MKS) is a lethal autosomal recessive condition characterized by renal cysts and variably associated features, including developmental anomalies of the central nervous system (typically encephalocele), hepatic ductal dysplasia and cysts, and polydactyly. Genetic heterogeneity has been demonstrated at eleven loci, MKS1-11. Here, we present the clinical and molecular characteristics of a Chinese MKS3 family with occipital encephalocele and kidney enlargement. DNA sequencing of affected fetuses revealed a homozygous c.1645C>T substitution in exon 16 of TMEM67, leading to a p.R549C substitution in meckelin. The R549 residue is highly conserved across human, rat, mouse, zebrafish, chicken, wolf and platypus genomes. Hha I restriction analysis demonstrated that the c.1645C>T mutation was absent in 200 unrelated control chromosomes of Chinese background, supporting the hypothesis that it represents causative mutation, not rare polymorphism. Our data provide additional molecular and clinical information for establishing a better genotype-phenotype understanding of MKS. PMID:26191240

  10. A missense mutation in TMEM67 causes Meckel-Gruber syndrome type 3 (MKS3): a family from China.

    PubMed

    Zhang, Manli; Cheng, Jing; Liu, Aijun; Wang, Longxia; Xiong, Lihua; Chen, Meixia; Sun, Yi; Li, Jianzhong; Lu, Yu; Yuan, Huijun; Li, Yali; Lu, Yanping

    2015-01-01

    Meckel-Gruber syndrome (MKS) is a lethal autosomal recessive condition characterized by renal cysts and variably associated features, including developmental anomalies of the central nervous system (typically encephalocele), hepatic ductal dysplasia and cysts, and polydactyly. Genetic heterogeneity has been demonstrated at eleven loci, MKS1-11. Here, we present the clinical and molecular characteristics of a Chinese MKS3 family with occipital encephalocele and kidney enlargement. DNA sequencing of affected fetuses revealed a homozygous c.1645C>T substitution in exon 16 of TMEM67, leading to a p.R549C substitution in meckelin. The R549 residue is highly conserved across human, rat, mouse, zebrafish, chicken, wolf and platypus genomes. Hha I restriction analysis demonstrated that the c.1645C>T mutation was absent in 200 unrelated control chromosomes of Chinese background, supporting the hypothesis that it represents causative mutation, not rare polymorphism. Our data provide additional molecular and clinical information for establishing a better genotype-phenotype understanding of MKS. PMID:26191240

  11. Destabilizing missense mutations in the tumour suppressor protein p53 enhance its ubiquitination in vitro and in vivo

    PubMed Central

    Shimizu, Harumi; Saliba, David; Wallace, Maura; Finlan, Lee; Langridge-Smith, Patrick R. R.; Hupp, Ted R.

    2006-01-01

    p53 ubiquitination catalysed by MDM2 (murine double minute clone 2 oncoprotein) provides a biochemical assay to dissect stages in E3-ubiquitin-ligase-catalysed ubiquitination of a conformationally flexible protein. A mutant form of p53 (p53F270A) containing a mutation in the second MDM2-docking site in the DNA-binding domain of p53 (F270A) is susceptible to modification of long-lived and high-molecular-mass covalent adducts in vivo. Mutant F270A is hyperubiquitinated in cells as defined by immunoprecipitation and immunoblotting with an anti-ubiquitin antibody. Transfection of His-tagged ubiquitin along with p53R175H or p53F270A also results in selective hyperubiquitination in cells under conditions where wild-type p53 is refractory to covalent modification. The extent of mutant p53R175H or p53F270A unfolding in cells as defined by exposure of the DO-12 epitope correlates with the extent of hyperubiquitination, suggesting a link between substrate conformation and E3 ligase function. The p53F270A:6KR chimaeric mutant (where 6KR refers to the simultaneous mutation of lysine residues at positions 370, 372, 373, 381, 382 and 386 to arginine) maintains the high-molecular-mass covalent adducts and is modified in an MDM2-dependent manner. Using an in vitro ubiquitination system, mutant p53F270A and the p53F270A:6KR chimaeric mutant is also subject to hyperubiquitination outwith the C-terminal domain, indicating direct recognition of the mutant p53 conformation by (a) factor(s) in the cell-free ubiquitination system. These data identify an in vitro and in vivo assay with which to dissect how oligomeric protein conformational alterations are linked to substrate ubiquitination in cells. This has implications for understanding the recognition of misfolded proteins during aging and in human diseases such as cancer. PMID:16579792

  12. A de novo missense mutation in ZMYND11 is associated with global developmental delay, seizures, and hypotonia.

    PubMed

    Moskowitz, Abby M; Belnap, Newell; Siniard, Ashley L; Szelinger, Szabolcs; Claasen, Ana M; Richholt, Ryan F; De Both, Matt; Corneveaux, Jason J; Balak, Chris; Piras, Ignazio S; Russell, Megan; Courtright, Amanda L; Rangasamy, Sampath; Ramsey, Keri; Craig, David W; Narayanan, Vinodh; Huentelman, Matt J; Schrauwen, Isabelle

    2016-09-01

    Recently, mutations in the zinc finger MYND-type containing 11 (ZMYND11) gene were identified in patients with autism spectrum disorders, intellectual disability, aggression, and complex neuropsychiatric features, supporting that this gene is implicated in 10p15.3 microdeletion syndrome. We report a novel de novo variant in the ZMYND11 gene (p.Ser421Asn) in a patient with a complex neurodevelopmental phenotype. The patient is a 24-yr-old Caucasian/Filipino female with seizures, global developmental delay, sensorineural hearing loss, hypotonia, dysmorphic features, and other features including a happy disposition and ataxic gait similar to Angelman syndrome. In addition, this patient had uncommon features including eosinophilic esophagitis and multiple, severe allergies not described in similar ZMYND11 cases. This new case further supports the association of ZMYND11 with autistic-like phenotypes and suggests that ZMYND11 should be included in the list of potentially causative candidate genes in cases with complex neurodevelopmental phenotypes. PMID:27626064

  13. A de novo missense mutation in ZMYND11 is associated with global developmental delay, seizures, and hypotonia

    PubMed Central

    Moskowitz, Abby M.; Belnap, Newell; Siniard, Ashley L.; Szelinger, Szabolcs; Claasen, Ana M.; Richholt, Ryan F.; De Both, Matt; Corneveaux, Jason J.; Balak, Chris; Piras, Ignazio S.; Russell, Megan; Courtright, Amanda L.; Rangasamy, Sampath; Ramsey, Keri; Craig, David W.; Narayanan, Vinodh; Huentelman, Matt J.; Schrauwen, Isabelle

    2016-01-01

    Recently, mutations in the zinc finger MYND-type containing 11 (ZMYND11) gene were identified in patients with autism spectrum disorders, intellectual disability, aggression, and complex neuropsychiatric features, supporting that this gene is implicated in 10p15.3 microdeletion syndrome. We report a novel de novo variant in the ZMYND11 gene (p.Ser421Asn) in a patient with a complex neurodevelopmental phenotype. The patient is a 24-yr-old Caucasian/Filipino female with seizures, global developmental delay, sensorineural hearing loss, hypotonia, dysmorphic features, and other features including a happy disposition and ataxic gait similar to Angelman syndrome. In addition, this patient had uncommon features including eosinophilic esophagitis and multiple, severe allergies not described in similar ZMYND11 cases. This new case further supports the association of ZMYND11 with autistic-like phenotypes and suggests that ZMYND11 should be included in the list of potentially causative candidate genes in cases with complex neurodevelopmental phenotypes. PMID:27626064

  14. A Pedigree with c.179 Cytosine to Threonine Missense Mutation of SLC12A3 Gene Presenting Gitelman's Syndrome

    PubMed Central

    Kim, Yaerim; Kang, Seong Sik; Park, Woo Yeong; Jin, Kyubok; Kim, Dae-Kwang

    2016-01-01

    A 42-year-old man came to the hospital presenting chest discomfort and general weakness. He had come to the hospital with the same symptoms 3 months ago and 12 years prior. His laboratory test showed hypokalemia, hypomagnesemia and hypocalciuria. The arterial blood gas analysis showed hypochloremic metabolic alkalosis. He had an ultrasonography guided renal biopsy, the result was normal at light microscopy and immunofluorescence microscopy. However, a special stain for Na-Cl cotransporter was weakly expressed compared with the control. The patient and his family underwent genetic sequencing about the SLC12A3 gene. He had a homozygous mutation in the 179th nucleotide of Exon 1 on the SLC12A3 gene (p.Thr60Met) and his parents and sisters were diagnosed as carrier state of Gitelman's syndrome (GS). GS is an inherited tubular disorder which presents mild hypokalemia, hypomagnesemia and hypocalciuria. Since the symptoms and laboratory results are not severe, it can go unnoticed by physicians. Herein we present a family with GS, diagnosed by genetic sequencing. PMID:27453715

  15. A missense mutation in the human liver/bone/kidney alkaline phosphatase gene causing a lethal form of hypophosphatasia.

    PubMed Central

    Weiss, M J; Cole, D E; Ray, K; Whyte, M P; Lafferty, M A; Mulivor, R A; Harris, H

    1988-01-01

    Hypophosphatasia is an inherited disorder characterized by defective bone mineralization and a deficiency of serum and tissue liver/bone/kidney alkaline phosphatase (L/B/K ALP) activity. Clinical severity is variable, ranging from death in utero (due to severe rickets) to pathologic fractures first presenting in adult life. Affected siblings, however, are phenotypically similar. Severe forms of the disease are inherited in an autosomal recessive fashion; heterozygotes often show reduced serum ALP activity. The specific gene defects in hypophosphatasia are unknown but are thought to occur either at the L/B/K ALP locus or within another gene that regulates L/B/K ALP expression. We used the polymerase chain reaction to examine L/B/K ALP cDNA from a patient with a perinatal (lethal) form of the disease. We observed a guanine-to-adenine transition in nucleotide 711 of the cDNA that converts alanine-162 of the mature enzyme to threonine. The affected individual, whose parents are second cousins, is homozygous for the mutant allele. Introduction of this mutation into an otherwise normal cDNA by site-directed mutagenesis abolishes the expression of active enzyme, demonstrating that a defect in the L/B/K ALP gene results in hypophosphatasia and that the enzyme is, therefore, essential for normal skeletal mineralization. Images PMID:3174660

  16. A Missense Mutation in SLC45A2 Is Associated with Albinism in Several Small Long Haired Dog Breeds.

    PubMed

    Wijesena, Hiruni R; Schmutz, Sheila M

    2015-01-01

    Homozygosity for a large deletion in the solute carrier family 45, member 2 (SLC45A2) gene causes oculocutaneous albinism (OCA) in the Doberman Pinscher breed. An albino Lhasa Apso did not have this g.27141_31223del (CanFam2) deletion in her SLC45A2 sequence. Therefore, SLC45A2 was investigated in this female Lhasa Apso to search for other possible variants that caused her albinism. The albino Lhasa Apso was homozygous for a nonsynonymous substitution in the seventh exon, a c.1478G>A base change that resulted in a glycine to aspartic acid substitution (p.G493D). This mutation was not found in a wolf, a coyote, or any of the 15 other Lhasa Apso dogs or 32 other dogs of breeds related to the Lhasa Apso. However, an albino Pekingese, 2 albino Pomeranians, and an albino mixed breed dog that was small and long haired were also homozygous for the 493D allele. The colored puppies of the albino Lhasa Apso and the colored dam of the 2 albino Pomeranians were heterozygous for this allele. However, an albino Pug was homozygous for the 493G allele and therefore although we suggest the 493D allele causes albinism when homozygous in several small, long haired dog breeds, it does not explain all albinism in dogs. A variant effect prediction for the albino Lhasa Apso confirms that p.G493D is a deleterious substitution, and a topology prediction for SLC45A2 suggests that the 11th transmembrane domain where the 493rd amino acid was located, has an altered structure. PMID:25790827

  17. GM2 gangliosidosis associated with a HEXA missense mutation in Japanese Chin dogs: a potential model for Tay Sachs disease.

    PubMed

    Sanders, Douglas N; Zeng, Rong; Wenger, David A; Johnson, Gary S; Johnson, Gayle C; Decker, Jared E; Katz, Martin L; Platt, Simon R; O'Brien, Dennis P

    2013-01-01

    GM2 gangliosidosis is a fatal lysosomal storage disease caused by a deficiency of β-hexosaminidase (EC 3.2.1.52). There are two major isoforms of the enzyme: hexosaminidase A composed of an α and a β subunit (encoded by HEXA and HEXB genes, respectively); and, hexosaminidase B composed of two β subunits. Hexosaminidase A requires an activator protein encoded by GM2A to catabolize GM2 ganglioside, but even in the absence of the activator protein, it can hydrolyze the synthetic substrates commonly used to assess enzyme activity. GM2 gangliosidosis has been reported in Japanese Chin dogs, and we identified the disease in two related Japanese Chin dogs based on clinical signs, histopathology and elevated brain GM2 gangliosides. As in previous reports, we found normal or elevated hexosaminidase activity when measured with the synthetic substrates. This suggested that the canine disease is analogous to human AB variant of G(M2) gangliosidosis, which results from mutations in GM2A. However, only common neutral single nucleotide polymorphisms were found upon sequence analysis of the canine ortholog of GM2A from the affected Japanese Chins. When the same DNA samples were used to sequence HEXA, we identified a homozygous HEXA:c967G>A transition which predicts a p.E323K substitution. The glutamyl moiety at 323 is known to make an essential contribution to the active site of hexosaminidase A, and none of the 128 normal Japanese Chins and 92 normal dogs of other breeds that we tested was homozygous for HEXA:c967A. Thus it appears that the HEXA:c967G>A transition is responsible for the GM2 gangliosidosis in Japanese Chins. PMID:23266199

  18. KIF1A missense mutations in SPG30, an autosomal recessive spastic paraplegia: distinct phenotypes according to the nature of the mutations

    PubMed Central

    Klebe, Stephan; Lossos, Alexander; Azzedine, Hamid; Mundwiller, Emeline; Sheffer, Ruth; Gaussen, Marion; Marelli, Cecilia; Nawara, Magdalena; Carpentier, Wassila; Meyer, Vincent; Rastetter, Agnès; Martin, Elodie; Bouteiller, Delphine; Orlando, Laurent; Gyapay, Gabor; El-Hachimi, Khalid H; Zimmerman, Batel; Gamliel, Moriya; Misk, Adel; Lerer, Israela; Brice, Alexis; Durr, Alexandra; Stevanin, Giovanni

    2012-01-01

    The hereditary spastic paraplegias (HSPs) are a clinically and genetically heterogeneous group of neurodegenerative diseases characterised by progressive spasticity in the lower limbs. The nosology of autosomal recessive forms is complex as most mapped loci have been identified in only one or a few families and account for only a small percentage of patients. We used next-generation sequencing focused on the SPG30 chromosomal region on chromosome 2q37.3 in two patients from the original linked family. In addition, wide genome scan and candidate gene analysis were performed in a second family of Palestinian origin. We identified a single homozygous mutation, p.R350G, that was found to cosegregate with the disease in the SPG30 kindred and was absent in 970 control chromosomes while affecting a strongly conserved amino acid at the end of the motor domain of KIF1A. Homozygosity and linkage mapping followed by mutation screening of KIF1A allowed us to identify a second mutation, p.A255V, in the second family. Comparison of the clinical features with the nature of the mutations of all reported KIF1A families, including those reported recently with hereditary sensory and autonomic neuropathy, suggests phenotype–genotype correlations that may help to understand the mechanisms involved in motor neuron degeneration. We have shown that mutations in the KIF1A gene are responsible for SPG30 in two autosomal recessive HSP families. In published families, the nature of the KIF1A mutations seems to be of good predictor of the underlying phenotype and vice versa. PMID:22258533

  19. Missense Mutation of Brain Derived Neurotrophic Factor (BDNF) Alters Neurocognitive Performance in Patients with Mild Traumatic Brain Injury: A Longitudinal Study

    PubMed Central

    Ahmad-Annuar, Azlina; Ramli, Norlisah; Waran, Vicknes; Chinna, Karuthan; Bondi, Mark William; Delano-Wood, Lisa; Ganesan, Dharmendra

    2016-01-01

    The predictability of neurocognitive outcomes in patients with traumatic brain injury is not straightforward. The extent and nature of recovery in patients with mild traumatic brain injury (mTBI) are usually heterogeneous and not substantially explained by the commonly known demographic and injury-related prognostic factors despite having sustained similar injuries or injury severity. Hence, this study evaluated the effects and association of the Brain Derived Neurotrophic Factor (BDNF) missense mutations in relation to neurocognitive performance among patients with mTBI. 48 patients with mTBI were prospectively recruited and MRI scans of the brain were performed within an average 10.1 (SD 4.2) hours post trauma with assessment of their neuropsychological performance post full Glasgow Coma Scale (GCS) recovery. Neurocognitive assessments were repeated again at 6 months follow-up. The paired t-test, Cohen’s d effect size and repeated measure ANOVA were performed to delineate statistically significant differences between the groups [wildtype G allele (Val homozygotes) vs. minor A allele (Met carriers)] and their neuropsychological performance across the time point (T1 = baseline/ admission vs. T2 = 6th month follow-up). Minor A allele carriers in this study generally performed more poorly on neuropsychological testing in comparison wildtype G allele group at both time points. Significant mean differences were observed among the wildtype group in the domains of memory (M = -11.44, SD = 10.0, p = .01, d = 1.22), executive function (M = -11.56, SD = 11.7, p = .02, d = 1.05) and overall performance (M = -6.89 SD = 5.3, p = .00, d = 1.39), while the minor A allele carriers showed significant mean differences in the domains of attention (M = -11.0, SD = 13.1, p = .00, d = .86) and overall cognitive performance (M = -5.25, SD = 8.1, p = .01, d = .66).The minor A allele carriers in comparison to the wildtype G allele group, showed considerably lower scores at admission and

  20. Rare key functional domain missense substitutions in MRE11A, RAD50, and NBN contribute to breast cancer susceptibility: results from a Breast Cancer Family Registry case-control mutation-screening study

    PubMed Central

    2014-01-01

    Introduction The MRE11A-RAD50-Nibrin (MRN) complex plays several critical roles related to repair of DNA double-strand breaks. Inherited mutations in the three components predispose to genetic instability disorders and the MRN genes have been implicated in breast cancer susceptibility, but the underlying data are not entirely convincing. Here, we address two related questions: (1) are some rare MRN variants intermediate-risk breast cancer susceptibility alleles, and if so (2) do the MRN genes follow a BRCA1/BRCA2 pattern wherein most susceptibility alleles are protein-truncating variants, or do they follow an ATM/CHEK2 pattern wherein half or more of the susceptibility alleles are missense substitutions? Methods Using high-resolution melt curve analysis followed by Sanger sequencing, we mutation screened the coding exons and proximal splice junction regions of the MRN genes in 1,313 early-onset breast cancer cases and 1,123 population controls. Rare variants in the three genes were pooled using bioinformatics methods similar to those previously applied to ATM, BRCA1, BRCA2, and CHEK2, and then assessed by logistic regression. Results Re-analysis of our ATM, BRCA1, and BRCA2 mutation screening data revealed that these genes do not harbor pathogenic alleles (other than modest-risk SNPs) with minor allele frequencies >0.1% in Caucasian Americans, African Americans, or East Asians. Limiting our MRN analyses to variants with allele frequencies of <0.1% and combining protein-truncating variants, likely spliceogenic variants, and key functional domain rare missense substitutions, we found significant evidence that the MRN genes are indeed intermediate-risk breast cancer susceptibility genes (odds ratio (OR) = 2.88, P = 0.0090). Key domain missense substitutions were more frequent than the truncating variants (24 versus 12 observations) and conferred a slightly higher OR (3.07 versus 2.61) with a lower P value (0.029 versus 0.14). Conclusions These data establish

  1. Case report: A novel apolipoprotein A-I missense mutation apoA-I (Arg149Ser)Boston associated with decreased lecithin-cholesterol acyltransferase activation and cellular cholesterol efflux.

    PubMed

    Anthanont, Pimjai; Asztalos, Bela F; Polisecki, Eliana; Zachariah, Benoy; Schaefer, Ernst J

    2015-01-01

    We report a novel heterozygous apolipoprotein A-I (apoA-I) missense mutation (c.517C>A, p.Arg149Ser, designated as apoA-IBoston) in a 67-year-old woman and her 2 sons, who had mean serum high-density lipoprotein (HDL) cholesterol, apoA-I, and apoA-I in very large α-1 HDL that were 10%, 35%, and 16% of normal, respectively (all P < .05). The percentage of HDL cholesterol in the esterified form was also significantly (P < .05) reduced to 52% of control values. Cholesteryl ester tranfer protein (CETP) activity was normal. The mean global, adenosine triphosphate (ATP)-binding cassette transporter A1 and scavenger receptor B type I-mediated cellular cholesterol efflux capacity in apoB-depleted serum from affected family members were 41%, 37%, 47%, 54%, and 48% of control values, respectively (all P < .05). lecithin-cholesterol acyltransferase (LCAT) activity in plasma was 71% of controls, whereas in the cell-based assay, it was 73% of control values (P < .05). The data indicate that this novel apoA-I missense is associated with markedly decreased levels of HDL cholesterol and very large α-1 HDL, as well as decreased serum cellular cholesterol efflux and LCAT activity, but not with premature coronary heart disease, similar to other apoA-I mutations that have been associated with decreased LCAT activity. PMID:26073399

  2. [beta]-hexosaminidase isozymes from cells cotransfected with [alpha] and [beta] cDNA constructs: Analysis of the [alpha]-subunit missense mutation associated with the adult form of Tay-Sachs disease

    SciTech Connect

    Brown, C.A.; Mahuran, D.J. )

    1993-08-01

    In vitro mutagenesis and transient expression in COS cells has been used to associate a missense mutation with a clinical or biochemical phenotype. Mutations affecting the [alpha]-subunit of [beta]-hexosaminidase A ([alpha][beta]) (E.C.3.2.1.52) result in Tay-Sachs disease. Because hexosaminidase A is heterodimeric, analysis of [alpha]-chain mutations is not straightforward. The authors examine three approaches utilizing previously identified mutations affecting [alpha]-chain folding. These involve transfection of (1) the [alpha] cDNA alone; (2) a [beta] cDNA construct encoding a [beta]-subunit substituted at a position homologous to that of the [alpha]-subunit, and (3) both [alpha] and [beta] cDNAs. The latter two procedures amplified residual activity levels over that of patient samples, an effect not previously found with mutations affecting an [open quotes]active[close quotes] [alpha]Arg residue. This effect may help to discriminate between protein-folding and active-site mutations. The authors conclude that, with proper controls, the latter method of cotransfection can be used to evaluate the effects and perhaps to predict the clinical course of some [alpha]-chain mutations. Using this technique, they demonstrate that the adult-onset Tay-Sachs mutation, [alpha]Gly[yields]Ser[sup 269], does not directly affect [alpha][beta] dimerization but exerts an indirect effect on the dimer through destabilizing the folded [alpha]-subunit at physiological temperatures. Two other [alpha] mutations linked to more severe phenotypes appear to inhibit the initial folding of the subunit. 36 refs., 2 figs., 5 tabs.

  3. Powdery Mildew Resistance Conferred by Loss of the ENHANCED DISEASE RESISTANCE1 Protein Kinase Is Suppressed by a Missense Mutation in KEEP ON GOING, a Regulator of Abscisic Acid Signaling1[W][OA

    PubMed Central

    Wawrzynska, Anna; Christiansen, Katy M.; Lan, Yinan; Rodibaugh, Natalie L.; Innes, Roger W.

    2008-01-01

    Loss-of-function mutations in the Arabidopsis (Arabidopsis thaliana) ENHANCED DISEASE RESISTANCE1 (EDR1) gene confer enhanced resistance to infection by powdery mildew (Golovinomyces cichoracearum). EDR1 encodes a protein kinase, but its substrates and the pathways regulated by EDR1 are unknown. To identify components of the EDR1 signal transduction pathway(s), we conducted a forward genetic screen for mutations that suppressed edr1-mediated disease resistance. Genetic mapping and cloning of one of these suppressor mutations revealed a recessive missense mutation in the KEEP ON GOING gene (KEG; At5g13530), which we designated keg-4. KEG encodes a multidomain protein that includes a RING E3 ligase domain, a kinase domain, ankyrin repeats, and HERC2-like repeats. The KEG protein has previously been shown to have ubiquitin ligase activity and to negatively regulate protein levels of the transcription factor ABCISIC ACID INSENSITIVE5. KEG mRNA levels were found to be 3-fold higher in edr1 mutant plants compared to wild type. Loss-of-function mutations in KEG are seedling lethal and are hypersensitive to glucose and abscisic acid (ABA). The keg-4 mutation, in contrast, conferred resistance to 6% glucose and suppressed edr1-mediated hypersensitivity to ABA, suggesting that the keg-4 mutation suppresses ABA signaling by altering KEG function. Several ABA-responsive genes were found to be further up-regulated in the edr1 mutant following ABA treatment, and this up-regulation was suppressed by the keg-4 mutation. We conclude that edr1-mediated resistance to powdery mildew is mediated, in part, by enhanced ABA signaling. PMID:18815384

  4. A-TWinnipeg: Pathogenesis of rare ATM missense mutation c.6200C>A with decreased protein expression and downstream signaling, early-onset dystonia, cancer, and life-threatening radiotoxicity

    PubMed Central

    Nakamura, Kotoka; Fike, Francesca; Haghayegh, Sara; Saunders-Pullman, Rachel; Dawson, Angelika J; Dörk, Thilo; Gatti, Richard A

    2014-01-01

    We studied 10 Mennonite patients who carry the c.6200C>A missense mutation (p.A2067D) in the ATM gene, all of whom exhibited a phenotypic variant of ataxia-telangiectasia (A-T) that is characterized by early-onset dystonia and late-onset mild ataxia, as previously described. This report provides the pathogenetic evidence for this mutation on cellular functions. Several patients have developed cancer and subsequently experienced life-threatening adverse reactions to radiation (radiotoxicity) and/or chemotherapy. As the c.6200C>A mutation is, thus far, unique to the Mennonite population and is always associated with the same haplotype or haplovariant, it was important to rule out any possible confounding DNA variant on the same haplotype. Lymphoblastoid cells derived from Mennonite patients expressed small amounts of ATM protein, which had no autophosphorylation activity at ATM Ser1981, and trace-to-absent transphosphorylation of downstream ATM targets. A-T lymphoblastoid cells stably transfected with ATM cDNA which had been mutated for c.6200C>A did not show a detectable amount of ATM protein. The same stable cell line with mutated ATM cDNA also showed a trace-to-absent transphosphorylation of downstream ATM targets SMC1pSer966 and KAP1pSer824. From these results, we conclude that c.6200A is the disease-causing ATM mutation on this haplotype. The presence of at least trace amounts of ATM kinase activity on some immunoblots may account for the late-onset, mild ataxia of these patients. The cause of the dystonia remains unclear. Because this dystonia-ataxia phenotype is often encountered in the Mennonite population in association with cancer and adverse reactions to chemotherapy, an early diagnosis is important. PMID:25077176

  5. Autosomal Dominant Polycystic Kidney Disease (ADPKD) in an Italian family carrying a novel nonsense mutation and two missense changes in exons 44 and 45 of the PKD1 gene

    SciTech Connect

    Rossetti, S.; Bresin, E.; Corra, S.

    1996-10-16

    Sixty-seven Italian patients with autosomal dominant polycystic kidney disease (ADPKD) were screened for mutations in the 3{prime} unique region of the PKD1 gene, using heteroduplex DNA analysis. Novel aberrant bands were detected in 3 patients from the same family. DNA sequencing showed a C to T transition in exon 44 (C12269T), resulting in a premature stop codon (R4020X), predicted to impair the synthesis of the putative intracytoplasmic C-terminus tail of the PKD1 protein, polycystin. The mutation also generates a novel DdeI restriction site, and the abnormal restriction pattern was observed both on genomic DNA and on cDNA from the affected relatives, indicating that this is indeed the pathogenetic molecular lesion. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on lymphocyte mRNA showed that the mutant transcript is normally present and stable. No aberrantly spliced mRNAs were detected. Interestingly, the mutant PKD1 chromosome in this family also bears two missense mutations downstream (A12341G and C12384T), not found in the other ADPKD families studied. 19 refs., 4 figs.

  6. An overlapping phenotype of Osteogenesis imperfecta and Ehlers-Danlos syndrome due to a heterozygous mutation in COL1A1 and biallelic missense variants in TNXB identified by whole exome sequencing.

    PubMed

    Mackenroth, Luisa; Fischer-Zirnsak, Björn; Egerer, Johannes; Hecht, Jochen; Kallinich, Tilmann; Stenzel, Werner; Spors, Birgit; von Moers, Arpad; Mundlos, Stefan; Kornak, Uwe; Gerhold, Kerstin; Horn, Denise

    2016-04-01

    Osteogenesis imperfecta (OI) and Ehlers-Danlos syndrome (EDS) are variable genetic disorders that overlap in different ways [Cole 1993; Grahame 1999]. Here, we describe a boy presenting with severe muscular hypotonia, multiple fractures, and joint hyperflexibility, features that are compatible with mild OI and hypermobility type EDS, respectively. By whole exome sequencing, we identified both a COL1A1 mutation (c.4006-1G > A) inherited from the patient's mildly affected mother and biallelic missense variants in TNXB (p.Val1213Ile, p.Gly2592Ser). Analysis of cDNA showed that the COL1A1 splice site mutation led to intron retention causing a frameshift (p.Phe1336Valfs*72). Type 1 collagen secretion by the patient's skin fibroblasts was reduced. Immunostaining of a muscle biopsy obtained from the patient revealed a clear reduction of tenascin-X in the extracellular matrix compared to a healthy control. These findings imply that the combination of the COL1A1 mutation with the TNXB variants might cause the patient's unique phenotype. PMID:26799614

  7. A novel missense mutation p.L76P in the GJB2 gene causing nonsyndromic recessive deafness in a Brazilian family.

    PubMed

    Batissoco, A C; Auricchio, M T B M; Kimura, L; Tabith-Junior, A; Mingroni-Netto, R C

    2009-02-01

    Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessive hearing loss in many countries. We report here on a novel point mutation in GJB2, p.L76P (c.227C>T), in compound heterozygosity with a c.35delG mutation, in two Brazilian sibs, one presenting mild and the other profound nonsyndromic neurosensorial hearing impairment. Their father, who carried a wild-type allele and a p.L76P mutation, had normal hearing. The mutation leads to the substitution of leucine (L) by proline (P) at residue 76, an evolutionarily conserved position in Cx26 as well as in other connexins. This mutation is predicted to affect the first extracellular domain (EC1) or the second transmembrane domain (TM2). EC1 is important for connexon-connexon interaction and for the control of channel voltage gating. The segregation of the c.227C>T (p.L76P) mutation together with c.35delG in this family indicates a recessive mode of inheritance. The association between the p.L76P mutation and hearing impairment is further supported by its absence in a normal hearing control group of 100 individuals, 50 European-Brazilians and 50 African-Brazilians. PMID:19274344

  8. Fulminant neurological deterioration in a neonate with Leigh syndrome due to a maternally transmitted missense mutation in the mitochondrial ND3 gene

    SciTech Connect

    Leshinsky-Silver, E.; E-mail: leshinsky@wolfson.health.gov.il; Lev, D.; Tzofi-Berman, Z.; Cohen, S.; Saada, A.; Yanoov-Sharav, M.; Gilad, E.; Lerman-Sagie, T.

    2005-08-26

    Leigh syndrome can result from both nuclear and mitochondrial DNA defects. Mutations in complex V genes of the respiratory chain were considered until recently as the most frequent cause for mitochondrial inherited Leigh syndrome, while gene defects in complex I were related to recessive Leigh syndrome. Recently few reports of mutations in the mitochondrial-encoded complex I subunit genes causing Leigh syndrome have been reported. We describe a 1-month-old baby who acutely deteriorated, with abrupt onset of brainstem dysfunction, due to basal ganglia lesions extending to the brainstem. A muscle biopsy demonstrated complex I deficiency. Subsequent analysis of the mitochondrial genome revealed a homoplastic T10191C mutation in the ND3 gene (in blood and muscle), resulting in a substitution of serine to proline. Hair root analysis revealed a 50% mutant load, reflecting heteroplasmy in early embryonic stages. The mutation was also detected in his mother (5%). Western blot analysis revealed a decrease of the 20 kDa subunit (likely ND6) and of the 30 kDa subunit (NDUFA9), which is probably due to instability attributed to the inability to form subcomplexes with ND3. This is the first description of infantile Leigh syndrome due to a maternally transmitted T10191C substitution in ND3 and not due to a de novo mutation. This mutation is age and tissue dependent and therefore may not be amenable to prenatal testing.

  9. Insights Into the Pathogenicity of Rare Missense GCK Variants From the Identification and Functional Characterization of Compound Heterozygous and Double Mutations Inherited in Cis

    PubMed Central

    Beer, Nicola L.; Osbak, Kara K.; van de Bunt, Martijn; Tribble, Nicholas D.; Steele, Anna M.; Wensley, Kirsty J.; Edghill, Emma L.; Colcough, Kevin; Barrett, Amy; Valentínová, Lucia; Rundle, Jana K.; Raimondo, Anne; Grimsby, Joseph; Ellard, Sian; Gloyn, Anna L.

    2012-01-01

    OBJECTIVE To demonstrate the importance of using a combined genetic and functional approach to correctly interpret a genetic test for monogenic diabetes. RESEARCH DESIGN AND METHODS We identified three probands with a phenotype consistent with maturity-onset diabetes of the young (MODY) subtype GCK-MODY, in whom two potential pathogenic mutations were identified: [R43H/G68D], [E248 K/I225M], or [G261R/D217N]. Allele-specific PCR and cosegregation were used to determine phase. Single and double mutations were kinetically characterized. RESULTS The mutations occurred in cis (double mutants) in two probands and in trans in one proband. Functional studies of all double mutants revealed inactivating kinetics. The previously reported GCK-MODY mutations R43H and G68D were inherited from an affected father and unaffected mother, respectively. Both our functional and genetic studies support R43H as the cause of GCK-MODY and G68D as a neutral rare variant. CONCLUSIONS These data highlight the need for family/functional studies, even for previously reported pathogenic mutations. PMID:22611063

  10. Targeted next-generation sequencing identification of a novel missense mutation of the SKIV2L gene in a patient with trichohepatoenteric syndrome.

    PubMed

    Zheng, Bixia; Pan, Jian; Jin, Yu; Wang, Chunli; Liu, Zhifeng

    2016-09-01

    Trichohepatoenteric syndrome (THES) is a rare autosomal, recessively inherited disorder. Mutations in the tetratricopeptide repeat domain 37 (TTC37) gene and the superkiller viralicidic activity 2‑like (SKIV2L) gene have been identified to cause THES. The present study reported a case of a Chinese boy, who presented clinically with intrauterine growth retardation, intractable diarrhea, facial dysmorphism, abnormal scalp hair shafts, immune disorders and liver involvement. Targeted next‑generation sequencing and Sanger DNA sequencing showed compound heterozygous mutations of the SKIV2L gene. The present study was the first, to the best of our knowledge, to report a case of a boy with THES resulting from compound heterozygous mutations of the SKIV2L gene in China. Target sequence capture combined with high‑throughput next‑generation sequencing technologies have shown to be effective methods for the molecular genetic assessment of rare inherited disorders. PMID:27431780

  11. A novel heterozygous missense mutation (His127Arg) in a family with inherited cross-reacting material positive factor XI deficiency.

    PubMed

    Castaman, Giancarlo; Giacomelli, Sofia H; Tagliaferri, Annarita; Rodeghiero, Francesco

    2013-09-01

    Factor XI (FXI) deficiency is an autosomal inherited coagulation disorder, characterized by an inconsistent bleeding tendency, mainly associated with injury or surgery. Although most of the F11 gene mutations cause a true quantitative deficiency of FXI (cross-reacting material-negative, CRM-), very few variants characterized by a qualitative abnormality resulting in a discrepant FXI activity/FXI antigen ratio (CRM positive, CRM+) have been reported. We describe here a novel CRM+ mutation (His127Arg) identified in an asymptomatic woman from Indonesia and in her two sons. PMID:23571684

  12. Missense mutation in immunodeficient patients shows the multifunctional roles of coiled-coil domain 3 (CC3) in STIM1 activation.

    PubMed

    Maus, Mate; Jairaman, Amit; Stathopulos, Peter B; Muik, Martin; Fahrner, Marc; Weidinger, Carl; Benson, Melina; Fuchs, Sebastian; Ehl, Stephan; Romanin, Christoph; Ikura, Mitsuhiko; Prakriya, Murali; Feske, Stefan

    2015-05-12

    Store-operated Ca(2+) entry (SOCE) is a universal Ca(2+) influx pathway that is important for the function of many cell types. SOCE occurs upon depletion of endoplasmic reticulum (ER) Ca(2+) stores and relies on a complex molecular interplay between the plasma membrane (PM) Ca(2+) channel ORAI1 and the ER Ca(2+) sensor stromal interaction molecule (STIM) 1. Patients with null mutations in ORAI1 or STIM1 genes present with severe combined immunodeficiency (SCID)-like disease. Here, we describe the molecular mechanisms by which a loss-of-function STIM1 mutation (R429C) in human patients abolishes SOCE. R429 is located in the third coiled-coil (CC3) domain of the cytoplasmic C terminus of STIM1. Mutation of R429 destabilizes the CC3 structure and alters the conformation of the STIM1 C terminus, thereby releasing a polybasic domain that promotes STIM1 recruitment to ER-PM junctions. However, the mutation also impairs cytoplasmic STIM1 oligomerization and abolishes STIM1-ORAI1 interactions. Thus, despite its constitutive localization at ER-PM junctions, mutant STIM1 fails to activate SOCE. Our results demonstrate multifunctional roles of the CC3 domain in regulating intra- and intermolecular STIM1 interactions that control (i) transition of STIM1 from a quiescent to an active conformational state, (ii) cytoplasmic STIM1 oligomerization, and (iii) STIM1-ORAI1 binding required for ORAI1 activation. PMID:25918394

  13. Transient neonatal diabetes due to a missense mutation (E227K) in the gene encoding the ATP-sensitive potassium channel (KCNJ11).

    PubMed

    Martins, Luísa; Lourenço, Rita; Maia, Ana Lúcia; Maciel, Paula; Monteiro, Maria Isabel; Pacheco, Lucinda; Anselmo, João; César, Rui; Gomes, Maria Fernanda

    2015-10-01

    Neonatal diabetes is a monogenic form of diabetes. Herein, we report on a newborn presenting diabetic ketoacidosis at 17 days of life. A KCNJ11 mutation was identified. In such cases, insulin can be replaced by sulfonylurea with a successful metabolic control, as an example of how molecular diagnosis may influence the clinical management of the disorder. PMID:26509005

  14. Missense mutation in immunodeficient patients shows the multifunctional roles of coiled-coil domain 3 (CC3) in STIM1 activation

    PubMed Central

    Maus, Mate; Jairaman, Amit; Stathopulos, Peter B.; Muik, Martin; Fahrner, Marc; Weidinger, Carl; Benson, Melina; Fuchs, Sebastian; Ehl, Stephan; Romanin, Christoph; Ikura, Mitsuhiko; Prakriya, Murali; Feske, Stefan

    2015-01-01

    Store-operated Ca2+ entry (SOCE) is a universal Ca2+ influx pathway that is important for the function of many cell types. SOCE occurs upon depletion of endoplasmic reticulum (ER) Ca2+ stores and relies on a complex molecular interplay between the plasma membrane (PM) Ca2+ channel ORAI1 and the ER Ca2+ sensor stromal interaction molecule (STIM) 1. Patients with null mutations in ORAI1 or STIM1 genes present with severe combined immunodeficiency (SCID)-like disease. Here, we describe the molecular mechanisms by which a loss-of-function STIM1 mutation (R429C) in human patients abolishes SOCE. R429 is located in the third coiled-coil (CC3) domain of the cytoplasmic C terminus of STIM1. Mutation of R429 destabilizes the CC3 structure and alters the conformation of the STIM1 C terminus, thereby releasing a polybasic domain that promotes STIM1 recruitment to ER–PM junctions. However, the mutation also impairs cytoplasmic STIM1 oligomerization and abolishes STIM1–ORAI1 interactions. Thus, despite its constitutive localization at ER–PM junctions, mutant STIM1 fails to activate SOCE. Our results demonstrate multifunctional roles of the CC3 domain in regulating intra- and intermolecular STIM1 interactions that control (i) transition of STIM1 from a quiescent to an active conformational state, (ii) cytoplasmic STIM1 oligomerization, and (iii) STIM1–ORAI1 binding required for ORAI1 activation. PMID:25918394

  15. Compound heterozygosity for a novel hemizygous missense mutation and a partial deletion affecting the catalytic core of the H2O2-generating enzyme DUOX2 associated with transient congenital hypothyroidism.

    PubMed

    Hoste, Candice; Rigutto, Sabrina; Van Vliet, Guy; Miot, Françoise; De Deken, Xavier

    2010-04-01

    Dual oxidases (DUOX) 1 and 2 are components of the thyroid H(2)O(2)-generating system. H(2)O(2) is used by thyroperoxidase to oxidize iodide for thyroid hormonogenesis. Mutations in the DUOX2 gene have been described in transient and permanent congenital thyroid dyshormonogenesis. We report here a novel genetic defect causing congenital hypothyroidism in a French-Canadian patient. At neonatal screening, the patient had high TSH and low total T(4) levels. (99m)Tc scan showed a normally shaped orthotopic but mildly enlarged thyroid gland, suggesting dyshormonogenesis. Thyroxine treatment was given from 1 month to 17 years, after which it was stopped for re-evaluation and the patient remained euthyroid. The transient congenital hypothyroidism phenotype prompted us to screen for mutations in DUOX2 and DUOXA2 genes using the PCR-amplified direct sequencing method. We found complete inactivation of DUOX2 caused by a partial genomic deletion of one allele inherited from the mother associated with a paternally inherited missense mutation (c.4552G>A, p.Gly1518Ser). The deleted fragment encompasses the entire COOH-terminal end which is responsible for the NADPH-oxidase activity. The Gly1518Ser DUOX2 protein is expressed at the cell surface of transfected cells albeit at low level, but it is non-functional. This study provides further evidence that the permanent or transient nature of congenital hypothyroidism is not directly related to the number of inactivated DUOX2 alleles, suggesting the existence of other pathophysiological factors. PMID:20187165

  16. Selective expression of Parkinson's disease-related Leucine-rich repeat kinase 2 G2019S missense mutation in midbrain dopaminergic neurons impairs dopamine release and dopaminergic gene expression.

    PubMed

    Liu, Guoxiang; Sgobio, Carmelo; Gu, Xinglong; Sun, Lixin; Lin, Xian; Yu, Jia; Parisiadou, Loukia; Xie, Chengsong; Sastry, Namratha; Ding, Jinhui; Lohr, Kelly M; Miller, Gary W; Mateo, Yolanda; Lovinger, David M; Cai, Huaibin

    2015-09-15

    Preferential dysfunction/degeneration of midbrain substantia nigra pars compacta (SNpc) dopaminergic (DA) neurons contributes to the main movement symptoms manifested in Parkinson's disease (PD). Although the Leucine-rich repeat kinase 2 (LRRK2) G2019S missense mutation (LRRK2 G2019S) is the most common causative genetic factor linked to PD, the effects of LRRK2 G2019S on the function and survival of SNpc DA neurons are poorly understood. Using a binary gene expression system, we generated transgenic mice expressing either wild-type human LRRK2 (WT mice) or the LRRK2 G2019S mutation (G2019S mice) selectively in the midbrain DA neurons. Here we show that overexpression of LRRK2 G2019S did not induce overt motor abnormalities or substantial SNpc DA neuron loss. However, the LRRK2 G2019S mutation impaired dopamine homeostasis and release in aged mice. This reduction in dopamine content/release coincided with the degeneration of DA axon terminals and decreased expression of DA neuron-enriched genes tyrosine hydroxylase (TH), vesicular monoamine transporter 2, dopamine transporter and aldehyde dehydrogenase 1. These factors are responsible for dopamine synthesis, transport and degradation, and their expression is regulated by transcription factor paired-like homeodomain 3 (PITX3). Levels of Pitx3 mRNA and protein were similarly decreased in the SNpc DA neurons of aged G2019S mice. Together, these findings suggest that PITX3-dependent transcription regulation could be one of the many potential mechanisms by which LRRK2 G2019S acts in SNpc DA neurons, resulting in downregulation of its downstream target genes critical for dopamine homeostasis and release. PMID:26123485

  17. A syndrome of female pseudohermaphrodism, hypergonadotropic hypogonadism, and multicystic ovaries associated with missense mutations in the gene encoding aromatase (P450arom)

    SciTech Connect

    Conte, F.A.; Grumbach, M.M.; Ito, Y.; Fisher, C.R.; Simpson, E.R.

    1994-06-01

    The authors report the features of a new syndrome of aromatase deficiency due to molecular defects in the CYP19 (P450arom) gene in a 46,XX female. At birth, the patient presented with a nonadrenal form of female pseudohermaphrodism. At 17 months of age, laparotomy revealed normal female internal genital structures; the histological appearance of the ovaries was normal. FSH concentrations were markedly elevated at 9.4 ng/mL LER 869, and estrone and estradiol levels were undetectable (<37 pmol/L). By 14 yr of age, she had failed to exhibit breast development. The clitoris has enlarged to 4 x 2 cm, and pubic hair was Tanner stage IV. The plasma concentration of testosterone was elevated at 3294 pmol/L, as was androstenedione at 9951 pmol/L. Plasma estradiol levels were below 37 pmol/L. ACTH and dexamethasone tests indicated a nonadrenal source of testosterone and androstenedione. Plasma gonadotropin levels were in the castrate range. Pelvic sonography and magnetic resonance imaging showed multiple 4- to 6-cm ovarian cysts bilaterally. Despite increased circulating androgens and clitoral growth, the bone age was 10 yr at chronologic age 14 2/12 yr. Estrogen replacement therapy resulted in a growth spurt, breast development, menarche, suppression of gonadotropin levels, and resolution of the cysts. The clinical findings suggested the diagnosis of P450arom deficiency. Analyses of genomic DNA from ovarian fibroblasts demonstrated two single base changes in the coding region of the P450arom gene, one at 1303 basepairs (C-T), R435C, and the other at 1310 basepairs (G-A), C437Y, in exon 10. The molecular genetic studies indicate that the patient is a compound heterozygote for these mutations. Expression of these mutations showed that the R435C mutation had 1.1% the activity of the wild-type P450arom enzyme, whereas the C437Y mutation demonstrated no activity. 32 refs., 6 figs., 2 tabs.

  18. Integrating In Silico Prediction Methods, Molecular Docking, and Molecular Dynamics Simulation to Predict the Impact of ALK Missense Mutations in Structural Perspective

    PubMed Central

    Priya Doss, C. George; Chen, Luonan

    2014-01-01

    Over the past decade, advancements in next generation sequencing technology have placed personalized genomic medicine upon horizon. Understanding the likelihood of disease causing mutations in complex diseases as pathogenic or neutral remains as a major task and even impossible in the structural context because of its time consuming and expensive experiments. Among the various diseases causing mutations, single nucleotide polymorphisms (SNPs) play a vital role in defining individual's susceptibility to disease and drug response. Understanding the genotype-phenotype relationship through SNPs is the first and most important step in drug research and development. Detailed understanding of the effect of SNPs on patient drug response is a key factor in the establishment of personalized medicine. In this paper, we represent a computational pipeline in anaplastic lymphoma kinase (ALK) for SNP-centred study by the application of in silico prediction methods, molecular docking, and molecular dynamics simulation approaches. Combination of computational methods provides a way in understanding the impact of deleterious mutations in altering the protein drug targets and eventually leading to variable patient's drug response. We hope this rapid and cost effective pipeline will also serve as a bridge to connect the clinicians and in silico resources in tailoring treatments to the patients' specific genotype. PMID:25054154

  19. Forced expression of desmin and desmin mutants in cultured cells: impact of myopathic missense mutations in the central coiled-coil domain on network formation.

    PubMed

    Bär, Harald; Kostareva, Anna; Sjöberg, Gunnar; Sejersen, Thomas; Katus, Hugo A; Herrmann, Harald

    2006-05-15

    We recently demonstrated that inherited disease-causing mutations clustered in the alpha-helical coiled-coil "rod" domain of the muscle-specific intermediate filament (IF) protein desmin display a wide range of inhibitory effects on regular in vitro assembly. In these studies, we showed that individual mutations exhibited phenotypes that were not, with respect to the severity of interference, predictable by our current knowledge of the structural design of IF proteins. Moreover, the behavior of some mutated proteins in a standard tissue culture cell expression system was found to be even more complex. Here, we systematically investigate the behavior of these disease mutants in four different cell types: three not containing desmin or the related IF protein vimentin and the standard fibroblast line 3T3, which has an extensive vimentin system. The ability of the mutants to form filaments in the vimentin-free cells varies considerably, and only the mutants forming IFs in vitro generate extended filamentous networks. Furthermore, these latter mutants integrate into the 3T3 vimentin network but all the others do not. Instead, they cause the endogenous network of 3T3 vimentin to reorganize into perinuclear bundles. In addition, most of these assembly-deficient mutant desmins completely segregate from the vimentin system. Instead, the small round to fibrillar particles formed distribute independently throughout the cytoplasm as well as between the collapsed vimentin filament arrays in the perinuclear area. PMID:16519886

  20. Missense mutations in PBP2A Affecting ceftaroline susceptibility detected in epidemic hospital-acquired methicillin-resistant Staphylococcus aureus clonotypes ST228 and ST247 in Western Switzerland archived since 1998.

    PubMed

    Kelley, William L; Jousselin, Ambre; Barras, Christine; Lelong, Emmanuelle; Renzoni, Adriana

    2015-04-01

    The development and maintenance of an arsenal of antibiotics is a major health care challenge. Ceftaroline is a new cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA); however, no reports concerning MRSA ceftaroline susceptibility have been reported in Switzerland. We tested the in vitro activity of ceftaroline against an archived set of 60 MRSA strains from the University Hospital of Geneva collected from 1994 to 2003. Our results surprisingly revealed ceftaroline-resistant strains (MIC, >1 μg/ml in 40/60 strains; EUCAST breakpoints, susceptible [S], ≤1 μg/ml; resistant [R], >1 μg/ml) were present from 1998 to 2003. The detected resistant strains predominantly belonged to sequence type 228 (ST228) (South German clonotype) but also to ST247 (Iberian clonotype). A sequence analysis of these strains revealed missense mutations in the penicillin-binding protein 2A (PBP2A) allosteric domain (N146K or E239K and N146K-E150K-G246E). The majority of our ST228 PBP2A mutations (N146K or E150K) were distinct from ST228 PBP2A allosteric domain mutations (primarily E239K) recently described for MRSA strains collected in Thailand and Spain during the 2010 Assessing Worldwide Antimicrobial Resistance Evaluation (AWARE) global surveillance program. We also found that similar allosteric domain PBP2A mutations (N146K) correlated with ceftaroline resistance in an independent external ST228 MRSA set obtained from the nearby University Hospital of Lausanne, Lausanne, Switzerland, collected from 2003 to 2008. Thus, ceftaroline resistance was observed in our archived strains (including two examples of an MIC of 4 µg/ml for the Iberian ST247 clonotype with the triple mutation N146K/E150K/G246E), at least as far back as 1998, considerably predating the commercial introduction of ceftaroline. Our results reinforce the notion that unknown parameters can potentially exert selective pressure on PBP2A that can subsequently modulate ceftaroline

  1. A 19-year-old man with relapsing bilateral pneumothorax, hemoptysis, and intrapulmonary cavitary lesions diagnosed with vascular Ehlers-Danlos syndrome and a novel missense mutation in COL3A1.

    PubMed

    Abrahamsen, Bjørg J; Kulseth, Mari Ann; Paus, Benedicte

    2015-05-01

    A 19-year-old sportsman experienced a right-sided pneumothorax and hemoptysis after having had an intermittent cough and blood-tinged sputum for 2 months. A chest CT scan revealed small cavitary lesions in both lungs. The relapsing pneumothorax was treated with a chest tube twice, as well as surgically after the second relapse. Two months after surgery, the patient developed a cough, fever, and high C-reactive protein levels. At that time, large consolidations had developed in the right lung, while the left lung subsequently collapsed due to pneumothorax. The patient's physical appearance and anamnestic information led us to suspect a genetic connective tissue disease. A sequencing analysis of the COL3A1 gene identified a novel, de novo missense mutation that confirmed the diagnosis of vascular Ehlers-Danlos syndrome (EDS). This atypical presentation of vascular EDS with intrathoracic complications shows that enhanced awareness is required and demonstrates the usefulness of the genetic analyses that are clinically available for several hereditary connective tissue disorders. PMID:25940258

  2. Homozygous Missense N629D hERG (KCNH2) Potassium Channel Mutation Causes Developmental Defects in the Right Ventricle and its Outflow Tract and Embryonic Lethality

    PubMed Central

    Teng, Guo Qi; Zhao, Xian; Lees-Miller, James P.; Quinn, F. Russell; Li, Pin; Rancourt, Derrick E.; London, Barry; Cross, James C.; Duff, Henry J.

    2009-01-01

    Loss-of-function mutations in the human ERG1 potassium channel (hERG1) frequently underlie the Long QT2 Syndrome. The role of the ERG potassium channel in cardiac development was elaborated in an in vivo model of a homozygous, loss of function, LQT2 Syndrome mutation. The hERG N629D mutation was introduced into the orthologous mouse gene, mERG, by homologous recombination in mouse embryonic stem cells. Intact homozygous embryos showed abrupt cessation of the heart beat. N629D/N629D embryos die in utero by E11.5. Their developmental defects include: altered looping architecture; poorly developed bulbus cordis; distorted aortic sac and branchial arches. N629D/N629D myocytes from E9.5 embryos manifested complete loss of IKr function, depolarized resting potential, prolonged action potential duration (LQT), failure to repolarize and propensity to oscillatory arrhythmias. N629D/N629D myocytes manifest calcium oscillations and increased SR Ca+2 – content. While the N629D/N629D protein is synthesized it is mainly located intracellularly; whereas +/+ mERG protein is mainly in plasmalemma. N629D/N629D embryos show robust apoptosis in cranio-facial regions, particularly in the first branchial arch and to a lesser extent in the cardiac outflow tract. Since deletion of Hand2 produces apoptosis, in similar regions and with a similar final developmental phenotype, Hand2 expression was evaluated. Robust decrease in Hand2 expression was observed in the secondary heart field in N629D/N629D embryos. In conclusion, loss of IKr function in N629D/N629D cardiovascular system leads to defects in cardiac ontogeny in the first branchial arch, outflow tract and the right ventricle. PMID:18948620

  3. Oral and Craniofacial Manifestations and Two Novel Missense Mutations of the NTRK1 Gene Identified in the Patient with Congenital Insensitivity to Pain with Anhidrosis

    PubMed Central

    Bai, Yudi; Liu, Xin; Yu, Ping; Xue, Yang; Ma, Shufang; Wei, Kewen; Jin, Yan; Wen, Lingying; Xuan, Kun

    2013-01-01

    Congenital insensitivity to pain with anhidrosis (CIPA) is a rare inherited disorder of the peripheral nervous system resulting from mutations in neurotrophic tyrosine kinase receptor 1 gene (NTRK1), which encodes the high-affinity nerve growth factor receptor TRKA. Here, we investigated the oral and craniofacial manifestations of a Chinese patient affected by autosomal-recessive CIPA and identified compound heterozygosity in the NTRK1 gene. The affected boy has multisystemic disorder with lack of reaction to pain stimuli accompanied by self-mutilation behavior, the inability to sweat leading to defective thermoregulation, and mental retardation. Oral and craniofacial manifestations included a large number of missing teeth, nasal malformation, submucous cleft palate, severe soft tissue injuries, dental caries and malocclusion. Histopathological evaluation of the skin sample revealed severe peripheral nerve fiber loss as well as mild loss and absent innervation of sweat glands. Ultrastructural and morphometric studies of a shed tooth revealed dental abnormalities, including hypomineralization, dentin hypoplasia, cementogenesis defects and a dysplastic periodontal ligament. Genetic analysis revealed a compound heterozygosity- c.1561T>C and c.2057G>A in the NTRK1 gene. This report extends the spectrum of NTRK1 mutations observed in patients diagnosed with CIPA and provides additional insight for clinical and molecular diagnosis. PMID:23799134

  4. Degenerative myelopathy associated with a missense mutation in the superoxide dismutase 1 (SOD1) gene progresses to peripheral neuropathy in Pembroke Welsh corgis and boxers.

    PubMed

    Shelton, G Diane; Johnson, Gayle C; O'Brien, Dennis P; Katz, Martin L; Pesayco, Jill P; Chang, Brian J; Mizisin, Andrew P; Coates, Joan R

    2012-07-15

    Canine degenerative myelopathy (DM) is an adult-onset, fatal neurodegenerative disease with many similarities to an upper-motor-neuron-onset form of human amyotrophic lateral sclerosis (ALS), that results from mutations in the superoxide dismutase (SOD1) gene. DM occurs in many dog breeds, including the Pembroke Welsh Corgi and Boxer. The initial upper motor neuron degeneration produces spastic paraparesis and affected dogs develop general proprioceptive ataxia in the pelvic limbs. Dog owners usually elect euthanasia when their dog becomes paraplegic. When euthanasia is delayed, lower motor neuron signs including ascending tetraparesis, flaccid paralysis and widespread muscle atrophy emerge. For this study, muscle and peripheral nerve specimens were evaluated at varying disease stages from DM-affected Pembroke Welsh Corgis and Boxers that were homozygous for the SOD1 mutation and had spinal cord histopathology consistent with DM. Comparisons were made with age- and breed-matched control dogs. Here we provide evidence that Pembroke Welsh Corgis and Boxers with chronic DM develop muscle atrophy consistent with denervation, peripheral nerve pathology consistent with an axonopathy, and to a lesser degree demyelination. Canine DM has been proposed as a potential spontaneous animal disease model of human ALS. The results of this study provide further support that canine DM recapitulates one form of the corresponding human disorder and should serve as a valuable animal model to develop therapeutic strategies. PMID:22542607

  5. Production of Transgenic Pigs with an Introduced Missense Mutation of the Bone Morphogenetic Protein Receptor Type IB Gene Related to Prolificacy.

    PubMed

    Zhao, Xueyan; Yang, Qiang; Zhao, Kewei; Jiang, Chao; Ren, Dongren; Xu, Pan; He, Xiaofang; Liao, Rongrong; Jiang, Kai; Ma, Junwu; Xiao, Shijun; Ren, Jun; Xing, Yuyun

    2016-07-01

    In the last few decades, transgenic animal technology has witnessed an increasingly wide application in animal breeding. Reproductive traits are economically important to the pig industry. It has been shown that the bone morphogenetic protein receptor type IB (BMPR1B) A746G polymorphism is responsible for the fertility in sheep. However, this causal mutation exits exclusively in sheep and goat. In this study, we attempted to create transgenic pigs by introducing this mutation with the aim to improve reproductive traits in pigs. We successfully constructed a vector containing porcine BMPR1B coding sequence (CDS) with the mutant G allele of A746G mutation. In total, we obtained 24 cloned male piglets using handmade cloning (HMC) technique, and 12 individuals survived till maturation. A set of polymerase chain reactions indicated that 11 of 12 matured boars were transgene-positive individuals, and that the transgenic vector was most likely disrupted during cloning. Of 11 positive pigs, one (No. 11) lost a part of the terminator region but had the intact promoter and the CDS regions. cDNA sequencing showed that the introduced allele (746G) was expressed in multiple tissues of transgene-positive offspring of No.11. Western blot analysis revealed that BMPR1B protein expression in multiple tissues of transgene-positive F1 piglets was 0.5 to 2-fold higher than that in the transgene-negative siblings. The No. 11 boar showed normal litter size performance as normal pigs from the same breed. Transgene-positive F1 boars produced by No. 11 had higher semen volume, sperm concentration and total sperm per ejaculate than the negative siblings, although the differences did not reached statistical significance. Transgene-positive F1 sows had similar litter size performance to the negative siblings, and more data are needed to adequately assess the litter size performance. In conclusion, we obtained 24 cloned transgenic pigs with the modified porcine BMPR1B CDS using HMC. c

  6. Production of Transgenic Pigs with an Introduced Missense Mutation of the Bone Morphogenetic Protein Receptor Type IB Gene Related to Prolificacy

    PubMed Central

    Zhao, Xueyan; Yang, Qiang; Zhao, Kewei; Jiang, Chao; Ren, Dongren; Xu, Pan; He, Xiaofang; Liao, Rongrong; Jiang, Kai; Ma, Junwu; Xiao, Shijun; Ren, Jun; Xing, Yuyun

    2016-01-01

    In the last few decades, transgenic animal technology has witnessed an increasingly wide application in animal breeding. Reproductive traits are economically important to the pig industry. It has been shown that the bone morphogenetic protein receptor type IB (BMPR1B) A746G polymorphism is responsible for the fertility in sheep. However, this causal mutation exits exclusively in sheep and goat. In this study, we attempted to create transgenic pigs by introducing this mutation with the aim to improve reproductive traits in pigs. We successfully constructed a vector containing porcine BMPR1B coding sequence (CDS) with the mutant G allele of A746G mutation. In total, we obtained 24 cloned male piglets using handmade cloning (HMC) technique, and 12 individuals survived till maturation. A set of polymerase chain reactions indicated that 11 of 12 matured boars were transgene-positive individuals, and that the transgenic vector was most likely disrupted during cloning. Of 11 positive pigs, one (No. 11) lost a part of the terminator region but had the intact promoter and the CDS regions. cDNA sequencing showed that the introduced allele (746G) was expressed in multiple tissues of transgene-positive offspring of No.11. Western blot analysis revealed that BMPR1B protein expression in multiple tissues of transgene-positive F1 piglets was 0.5 to 2-fold higher than that in the transgene-negative siblings. The No. 11 boar showed normal litter size performance as normal pigs from the same breed. Transgene-positive F1 boars produced by No. 11 had higher semen volume, sperm concentration and total sperm per ejaculate than the negative siblings, although the differences did not reached statistical significance. Transgene-positive F1 sows had similar litter size performance to the negative siblings, and more data are needed to adequately assess the litter size performance. In conclusion, we obtained 24 cloned transgenic pigs with the modified porcine BMPR1B CDS using HMC. c

  7. Exome sequencing identifies de novo gain of function missense mutation in KCND2 in identical twins with autism and seizures that slows potassium channel inactivation.

    PubMed

    Lee, Hane; Lin, Meng-chin A; Kornblum, Harley I; Papazian, Diane M; Nelson, Stanley F

    2014-07-01

    Numerous studies and case reports show comorbidity of autism and epilepsy, suggesting some common molecular underpinnings of the two phenotypes. However, the relationship between the two, on the molecular level, remains unclear. Here, whole exome sequencing was performed on a family with identical twins affected with autism and severe, intractable seizures. A de novo variant was identified in the KCND2 gene, which encodes the Kv4.2 potassium channel. Kv4.2 is a major pore-forming subunit in somatodendritic subthreshold A-type potassium current (ISA) channels. The de novo mutation p.Val404Met is novel and occurs at a highly conserved residue within the C-terminal end of the transmembrane helix S6 region of the ion permeation pathway. Functional analysis revealed the likely pathogenicity of the variant in that the p.Val404Met mutant construct showed significantly slowed inactivation, either by itself or after equimolar coexpression with the wild-type Kv4.2 channel construct consistent with a dominant effect. Further, the effect of the mutation on closed-state inactivation was evident in the presence of auxiliary subunits that associate with Kv4 subunits to form ISA channels in vivo. Discovery of a functionally relevant novel de novo variant, coupled with physiological evidence that the mutant protein disrupts potassium current inactivation, strongly supports KCND2 as the causal gene for epilepsy in this family. Interaction of KCND2 with other genes implicated in autism and the role of KCND2 in synaptic plasticity provide suggestive evidence of an etiological role in autism. PMID:24501278

  8. Exome sequencing identifies de novo gain of function missense mutation in KCND2 in identical twins with autism and seizures that slows potassium channel inactivation

    PubMed Central

    Lee, Hane; Lin, Meng-chin A.; Kornblum, Harley I.; Papazian, Diane M.; Nelson, Stanley F.

    2014-01-01

    Numerous studies and case reports show comorbidity of autism and epilepsy, suggesting some common molecular underpinnings of the two phenotypes. However, the relationship between the two, on the molecular level, remains unclear. Here, whole exome sequencing was performed on a family with identical twins affected with autism and severe, intractable seizures. A de novo variant was identified in the KCND2 gene, which encodes the Kv4.2 potassium channel. Kv4.2 is a major pore-forming subunit in somatodendritic subthreshold A-type potassium current (ISA) channels. The de novo mutation p.Val404Met is novel and occurs at a highly conserved residue within the C-terminal end of the transmembrane helix S6 region of the ion permeation pathway. Functional analysis revealed the likely pathogenicity of the variant in that the p.Val404Met mutant construct showed significantly slowed inactivation, either by itself or after equimolar coexpression with the wild-type Kv4.2 channel construct consistent with a dominant effect. Further, the effect of the mutation on closed-state inactivation was evident in the presence of auxiliary subunits that associate with Kv4 subunits to form ISA channels in vivo. Discovery of a functionally relevant novel de novo variant, coupled with physiological evidence that the mutant protein disrupts potassium current inactivation, strongly supports KCND2 as the causal gene for epilepsy in this family. Interaction of KCND2 with other genes implicated in autism and the role of KCND2 in synaptic plasticity provide suggestive evidence of an etiological role in autism. PMID:24501278

  9. A missense mutation in DCDC2 causes human recessive deafness DFNB66, likely by interfering with sensory hair cell and supporting cell cilia length regulation

    PubMed Central

    Grati, M'hamed; Chakchouk, Imen; Ma, Qi; Bensaid, Mariem; Desmidt, Alexandra; Turki, Nouha; Yan, Denise; Baanannou, Aissette; Mittal, Rahul; Driss, Nabil; Blanton, Susan; Farooq, Amjad; Lu, Zhongmin; Liu, Xue Zhong; Masmoudi, Saber

    2015-01-01

    Hearing loss is the most common sensory deficit in humans. We show that a point mutation in DCDC2 (DCDC2a), a member of doublecortin domain-containing protein superfamily, causes non-syndromic recessive deafness DFNB66 in a Tunisian family. Using immunofluorescence on rat inner ear neuroepithelia, DCDC2a was found to localize to the kinocilia of sensory hair cells and the primary cilia of nonsensory supporting cells. DCDC2a fluorescence is distributed along the length of the kinocilium with increased density toward the tip. DCDC2a-GFP overexpression in non-polarized COS7 cells induces the formation of long microtubule-based cytosolic cables suggesting a role in microtubule formation and stabilization. Deafness mutant DCDC2a expression in hair cells and supporting cells causes cilium structural defects, such as cilium branching, and up to a 3-fold increase in length ratios. In zebrafish, the ortholog dcdc2b was found to be essential for hair cell development, survival and function. Our results reveal DCDC2a to be a deafness gene and a player in hair cell kinocilia and supporting cell primary cilia length regulation likely via its role in microtubule formation and stabilization. PMID:25601850

  10. Immunisation against αIIbβ3 and αvβ3 in a type 1 variant of Glanzmann's thrombasthenia caused by a missense mutation Gly540Asp on β3.

    PubMed

    Wihadmadyatami, Hevi; Röder, Lida; Berghöfer, Heike; Bein, Gregor; Heidinger, Kathrin; Sachs, Ulrich J; Santoso, Sentot

    2016-08-01

    Treatment of bleeding in patients with Glanzmann's thrombasthenia (GT) can be hampered by iso-antibodies against the αIIbβ3 integrin, which cause rapid clearance of transfused donor platelets. Type 1 GT patients with a total absence of αIIbβ3 from the platelet surface are known to be susceptible to form such isoantibodies. In this study, we describe a type 1 GT patient with a missense mutation (Gly540Asn) located in the EGF3 domain of the β3 integrin subunit. Cotransfection analysis in CHO cells demonstrates total absence of αIIbβ3 from the surface, based on inappropriate αIIb maturation. The patient's serum was reactive with αIIbβ3 and αvβ3 integrins in a capture assay, when platelets and endothelial cells were used. Two specificities could be isolated from the patient's serum, anti-αIIbβ3 and anti-αvβ3 isoantibodies. Both specificities did not interfere with platelet aggregation. In contrast, isoantibodies against αvβ3, but not against αIIbβ3, were able to disturb endothelial cell adhesion onto vitronectin, triggered endothelial cell apoptosis and interfered with endothelial tube formation. This intriguing finding may explain more recently observed features of fetal/neonatal iso-immune thrombocytopenia in children from type 1 GT mothers with intracranial haemorrhage, which could be related to anti-endothelial activity of the maternal antibodies. In conclusion, we give evidence that two isoantibody entities exist in type 1 GT patients, which are unequivocally different, both in an immunological and functional sense. Further research on the clinical consequences of immunisation against αvβ3 is required, predominantly in GT patients of childbearing age. PMID:27098940

  11. The common missense mutation D489N in TRIM32 causing limb girdle muscular dystrophy 2H leads to loss of the mutated protein in knock-in mice resulting in a Trim32-null phenotype.

    PubMed

    Kudryashova, Elena; Struyk, Arie; Mokhonova, Ekaterina; Cannon, Stephen C; Spencer, Melissa J

    2011-10-15

    Mutations in tripartite motif protein 32 (TRIM32) are responsible for several hereditary disorders that include limb girdle muscular dystrophy type 2H (LGMD2H), sarcotubular myopathy (STM) and Bardet Biedl syndrome. Most LGMD2H mutations in TRIM32 are clustered in the NHL β-propeller domain at the C-terminus and are predicted to interfere with homodimerization. To get insight into TRIM32's role in the pathogenesis of LGMD2H and to create an accurate model of disease, we have generated a knock-in mouse (T32KI) carrying the c.1465G > A (p.D489N) mutation in murine Trim32 corresponding to the human LGMD2H/STM pathogenic mutation c.1459G > A (p.D487N). Our data indicate that T32KI mice have both a myopathic and a neurogenic phenotype, very similar to the one described in the Trim32-null mice that we created previously. Analysis of Trim32 gene expression in T32KI mice revealed normal mRNA levels, but a severe reduction in mutant TRIM32 (D489N) at the protein level. Our results suggest that the D489N pathogenic mutation destabilizes the protein, leading to its degradation, and results in the same mild myopathic and neurogenic phenotype as that found in Trim32-null mice. Thus, one potential mechanism of LGMD2H might be destabilization of mutated TRIM32 protein leading to a null phenotype. PMID:21775502

  12. In Silico Analysis of FMR1 Gene Missense SNPs.

    PubMed

    Tekcan, Akin

    2016-06-01

    The FMR1 gene, a member of the fragile X-related gene family, is responsible for fragile X syndrome (FXS). Missense single-nucleotide polymorphisms (SNPs) are responsible for many complex diseases. The effect of FMR1 gene missense SNPs is unknown. The aim of this study, using in silico techniques, was to analyze all known missense mutations that can affect the functionality of the FMR1 gene, leading to mental retardation (MR) and FXS. Data on the human FMR1 gene were collected from the Ensembl database (release 81), National Centre for Biological Information dbSNP Short Genetic Variations database, 1000 Genomes Browser, and NHLBI Exome Sequencing Project Exome Variant Server. In silico analysis was then performed. One hundred-twenty different missense SNPs of the FMR1 gene were determined. Of these, 11.66 % of the FMR1 gene missense SNPs were in highly conserved domains, and 83.33 % were in domains with high variety. The results of the in silico prediction analysis showed that 31.66 % of the FMR1 gene SNPs were disease related and that 50 % of SNPs had a pathogenic effect. The results of the structural and functional analysis revealed that although the R138Q mutation did not seem to have a damaging effect on the protein, the G266E and I304N SNPs appeared to disturb the interaction between the domains and affect the function of the protein. This is the first study to analyze all missense SNPs of the FMR1 gene. The results indicate the applicability of a bioinformatics approach to FXS and other FMR1-related diseases. I think that the analysis of FMR1 gene missense SNPs using bioinformatics methods would help diagnosis of FXS and other FMR1-related diseases. PMID:26880065

  13. KD4v: comprehensible knowledge discovery system for missense variant

    PubMed Central

    Luu, Tien-Dao; Rusu, Alin; Walter, Vincent; Linard, Benjamin; Poidevin, Laetitia; Ripp, Raymond; Moulinier, Luc; Muller, Jean; Raffelsberger, Wolfgang; Wicker, Nicolas; Lecompte, Odile; Thompson, Julie D.; Poch, Olivier; Nguyen, Hoan

    2012-01-01

    A major challenge in the post-genomic era is a better understanding of how human genetic alterations involved in disease affect the gene products. The KD4v (Comprehensible Knowledge Discovery System for Missense Variant) server allows to characterize and predict the phenotypic effects (deleterious/neutral) of missense variants. The server provides a set of rules learned by Induction Logic Programming (ILP) on a set of missense variants described by conservation, physico-chemical, functional and 3D structure predicates. These rules are interpretable by non-expert humans and are used to accurately predict the deleterious/neutral status of an unknown mutation. The web server is available at http://decrypthon.igbmc.fr/kd4v. PMID:22641855

  14. Disease-proportional proteasomal degradation of missense dystrophins

    PubMed Central

    Talsness, Dana M.; Belanto, Joseph J.; Ervasti, James M.

    2015-01-01

    The 427-kDa protein dystrophin is expressed in striated muscle where it physically links the interior of muscle fibers to the extracellular matrix. A range of mutations in the DMD gene encoding dystrophin lead to a severe muscular dystrophy known as Duchenne (DMD) or a typically milder form known as Becker (BMD). Patients with nonsense mutations in dystrophin are specifically targeted by stop codon read-through drugs, whereas out-of-frame deletions and insertions are targeted by exon-skipping therapies. Both treatment strategies are currently in clinical trials. Dystrophin missense mutations, however, cause a wide range of phenotypic severity in patients. The molecular and cellular consequences of such mutations are not well understood, and there are no therapies specifically targeting this genotype. Here, we have modeled two representative missense mutations, L54R and L172H, causing DMD and BMD, respectively, in full-length dystrophin. In vitro, the mutation associated with the mild phenotype (L172H) caused a minor decrease in tertiary stability, whereas the L54R mutation associated with a severe phenotype had a more dramatic effect. When stably expressed in mammalian muscle cells, the mutations caused steady-state decreases in dystrophin protein levels inversely proportional to the tertiary stability and directly caused by proteasomal degradation. Both proteasome inhibitors and heat shock activators were able to increase mutant dystrophin to WT levels, establishing the new cell lines as a platform to screen for potential therapeutics personalized to patients with destabilized dystrophin. PMID:26392559

  15. Disease-proportional proteasomal degradation of missense dystrophins.

    PubMed

    Talsness, Dana M; Belanto, Joseph J; Ervasti, James M

    2015-10-01

    The 427-kDa protein dystrophin is expressed in striated muscle where it physically links the interior of muscle fibers to the extracellular matrix. A range of mutations in the DMD gene encoding dystrophin lead to a severe muscular dystrophy known as Duchenne (DMD) or a typically milder form known as Becker (BMD). Patients with nonsense mutations in dystrophin are specifically targeted by stop codon read-through drugs, whereas out-of-frame deletions and insertions are targeted by exon-skipping therapies. Both treatment strategies are currently in clinical trials. Dystrophin missense mutations, however, cause a wide range of phenotypic severity in patients. The molecular and cellular consequences of such mutations are not well understood, and there are no therapies specifically targeting this genotype. Here, we have modeled two representative missense mutations, L54R and L172H, causing DMD and BMD, respectively, in full-length dystrophin. In vitro, the mutation associated with the mild phenotype (L172H) caused a minor decrease in tertiary stability, whereas the L54R mutation associated with a severe phenotype had a more dramatic effect. When stably expressed in mammalian muscle cells, the mutations caused steady-state decreases in dystrophin protein levels inversely proportional to the tertiary stability and directly caused by proteasomal degradation. Both proteasome inhibitors and heat shock activators were able to increase mutant dystrophin to WT levels, establishing the new cell lines as a platform to screen for potential therapeutics personalized to patients with destabilized dystrophin. PMID:26392559

  16. A Single Missense Mutation in a Coiled-Coil Domain of Escherichia coli Ribosomal Protein S2 Confers a Thermosensitive Phenotype That Can Be Suppressed by Ribosomal Protein S1

    PubMed Central

    Aseev, Leonid V.; Chugunov, Anton O.; Efremov, Roman G.

    2013-01-01

    Ribosomal protein S2 is an essential component of translation machinery, and its viable mutated variants conferring distinct phenotypes serve as a valuable tool in studying the role of S2 in translation regulation. One of a few available rpsB mutants, rpsB1, shows thermosensitivity and ensures enhanced expression of leaderless mRNAs. In this study, we identified the nature of the rpsB1 mutation. Sequencing of the rpsB1 allele revealed a G-to-A transition in the part of the rpsB gene which encodes a coiled-coil domain of S2. The resulting E132K substitution resides in a highly conserved site, TKKE, a so-called N-terminal capping box, at the beginning of the second alpha helix. The protruding coiled-coil domain of S2 is known to provide binding with 16S rRNA in the head of the 30S subunit and, in addition, to interact with a key mRNA binding protein, S1. Molecular dynamics simulations revealed a detrimental impact of the E132K mutation on the coiled-coil structure and thereby on the interactions between S2 and 16S rRNA, providing a clue for the thermosensitivity of the rpsB1 mutant. Using a strain producing a leaderless lacZ transcript from the chromosomal lac promoter, we demonstrated that not only the rpsB1 mutation generating S2/S1-deficient ribosomes but also the rpsA::IS10 mutation leading to partial deficiency in S1 alone increased translation efficiency of the leaderless mRNA by about 10-fold. Moderate overexpression of S1 relieved all these effects and, moreover, suppressed the thermosensitive phenotype of rpsB1, indicating the role of S1 as an extragenic suppressor of the E132K mutation. PMID:23104805

  17. Noddy, a mouse harboring a missense mutation in protocadherin-15, reveals the impact of disrupting a critical interaction site between tip-link cadherins in inner ear hair cells.

    PubMed

    Geng, Ruishuang; Sotomayor, Marcos; Kinder, Kimberly J; Gopal, Suhasini R; Gerka-Stuyt, John; Chen, Daniel H-C; Hardisty-Hughes, Rachel E; Ball, Greg; Parker, Andy; Gaudet, Rachelle; Furness, David; Brown, Steve D; Corey, David P; Alagramam, Kumar N

    2013-03-01

    In hair cells of the inner ear, sound or head movement increases tension in fine filaments termed tip links, which in turn convey force to mechanosensitive ion channels to open them. Tip links are formed by a tetramer of two cadherin proteins: protocadherin 15 (PCDH15) and cadherin 23 (CDH23), which have 11 and 27 extracellular cadherin (EC) repeats, respectively. Mutations in either protein cause inner ear disorders in mice and humans. We showed recently that these two cadherins bind tip-to-tip in a "handshake" mode that involves the EC1 and EC2 repeats of both proteins. However, a paucity of appropriate animal models has slowed our understanding both of the interaction and of how mutations of residues within the predicted interface compromise tip link integrity. Here, we present noddy, a new mouse model for hereditary deafness. Identified in a forward genetic screen, noddy homozygotes lack inner ear function. Mapping and sequencing showed that noddy mutant mice harbor an isoleucine-to-asparagine (I108N) mutation in the EC1 repeat of PCDH15. Residue I108 interacts with CDH23 EC2 in the handshake and its mutation impairs the interaction in vitro. The noddy mutation allowed us to determine the consequences of blocking the handshake in vivo: tip link formation and bundle morphology are disrupted, and mechanotransduction channels fail to remain open at rest. These results offer new insights into the interaction between PCDH15 and CDH23 and help explain the etiology of human deafness linked to mutations in the tip-link interface. PMID:23467356

  18. Missense Mutation of POU Domain Class 3 Transcription Factor 3 in Pou3f3L423P Mice Causes Reduced Nephron Number and Impaired Development of the Thick Ascending Limb of the Loop of Henle.

    PubMed

    Rieger, Alexandra; Kemter, Elisabeth; Kumar, Sudhir; Popper, Bastian; Aigner, Bernhard; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-01-01

    During nephrogenesis, POU domain class 3 transcription factor 3 (POU3F3 aka BRN1) is critically involved in development of distinct nephron segments, including the thick ascending limb of the loop of Henle (TAL). Deficiency of POU3F3 in knock-out mice leads to underdevelopment of the TAL, lack of differentiation of TAL cells, and perinatal death due to renal failure. Pou3f3L423P mutant mice, which were established in the Munich ENU Mouse Mutagenesis Project, carry a recessive point mutation in the homeobox domain of POU3F3. Homozygous Pou3f3L423P mutants are viable and fertile. The present study used functional, as well as qualitative and quantitative morphological analyses to characterize the renal phenotype of juvenile (12 days) and aged (60 weeks) homo- and heterozygous Pou3f3L423P mutant mice and age-matched wild-type controls. In both age groups, homozygous mutants vs. control mice displayed significantly smaller kidney volumes, decreased nephron numbers and mean glomerular volumes, smaller TAL volumes, as well as lower volume densities of the TAL in the kidney. No histological or ultrastructural lesions of TAL cells or glomerular cells were observed in homozygous mutant mice. Aged homozygous mutants displayed increased serum urea concentrations and reduced specific urine gravity, but no evidence of glomerular dysfunction. These results confirm the role of POU3F3 in development and function of the TAL and provide new evidence for its involvement in regulation of the nephron number in the kidney. Therefore, Pou3f3L423P mutant mice represent a valuable research model for further analyses of POU3F3 functions, or for nephrological studies examining the role of congenital low nephron numbers. PMID:27420727

  19. Missense Mutation of POU Domain Class 3 Transcription Factor 3 in Pou3f3L423P Mice Causes Reduced Nephron Number and Impaired Development of the Thick Ascending Limb of the Loop of Henle

    PubMed Central

    Rieger, Alexandra; Kemter, Elisabeth; Kumar, Sudhir; Popper, Bastian; Aigner, Bernhard; Wolf, Eckhard; Wanke, Rüdiger; Blutke, Andreas

    2016-01-01

    During nephrogenesis, POU domain class 3 transcription factor 3 (POU3F3 aka BRN1) is critically involved in development of distinct nephron segments, including the thick ascending limb of the loop of Henle (TAL). Deficiency of POU3F3 in knock-out mice leads to underdevelopment of the TAL, lack of differentiation of TAL cells, and perinatal death due to renal failure. Pou3f3L423P mutant mice, which were established in the Munich ENU Mouse Mutagenesis Project, carry a recessive point mutation in the homeobox domain of POU3F3. Homozygous Pou3f3L423P mutants are viable and fertile. The present study used functional, as well as qualitative and quantitative morphological analyses to characterize the renal phenotype of juvenile (12 days) and aged (60 weeks) homo- and heterozygous Pou3f3L423P mutant mice and age-matched wild-type controls. In both age groups, homozygous mutants vs. control mice displayed significantly smaller kidney volumes, decreased nephron numbers and mean glomerular volumes, smaller TAL volumes, as well as lower volume densities of the TAL in the kidney. No histological or ultrastructural lesions of TAL cells or glomerular cells were observed in homozygous mutant mice. Aged homozygous mutants displayed increased serum urea concentrations and reduced specific urine gravity, but no evidence of glomerular dysfunction. These results confirm the role of POU3F3 in development and function of the TAL and provide new evidence for its involvement in regulation of the nephron number in the kidney. Therefore, Pou3f3L423P mutant mice represent a valuable research model for further analyses of POU3F3 functions, or for nephrological studies examining the role of congenital low nephron numbers. PMID:27420727

  20. Missense Polymorphisms in the Adenomatous Polyposis Coli Gene and Colorectal Cancer Risk

    PubMed Central

    Cleary, Sean P.; Kim, Hyeja; Croitoru, Marina E.; Redston, Mark; Knight, Julia A.; Gallinger, Steven; Gryfe, Robert

    2009-01-01

    PURPOSE Whereas truncating germline mutations of the adenomatous polyposis coli (APC) gene give rise to familial adenomatous polyposis, missense polymorphisms of APC may confer a weaker risk for colorectal cancer. METHODS We sequenced the entire open reading frame of the APC gene and tested for two common MYH mutations in a population-based series of patients with colorectal cancer and 5 to 99 adenomas. Missense adenomatous polyposis coli alterations identified in this colorectal cancer multiple-polyp population were analyzed in a population-based series of patients with colorectal cancer and healthy control subjects. RESULTS Germline APC or mutY human homologue (MYH) alterations were identified in 16 of 39 colorectal cancer-multiple polyp patients. Four missense APC gene alterations (S130G, E1317Q, Dl822V, G2502S) were observed in 13 individuals and 3 additional patients carried presumed pathogenic (APC Y94X, biallelic MYH Y165C and heterozygous MYH G382D) mutations. When independently assessed in 971 patients with colorectal cancer and 954 healthy control subjects, none of the identified missense APC alterations conferred a significantly increased risk for colorectal cancer, odds ratio (95 percent confidence intervals): S130G=3.1 (0.29–32.25), E1317Q= 1.08 (0.59–2.74), G2502S= 1 (0.65–1.63), D1822V (heterozygous)=0.79 (0.64–0.98), D1822V (homozygous) =0.82 (0.63–1.27). CONCLUSIONS Germline missense APC alterations observed in 33 percent of patients with multiple colorectal neoplasms seemed to play a limited role in colorectal cancer risk when independently assessed by a population-based, case-control analysis. PMID:18612690

  1. Use of missense proteasome subunits for conditional lethality in the tephritid fruit flies Anastrepha suspensa and Ceratitis capitata

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Proteasomes play a critical role in eukaryote development by regulating protein degradation. In Drosophila, mis-sense mutations in the 20S proteasome subunit lead to the production of dominant temperature-sensitive (DTS) "poison subunits" or antimorphs that disrupt proteasome function. DTS5 and DTS...

  2. Thirteen new patients with guanidinoacetate methyltransferase deficiency and functional characterization of nineteen novel missense variants in the GAMT gene.

    PubMed

    Mercimek-Mahmutoglu, Saadet; Ndika, Joseph; Kanhai, Warsha; de Villemeur, Thierry Billette; Cheillan, David; Christensen, Ernst; Dorison, Nathalie; Hannig, Vickie; Hendriks, Yvonne; Hofstede, Floris C; Lion-Francois, Laurence; Lund, Allan M; Mundy, Helen; Pitelet, Gaele; Raspall-Chaure, Miquel; Scott-Schwoerer, Jessica A; Szakszon, Katalin; Valayannopoulos, Vassili; Williams, Monique; Salomons, Gajja S

    2014-04-01

    Guanidinoacetate methyltransferase deficiency (GAMT-D) is an autosomal recessively inherited disorder of creatine biosynthesis. Creatine deficiency on cranial proton magnetic resonance spectroscopy, and elevated guanidinoacetate levels in body fluids are the biomarkers of GAMT-D. In 74 patients, 50 different mutations in the GAMT gene have been identified with missense variants being the most common. Clinical and biochemical features of the patients with missense variants were obtained from their physicians using a questionnaire. In 20 patients, 17 missense variants, 25% had a severe, 55% a moderate, and 20% a mild phenotype. The effect of these variants on GAMT enzyme activity was overexpressed using primary GAMT-D fibroblasts: 17 variants retained no significant activity and are therefore considered pathogenic. Two additional variants, c.22C>A (p.Pro8Thr) and c.79T>C (p.Tyr27His) (the latter detected in control cohorts) are in fact not pathogenic as these alleles restored GAMT enzyme activity, although both were predicted to be possibly damaging by in silico analysis. We report 13 new patients with GAMT-D, six novel mutations and functional analysis of 19 missense variants, all being included in our public LOVD database. Our functional assay is important for the confirmation of the pathogenicity of identified missense variants in the GAMT gene. PMID:24415674

  3. Two male sibs with severe micrognathia and a missense variant in MED12.

    PubMed

    Prescott, Trine E; Kulseth, Mari Ann; Heimdal, Ketil R; Stadheim, Barbro; Hopp, Einar; Gambin, Tomasz; Coban Akdemir, Zeynep H; Jhangiani, Shalini N; Muzny, Donna M; Gibbs, Richard A; Lupski, James R; Stray-Pedersen, Asbjørg

    2016-08-01

    Missense variants in MED12 cause three partially overlapping dysmorphic X-linked intellectual disability (XLID) syndromes: Lujan-Fryns syndrome (also known as Lujan syndrome), FG syndrome (also known as Opitz-Kaveggia syndrome) and X-linked Ohdo syndrome. We report a family with two severely micrognathic male sibs, a 10½ year old boy and a fetus, in which hemizygosity for a previously unreported missense variant in exon 13 of MED12 (NM_005120.2), c.1862G > A, p.(Arg621Gln) was detected by whole exome sequencing. The affected sibs shared no other rare variant with relevance to the phenotype. X-chromosome inactivation in blood was completely skewed (100:0) in the unaffected heterozygous mother, most likely as a result of preferential inactivation of the X-chromosome harbouring the missense variant in MED12. Neither the unaffected brother nor the unaffected maternal grandfather carried the missense variant in MED12. In the 10½ year old boy, upper airway obstruction secondary to Pierre Robin sequence necessitated a tracheostomy for the first 10 months of life. He has mild to moderate intellectual disability and some dysmorphic features seen in MED12-related syndromes. In addition, he has a horizontal gaze paresis, anomalies of the inner ear, and a cervical block vertebra. This report contributes to the expanding phenotypic range associated with MED12-mutations. PMID:27286923

  4. Rare ATAD5 missense variants in breast and ovarian cancer patients.

    PubMed

    Maleva Kostovska, Ivana; Wang, Jing; Bogdanova, Natalia; Schürmann, Peter; Bhuju, Sabin; Geffers, Robert; Dürst, Matthias; Liebrich, Clemens; Klapdor, Rüdiger; Christiansen, Hans; Park-Simon, Tjoung-Won; Hillemanns, Peter; Plaseska-Karanfilska, Dijana; Dörk, Thilo

    2016-06-28

    ATAD5/ELG1 is a protein crucially involved in replication and maintenance of genome stability. ATAD5 has recently been identified as a genomic risk locus for both breast and ovarian cancer through genome-wide association studies. We aimed to investigate the spectrum of coding ATAD5 germ-line mutations in hospital-based series of patients with triple-negative breast cancer or serous ovarian cancer compared with healthy controls. The ATAD5 coding and adjacent splice site regions were analyzed by targeted next-generation sequencing of DNA samples from 273 cancer patients, including 114 patients with triple-negative breast cancer and 159 patients with serous epithelial ovarian cancer, and from 276 healthy females. Among 42 different variants identified, twenty-two were rare missense substitutions, of which 14 were classified as pathogenic by at least one in silico prediction tool. Three of four novel missense substitutions (p.S354I, p.H974R and p.K1466N) were predicted to be pathogenic and were all identified in ovarian cancer patients. Overall, rare missense variants with predicted pathogenicity tended to be enriched in ovarian cancer patients (14/159) versus controls (11/276) (p = 0.05, 2df). While truncating germ-line variants in ATAD5 were not detected, it remains possible that several rare missense variants contribute to genetic susceptibility toward epithelial ovarian carcinomas. PMID:27045477

  5. Missense Variants in ATM in 26,101 Breast Cancer Cases and 29,842 Controls

    PubMed Central

    Fletcher, Olivia; Johnson, Nichola; dos Santos Silva, Isabel; Orr, Nick; Ashworth, Alan; Nevanlinna, Heli; Heikkinen, Tuomas; Aittomäki, Kristiina; Blomqvist, Carl; Burwinkel, Barbara; Bartram, Claus R.; Meindl, Alfons; Schmutzler, Rita K.; Cox, Angela; Brock, Ian; Elliott, Graeme; Reed, Malcolm W. R.; Southey, Melissa C.; Smith, Letitia; Spurdle, Amanda B.; Hopper, John L.; Couch, Fergus J.; Olson, Janet E.; Wang, Xianshu; Fredericksen, Zachary; Schürmann, Peter; Waltes, Regina; Bremer, Michael; Dörk, Thilo; Devilee, Peter; van Asperen, Christie J.; Tollenaar, Rob A.E.M.; Seynaeve, Caroline; Hall, Per; Czene, Kamila; Humphreys, Keith; Liu, Jianjun; Ahmed, Shahana; Dunning, Alison M.; Maranian, Melanie; Pharoah, Paul D.P.; Chenevix-Trench, Georgia; Beesley, Jonathan; Investigators, kConFab; Group, AOCS; Bogdanova, Natalia V.; Antonenkova, Natalia N.; Zalutsky, Iosif V.; Anton-Culver, Hoda; Ziogas, Argyrios; Brauch, Hiltrud; Ko, Yon-Dschun; Hamann, Ute; Fasching, Peter A.; Strick, Reiner; Ekici, Arif B.; Beckmann, Matthias W.; Giles, Graham G.; Severi, Gianluca; Baglietto, Laura; English, Dallas R.; Milne, Roger L.; Benítez, Javier; Arias, José Ignacio; Pita, Guillermo; Nordestgaard, Børge G.; Bojesen, Stig E.; Flyger, Henrik; Kang, Daehee; Yoo, Keun-Young; Noh, Dong Young; Mannermaa, Arto; Kataja, Vesa; Kosma, Veli-Matti; García-Closas, Montserrat; Chanock, Stephen; Lissowska, Jolanta; Brinton, Louise A.; Chang-Claude, Jenny; Wang- Gohrke, Shan; Broeks, Annegien; Schmidt, Marjanka K; van Leeuwen, Flora E; Van ‘t Veer, Laura J; Margolin, Sara; Lindblom, Annika; Humphreys, Manjeet K.; Morrison, Jonathan; Platte, Radka; Easton, Douglas F.; Peto, Julian

    2010-01-01

    Background Truncating mutations in ATM have been shown to increase the risk of breast cancer but the effect of missense variants remains contentious. Methods We have genotyped five polymorphic (MAF 0.9% to 2.6%) missense single nucleotide polymorphisms (SNPs) in ATM (S49C, S707P, F858L, P1054R, L1420F) in 26,101 breast cancer cases and 29,842 controls from 23 studies in the Breast Cancer Association Consortium (BCAC). Results Combining data from all five SNPs, the OR was 1.05 for being a heterozygote for any of the SNPs and 1.51 for being a rare homozygote for any of the SNPs with an overall trend OR=1.06 (Ptrend=0.04). The trend OR among bilateral and familial cases was 1.12 (95% CI 1.02-1.23; Ptrend=0.02). Conclusions In this large combined analysis, these 5 missense ATM SNPs were associated with a small increased risk of breast cancer, explaining an estimated 0.03% of the excess familial risk of breast cancer. Impact Testing the combined effects of rare missense variants in known breast cancer genes in large collaborative studies should clarify their overall contribution to breast cancer susceptibility. PMID:20826828

  6. Classification of Missense Substitutions in the BRCA Genes: a Database Dedicated to Ex-UVs

    PubMed Central

    Vallée, Maxime P.; Francy, Tiana C.; Judkins, Megan K.; Babikyan, Davit; Lesueur, Fabienne; Gammon, Amanda; Goldgar, David E.; Couch, Fergus J.; Tavtigian, Sean V.

    2012-01-01

    Unclassified sequence variants (UV) arising from clinical mutation screening of cancer susceptibility genes present a frustrating issue to clinical genetics services and the patients that they serve. We created an open-access database holding missense substitutions from the breast and ovarian cancer susceptibility genes BRCA1 and BRCA2. The main inclusion criterion is that each variant should have been assessed in a published work that used the Bayesian integrated evaluation of unclassified BRCA gene variants. Transfer of data on these substitutions from the original publications to our database afforded an opportunity to analyze the missense substitutions under a single model and to remove inconsistencies that arose during the evolution of the integrated evaluation over the last decade. This analysis also afforded the opportunity to re-classify these missense substitutions according to the recently published IARC 5-Class system. From an initial set of 248 missense substitutions, 31 were set aside due to non-negligible probability to interfere with splicing. Of the remaining substitutions, 28 fell into one of the two pathogenic classes (IARC Classes 4 or 5), 174 fell into one of the two non-pathogenic classes (IARC Classes 1 or 2), and 15 remain in IARC Class 3, “Uncertain”. The database is available at . PMID:21990165

  7. High incidence of functional ion-channel abnormalities in a consecutive Long QT cohort with novel missense genetic variants of unknown significance

    PubMed Central

    Steffensen, Annette Buur; Refaat, Marwan M.; David, Jens-Peter; Mujezinovic, Amer; Calloe, Kirstine; Wojciak, Julianne; Nussbaum, Robert L.; Scheinman, Melvin M.; Schmitt, Nicole

    2015-01-01

    The Long QT syndrome (LQTS) is a disorder characterized by a prolongation of the QT interval and a propensity to ventricular tachyarrhythmias, which may lead to syncope, cardiac arrest, or sudden death. Our objective was to (1) determine the incidence of variants with unknown significance (VUS) in a cohort of consecutive LQTS patients and (2) to determine the percentage of those with novel missense VUS that have demonstrable functional channel abnormalities from a single referral center. We performed genetic screening of candidate genes in 39 probands with a diagnosis of LQTS to identify mutations and variants. Seven variants of unknown significance were identified, six were missense variants and one was a splice site variant. We investigated the six novel missense VUS in five patients; three missense variants in KCNQ1 (L236R, W379R, Y522S) and three missense variants in KCNH2 (R35W, S620G, V491I). We employed two-electrode voltage-clamp experiments in Xenopus laevis oocytes and confocal imaging to characterize the novel missense mutations functionally. We revealed electrophysiological and trafficking loss-of-function phenotypes. This report emphasizes the frequency of adverse channel function in patients with LQTS and the importance of heterologous studies to define channel function. PMID:26066609

  8. Multigene testing of moderate-risk genes: be mindful of the missense

    PubMed Central

    Young, E L; Feng, B J; Stark, A W; Damiola, F; Durand, G; Forey, N; Francy, T C; Gammon, A; Kohlmann, W K; Kaphingst, K A; McKay-Chopin, S; Nguyen-Dumont, T; Oliver, J; Paquette, A M; Pertesi, M; Robinot, N; Rosenthal, J S; Vallee, M; Voegele, C; Hopper, J L; Southey, M C; Andrulis, I L; John, E M; Hashibe, M; Gertz, J; Le Calvez-Kelm, F; Lesueur, F; Goldgar, D E; Tavtigian, S V

    2016-01-01

    Background Moderate-risk genes have not been extensively studied, and missense substitutions in them are generally returned to patients as variants of uncertain significance lacking clearly defined risk estimates. The fraction of early-onset breast cancer cases carrying moderate-risk genotypes and quantitative methods for flagging variants for further analysis have not been established. Methods We evaluated rare missense substitutions identified from a mutation screen of ATM, CHEK2, MRE11A, RAD50, NBN, RAD51, RINT1, XRCC2 and BARD1 in 1297 cases of early-onset breast cancer and 1121 controls via scores from Align-Grantham Variation Grantham Deviation (GVGD), combined annotation dependent depletion (CADD), multivariate analysis of protein polymorphism (MAPP) and PolyPhen-2. We also evaluated subjects by polygenotype from 18 breast cancer risk SNPs. From these analyses, we estimated the fraction of cases and controls that reach a breast cancer OR≥2.5 threshold. Results Analysis of mutation screening data from the nine genes revealed that 7.5% of cases and 2.4% of controls were carriers of at least one rare variant with an average OR≥2.5. 2.1% of cases and 1.2% of controls had a polygenotype with an average OR≥2.5. Conclusions Among early-onset breast cancer cases, 9.6% had a genotype associated with an increased risk sufficient to affect clinical management recommendations. Over two-thirds of variants conferring this level of risk were rare missense substitutions in moderate-risk genes. Placement in the estimated OR≥2.5 group by at least two of these missense analysis programs should be used to prioritise variants for further study. Panel testing often creates more heat than light; quantitative approaches to variant prioritisation and classification may facilitate more efficient clinical classification of variants. PMID:26787654

  9. Integrating population variation and protein structural analysis to improve clinical interpretation of missense variation: application to the WD40 domain.

    PubMed

    Laskowski, Roman A; Tyagi, Nidhi; Johnson, Diana; Joss, Shelagh; Kinning, Esther; McWilliam, Catherine; Splitt, Miranda; Thornton, Janet M; Firth, Helen V; Wright, Caroline F

    2016-03-01

    We present a generic, multidisciplinary approach for improving our understanding of novel missense variants in recently discovered disease genes exhibiting genetic heterogeneity, by combining clinical and population genetics with protein structural analysis. Using six new de novo missense diagnoses in TBL1XR1 from the Deciphering Developmental Disorders study, together with population variation data, we show that the β-propeller structure of the ubiquitous WD40 domain provides a convincing way to discriminate between pathogenic and benign variation. Children with likely pathogenic mutations in this gene have severely delayed language development, often accompanied by intellectual disability, autism, dysmorphology and gastrointestinal problems. Amino acids affected by likely pathogenic missense mutations are either crucial for the stability of the fold, forming part of a highly conserved symmetrically repeating hydrogen-bonded tetrad, or located at the top face of the β-propeller, where 'hotspot' residues affect the binding of β-catenin to the TBLR1 protein. In contrast, those altered by population variation are significantly less likely to be spatially clustered towards the top face or to be at buried or highly conserved residues. This result is useful not only for interpreting benign and pathogenic missense variants in this gene, but also in other WD40 domains, many of which are associated with disease. PMID:26740553

  10. Seventeen novel mutations that cause profound biotinidase deficiency.

    PubMed

    Wolf, B; Jensen, K; Hüner, G; Demirkol, M; Baykal, T; Divry, P; Rolland, M-O; Perez-Cerdá, C; Ugarte, M; Straussberg, R; Basel-Vanagaite, L; Baumgartner, E R; Suormala, T; Scholl, S; Das, A M; Schweitzer, S; Pronicka, E; Sykut-Cegielska, J

    2002-01-01

    We report 17 novel mutations that cause profound biotinidase deficiency. Six of the mutations are due to deletions, whereas the remaining 11 mutations are missense mutations located throughout the gene and encode amino acids that are conserved in mammals. Our results increase the total number of different mutations that cause biotinidase deficiency to 79. These additional mutations will undoubtedly be helpful in identifying structure/function relationships once the three-dimensional structure of biotinidase is determined. PMID:12359137

  11. Molecular modeling indicates distinct classes of missense variants with mild and severe XLRS phenotypes

    PubMed Central

    Sergeev, Yuri V.; Vitale, Susan; Sieving, Paul A.; Vincent, Ajoy; Robson, Anthony G.; Moore, Anthony T.; Webster, Andrew R.; Holder, Graham E.

    2013-01-01

    X-linked retinoschisis (XLRS) is a vitreo-retinal degeneration caused by mutations in the RS1 gene which encodes the protein retinoschisin (RS1), required for the structural and functional integrity of the retina. Data are presented from a group of 38 XLRS patients from Moorfields Eye Hospital (London, UK) who had one of 18 missense mutations in RS1. Patients were grouped based on mutation severity predicted by molecular modeling: mild (class I), moderate (intermediate) and severe (class II). Most patients had an electronegative scotopic bright flash electroretinogram  (ERG) (reduced b/a-wave ratio) in keeping with predominant inner retinal dysfunction. An association between the type of structural RS1 alterations and the severity of b/a-wave reduction was found in all but the oldest group of patients, significant in patients aged 15–30 years. Severe RS1 missense changes were associated with a lower ERG b/a ratio than were mild changes, suggesting that the extent of inner retinal dysfunction is influenced by the effect of the mutations on protein structure. The majority of class I mutations showed no changes involving cysteine residues. Class II mutations caused severe perturbations due to the removal or insertion of cysteine residues or due to changes in the hydrophobic core. The ERG b/a ratio in intermediate cases was abnormal but showed significant variability, possibly related to the role of proline or arginine residues. We also conducted a second study, using a completely independent cohort, to indicate a genotype–ERG phenotype correlation. PMID:23847049

  12. Most of rare missense alleles in humans are deleterious:implications for evolution of complex disease and associationstudies

    SciTech Connect

    Kryukov, Gregory V.; Pennacchio, Len A.; Sunyaev, Shamil R.

    2006-10-24

    The accumulation of mildly deleterious missense mutations inindividual human genomes has been proposed to be a genetic basis forcomplex diseases. The plausibility of this hypothesis depends onquantitative estimates of the prevalence of mildly deleterious de novomutations and polymorphic variants in humans and on the intensity ofselective pressure against them. We combined analysis of mutationscausing human Mendelian diseases, human-chimpanzee divergence andsystematic data on human SNPs and found that about 20 percent of newmissense mutations in humans result in a loss of function, while about 27percent are effectively neutral. Thus, more than half of new missensemutations have mildly deleterious effects. These mutations give rise tomany low frequency deleterious allelic variants in the human populationas evident from a new dataset of 37 genes sequenced in over 1,500individual human chromosomes. Surprisingly, up to 70 percent of lowfrequency missense alleles are mildly deleterious and associated with aheterozygous fitness loss in the range 0.001-0.003. Thus, the low allelefrequency of an amino acid variant can by itself serve as a predictor ofits functional significance. Several recent studies have reported asignificant excess of rare missense variants in disease populationscompared to controls in candidate genes or pathways. These studies wouldbe unlikely to work if most rare variants were neutral or if rarevariants were not a significant contributor to the genetic component ofphenotypic inheritance. Our results provide a justification for thesetypes of candidate gene (pathway) association studies and imply thatmutation-selection balance may be a feasible mechanism for evolution ofsome common diseases.

  13. Carrier frequency of guanidinoacetate methyltransferase deficiency in the general population by functional characterization of missense variants in the GAMT gene.

    PubMed

    Desroches, Caro-Lyne; Patel, Jaina; Wang, Peixiang; Minassian, Berge; Marshall, Christian R; Salomons, Gajja S; Mercimek-Mahmutoglu, Saadet

    2015-12-01

    Guanidinoacetate methyltransferase (GAMT) deficiency is a neurodegenerative disease. Although no symptomatic patients on treatment achieved normal neurodevelopment, three asymptomatic newborns were reported with normal neurodevelopmental outcome on neonatal treatment. GAMT deficiency is therefore a candidate for newborn screening programs, but there are no studies for the carrier frequency of this disease in the general population. To determine carrier frequency of GAMT deficiency, we studied the variants in the GAMT gene reported in the Exome Variant Server database and performed functional characterization of missense variants. We used previously cloned GAMT transcript variant 1 (7 missense variants) and cloned a novel GAMT transcript variant 2 (5 missense variants). The latter was used in Exome Variant Server database according to recommendations of the Human Genome Variation Society. There were 4 missense variants (1 previously reported and 3 novel) with low GAMT enzyme activity indicating pathogenicity. Additionally, there was one novel frameshift and one novel nonsense variant likely pathogenic. There was no measurable GAMT enzyme activity in the wild type of GAMT transcript variant 2. We concluded that GAMT transcript variant 2 is not involved in GAMT protein synthesis. For this reason, Human Genome Variation Society should use mutation nomenclature according to the coding region of the GAMT transcript variant 1. The carrier frequency of GAMT deficiency was 0.123 % in the general population. As early diagnosis results in normal neurodevelopmental outcome, GAMT deficiency should be included in newborn screening programs to diagnose individuals at the asymptomatic stage of the disease to prevent permanent neurodevelopmental disability. PMID:26003046

  14. Understanding N-Acetyl-L-Glutamate Synthase Deficiency: Mutational Spectrum, Impact of Clinical Mutations on Enzyme Functionality, and Structural Considerations.

    PubMed

    Sancho-Vaello, Enea; Marco-Marín, Clara; Gougeard, Nadine; Fernández-Murga, Leonor; Rüfenacht, Véronique; Mustedanagic, Merima; Rubio, Vicente; Häberle, Johannes

    2016-07-01

    N-acetyl-L-glutamate synthase (NAGS) deficiency (NAGSD), the rarest urea cycle defect, is clinically indistinguishable from carbamoyl phosphate synthetase 1 deficiency, rendering the identification of NAGS gene mutations key for differentiation, which is crucial, as only NAGSD has substitutive therapy. Over the last 13 years, we have identified 43 patients from 33 families with NAGS mutations, of which 14 were novel. Overall, 36 NAGS mutations have been found so far in 56 patients from 42 families, of which 76% are homozygous for the mutant allele. 61% of mutations are missense changes. Lack or decrease of NAGS protein is predicted for ∼1/3 of mutations. Missense mutations frequency is inhomogeneous along NAGS: null for exon 1, but six in exon 6, which reflects the paramount substrate binding/catalytic role of the C-terminal domain (GNAT domain). Correspondingly, phenotypes associated with missense mutations mapping in the GNAT domain are more severe than phenotypes of amino acid kinase domain-mapping missense mutations. Enzyme activity and stability assays with 12 mutations introduced into pure recombinant Pseudomonas aeruginosa NAGS, together with in silico structural analysis, support the pathogenic role of most NAGSD-associated mutations found. The disease-causing mechanisms appear to be, from higher to lower frequency, decreased solubility/stability, aberrant kinetics/catalysis, and altered arginine modulation. PMID:27037498

  15. Alternating Hemiplegia of Childhood-Related Neural and Behavioural Phenotypes in Na+,K+-ATPase α3 Missense Mutant Mice

    PubMed Central

    Kirshenbaum, Greer S.; Dawson, Neil; Mullins, Jonathan G. L.; Johnston, Tom H.; Drinkhill, Mark J.; Edwards, Ian J.; Fox, Susan H.; Pratt, Judith A.; Brotchie, Jonathan M.; Roder, John C.; Clapcote, Steven J.

    2013-01-01

    Missense mutations in ATP1A3 encoding Na+,K+-ATPase α3 have been identified as the primary cause of alternating hemiplegia of childhood (AHC), a motor disorder with onset typically before the age of 6 months. Affected children tend to be of short stature and can also have epilepsy, ataxia and learning disability. The Na+,K+-ATPase has a well-known role in maintaining electrochemical gradients across cell membranes, but our understanding of how the mutations cause AHC is limited. Myshkin mutant mice carry an amino acid change (I810N) that affects the same position in Na+,K+-ATPase α3 as I810S found in AHC. Using molecular modelling, we show that the Myshkin and AHC mutations display similarly severe structural impacts on Na+,K+-ATPase α3, including upon the K+ pore and predicted K+ binding sites. Behavioural analysis of Myshkin mice revealed phenotypic abnormalities similar to symptoms of AHC, including motor dysfunction and cognitive impairment. 2-DG imaging of Myshkin mice identified compromised thalamocortical functioning that includes a deficit in frontal cortex functioning (hypofrontality), directly mirroring that reported in AHC, along with reduced thalamocortical functional connectivity. Our results thus provide validation for missense mutations in Na+,K+-ATPase α3 as a cause of AHC, and highlight Myshkin mice as a starting point for the exploration of disease mechanisms and novel treatments in AHC. PMID:23527305

  16. Compound EGFR mutation is frequently detected with co-mutations of actionable genes and associated with poor clinical outcome in lung adenocarcinoma

    PubMed Central

    Kim, Eun Young; Cho, Eun Na; Park, Heae Surng; Hong, Ji Young; Lim, Seri; Youn, Jong Pil; Hwang, Seung Yong; Chang, Yoon Soo

    2016-01-01

    Compound EGFR mutations, defined as double or multiple mutations in the EGFR tyrosine kinase domain, are frequently detected with advances in sequencing technology but its clinical significance is unclear. This study analyzed 61 cases of EGFR mutation positive lung adenocarcinoma using next-generation sequencing (NGS) based repeated deep sequencing panel of 16 genes that contain actionable mutations and investigated clinical implication of compound EGFR mutations. Compound EGFR mutation was detected in 15 (24.6%) of 61 cases of EGFR mutation-positive lung adenocarcinoma. The majority (12/15) of compound mutations are combination of the atypical mutation and typical mutations such as exon19 deletion, L858R or G719X substitutions, or exon 20 insertion whereas 3 were combinations of rare atypical mutations. The patients with compound mutation showed shorter overall survival than those with simple mutations (83.7 vs. 72.8 mo; P = 0.020, Breslow test). Among the 115 missense mutations discovered in the tested genes, a few number of actionable mutations were detected irrelevant to the subtype of EGFR mutations, including ALK rearrangement, BCL2L11 intron 2 deletion, KRAS c.35G>A, PIK3CA c.1633G>A which are possible target of crizotinib, BH3 mimetics, MEK inhibitors, and PI3K-tyrosine kinase inhibitors, respectively. 31 missense mutations were detected in the cases with simple mutations whereas 84 in those with compound mutation, showing that the cases with compound missense mutation have higher burden of missense mutations (P = 0.001, independent sample t-test). Compound EGFR mutations are detected at a high frequency using NGS-based repeated deep sequencing. Because patients with compound EGFR mutations showed poor clinical outcomes, they should be closely monitored during follow-up. PMID:26785607

  17. Atypical phenotype in two patients with LAMA2 mutations.

    PubMed

    Marques, Joana; Duarte, Sofia T; Costa, Sónia; Jacinto, Sandra; Oliveira, Jorge; Oliveira, Márcia E; Santos, Rosário; Bronze-da-Rocha, Elsa; Silvestre, Ana Rita; Calado, Eulália; Evangelista, Teresinha

    2014-05-01

    Congenital muscular dystrophy type 1A is caused by mutations in the LAMA2 gene, which encodes the α2-chain of laminin. We report two patients with partial laminin-α2 deficiency and atypical phenotypes, one with almost exclusive central nervous system involvement (cognitive impairment and refractory epilepsy) and the second with marked cardiac dysfunction, rigid spine syndrome and limb-girdle weakness. Patients underwent clinical, histopathological, imaging and genetic studies. Both cases have two heterozygous LAMA2 variants sharing a potentially pathogenic missense mutation c.2461A>C (p.Thr821Pro) located in exon 18. Brain MRI was instrumental for the diagnosis, since muscular examination and motor achievements were normal in the first patient and there was a severe cardiac involvement in the second. The clinical phenotype of the patients is markedly different which could in part be explained by the different combination of mutations types (two missense versus a missense and a truncating mutation). PMID:24534542

  18. Functional analysis of missense variants in the TRESK (KCNK18) K channel.

    PubMed

    Andres-Enguix, Isabelle; Shang, Lijun; Stansfeld, Phillip J; Morahan, Julia M; Sansom, Mark S P; Lafrenière, Ronald G; Roy, Bishakha; Griffiths, Lyn R; Rouleau, Guy A; Ebers, George C; Cader, Zameel M; Tucker, Stephen J

    2012-01-01

    A loss of function mutation in the TRESK K2P potassium channel (KCNK18), has recently been linked with typical familial migraine with aura. We now report the functional characterisation of additional TRESK channel missense variants identified in unrelated patients. Several variants either had no apparent functional effect, or they caused a reduction in channel activity. However, the C110R variant was found to cause a complete loss of TRESK function, yet is present in both sporadic migraine and control cohorts, and no variation in KCNK18 copy number was found. Thus despite the previously identified association between loss of TRESK channel activity and migraine in a large multigenerational pedigree, this finding indicates that a single non-functional TRESK variant is not alone sufficient to cause typical migraine and highlights the genetic complexity of this disorder. PMID:22355750

  19. Compromised Catalysis and Potential Folding Defects in in Vitro Studies of Missense Mutants Associated with Hereditary Phosphoglucomutase 1 Deficiency*

    PubMed Central

    Lee, Yingying; Stiers, Kyle M.; Kain, Bailee N.; Beamer, Lesa J.

    2014-01-01

    Recent studies have identified phosphoglucomutase 1 (PGM1) deficiency as an inherited metabolic disorder in humans. Affected patients show multiple disease phenotypes, including dilated cardiomyopathy, exercise intolerance, and hepatopathy, reflecting the central role of the enzyme in glucose metabolism. We present here the first in vitro biochemical characterization of 13 missense mutations involved in PGM1 deficiency. The biochemical phenotypes of the PGM1 mutants cluster into two groups: those with compromised catalysis and those with possible folding defects. Relative to the recombinant wild-type enzyme, certain missense mutants show greatly decreased expression of soluble protein and/or increased aggregation. In contrast, other missense variants are well behaved in solution, but show dramatic reductions in enzyme activity, with kcat/Km often <1.5% of wild-type. Modest changes in protein conformation and flexibility are also apparent in some of the catalytically impaired variants. In the case of the G291R mutant, severely compromised activity is linked to the inability of a key active site serine to be phosphorylated, a prerequisite for catalysis. Our results complement previous in vivo studies, which suggest that both protein misfolding and catalytic impairment may play a role in PGM1 deficiency. PMID:25288802

  20. Proteasome machinery is instrumental in a common gain-of-function program of the p53 missense mutants in cancer.

    PubMed

    Walerych, Dawid; Lisek, Kamil; Sommaggio, Roberta; Piazza, Silvano; Ciani, Yari; Dalla, Emiliano; Rajkowska, Katarzyna; Gaweda-Walerych, Katarzyna; Ingallina, Eleonora; Tonelli, Claudia; Morelli, Marco J; Amato, Angela; Eterno, Vincenzo; Zambelli, Alberto; Rosato, Antonio; Amati, Bruno; Wiśniewski, Jacek R; Del Sal, Giannino

    2016-08-01

    In cancer, the tumour suppressor gene TP53 undergoes frequent missense mutations that endow mutant p53 proteins with oncogenic properties. Until now, a universal mutant p53 gain-of-function program has not been defined. By means of multi-omics: proteome, DNA interactome (chromatin immunoprecipitation followed by sequencing) and transcriptome (RNA sequencing/microarray) analyses, we identified the proteasome machinery as a common target of p53 missense mutants. The mutant p53-proteasome axis globally affects protein homeostasis, inhibiting multiple tumour-suppressive pathways, including the anti-oncogenic KSRP-microRNA pathway. In cancer cells, p53 missense mutants cooperate with Nrf2 (NFE2L2) to activate proteasome gene transcription, resulting in resistance to the proteasome inhibitor carfilzomib. Combining the mutant p53-inactivating agent APR-246 (PRIMA-1MET) with the proteasome inhibitor carfilzomib is effective in overcoming chemoresistance in triple-negative breast cancer cells, creating a therapeutic opportunity for treatment of solid tumours and metastasis with mutant p53. PMID:27347849

  1. A frequent tyrosinase gene mutation associated with type I-A (tyroinase-negative) oculocutaneous albinism in Puerto Rico

    SciTech Connect

    Oetting, W.S.; Witkop, C.J. Jr.; Brown, S.A.; Fryer, J.P.; Bloom, K.E.; King, R.A. ); Colomer, R. )

    1993-01-01

    The authors have determined the mutations in the tyrosinase gene from 12 unrelated Puerto Rican individuals who have type I-A (tyrosinase-negative) oculocutaneous albinism (OCA). All but one individual are of Hispanic descent. Nine individuals were homozygous for a missense mutation (G47D) in exon I at codon 47. Two individuals were heterozygous for the G47D mutation, with one having a missense mutation at codon 373 (T373K) in the homologous allele and the other having an undetermined mutation in the homologous allele. One individual with negroid features was homozygous for a nonsense mutation (W236X). The population migration between Puerto Rico and the Canary Islands is well recognized. Analysis of three individuals with OCA from the Canary Islands showed that one was a compound heterozygote for the G47D mutation and for a novel missense mutation (L216M), one was homozygous for a missense mutation (P81L), and one was heterozygous for the missense mutation P81L. The G47D and P81L missense mutations have been previously described in extended families in the United States. Haplotypes were determined using four polymorphisms linked to the tyrosinase locus. Haplotype analysis showed that the G47D mutation occurred on a single haplotype, consistent with a common founder for all individuals having this mutation. Two different haplotypes were found associated with the P81L mutation, suggesting that this may be either a recurring mutation for the tyrosinase gene or a recombination between haplotypes. 28 refs., 1 fig., 3 tabs.

  2. Glucocerebrosidase mutations in Gaucher disease.

    PubMed Central

    Beutler, E.; Demina, A.; Gelbart, T.

    1994-01-01

    BACKGROUND: Thirty-six mutations that cause Gaucher disease, the most common glycolipid storage disorder, are known. Although both alleles of most patients with the disease contain one of these mutations, in a few patients one or both disease-producing alleles have remained unidentified. Identification of mutations in these patients is useful for genetic counseling. MATERIALS AND METHODS: The DNA from 23 Gaucher disease patients in whom at least one glucocerebrosidase allele did not contain any of the 36 previously described mutations has been examined by single strand conformation polymorphism (SSCP) analysis, followed by sequencing of regions in which abnormalities were detected. RESULTS: Eight previously undescribed mutations were detected. In exon 3, a deletion of a cytosine at cDNA nt 203 was found. In exon 6, three missense mutations were identified: a C-->A transversion at cDNA nt 644 (Ala176-->Asp), a C-->A transversion at cDNA nt 661 that resulted in a (Pro182-->Thr), and a G-->A transition at cDNA nt 721 (Gly202-->Arg). Two missense mutations were found in exon 7: a G-->A transition at cDNA nt 887 (Arg257-->Gln) and a C-->T at cDNA nt 970 (Arg285-->Cys). Two missense mutations were found in exon 9: a T-->G at cDNA nt 1249 (Trp378-->Gly) and a G-->A at cDNA nt 1255 (Asp380-->Asn). In addition to these disease-producing mutations, a silent C-->G transversion at cDNA nt 1431, occurring in a gene that already contained the 1226G mutation, was found in one family. CONCLUSIONS: The mutations described here and previously known can be classified as mild, severe, or lethal, on the basis of their effect on enzyme production and on clinical phenotype, and as polymorphic or sporadic, on the basis of the haplotype in which they are found. Rare mutations such as the new ones described here are sporadic in nature. PMID:8790604

  3. A Novel Mutation of DAX-1 Associated with Secretory Azoospermia

    PubMed Central

    Yang, Lihua; Liu, Yuchen; Diao, Ruiying; Cai, Zhiming; Li, Honggang; Gui, Yaoting

    2015-01-01

    Secretory azoospermia is a severe form of male infertility caused by unknown factors. DAX-1 is predominantly expressed in mammalian reproductive tissues and plays an important role in spermatogenesis because Dax-1 knockout male mice show spermatogenesis defects. To examine whether DAX-1 is involved in the pathogenesis of secretory azoospermia in humans, we sequenced all of the exons of DAX-1 in 776 patients diagnosed with secretory azoospermia and 709 proven fertile men. A number of coding mutations unique to the patient group, including two synonymous mutations and six missense mutations, were identified. Of the missense mutations, our functional assay demonstrated that the V385L mutation caused the reduced functioning of DAX-1. This novel mutation (p. V385L) of DAX-1 is the first to be identified in association with secretory azoospermia, thereby highlighting the important role of DAX-1 in spermatogenesis. PMID:26207377

  4. Four novel mutations of the coproporphyrinogen III oxidase gene.

    PubMed

    Aurizi, C; Lupia Palmieri, G; Barbieri, L; Macrì, A; Sorge, F; Usai, G; Biolcati, G

    2009-01-01

    Here we report the characterization of four novel mutations and a previously described one of the coproporphyrinogen III oxidase (CPO) gene in five Italian patients affected by Hereditary Coproporphyria (HCP). Three of the novel genetic variants are missense mutations (p.Gly242Cys; p.Leu398Pro; p.Ser245Phe) and one is a frameshift mutation (p.Gly188TrpfsX45). PMID:19267996

  5. Investigation of Endoglin Wild-Type and Missense Mutant Protein Heterodimerisation Using Fluorescence Microscopy Based IF, BiFC and FRET Analyses

    PubMed Central

    Förg, Tassilo; Hafner, Mathias; Lux, Andreas

    2014-01-01

    The homodimeric transmembrane receptor endoglin (CD105) plays an important role in angiogenesis. This is highlighted by mutations in its gene, causing the vascular disorder HHT1. The main role of endoglin function has been assigned to the modulation of transforming growth factor β and bone morphogenetic protein signalling in endothelial cells. Nevertheless, other functions of endoglin have been revealed to be involved in different cellular functions and in other cell types than endothelial cells. Compared to the exploration of its natural function, little experimental data have been gathered about the mode of action of endoglin HHT mutations at the cellular level, especially missense mutations, and to what degree these might interfere with normal endoglin function. In this paper, we have used fluorescence-based microscopic techniques, such as bimolecular fluorescence complementation (BiFC), immunofluorescence staining with the endoglin specific monoclonal antibody SN6, and protein interaction studies by Förster Resonance Energy Transfer (FRET) to investigate the formation and cellular localisation of possible homo- and heterodimers composed of endoglin wild-type and endoglin missense mutant proteins. The results show that all of the investigated missense mutants dimerise with themselves, as well as with wild-type endoglin, and localise, depending on the position of the affected amino acid, either in the rough endoplasmic reticulum (rER) or in the plasma membrane of the cells. We show that the rER retained mutants reduce the amount of endogenous wild-type endoglin on the plasma membrane through interception in the rER when transiently or stably expressed in HMEC-1 endothelial cells. As a result of this, endoglin modulated TGF-β1 signal transduction is also abrogated, which is not due to TGF-β receptor ER trafficking interference. Protein interaction analyses by FRET show that rER located endoglin missense mutants do not perturb protein processing of other

  6. Diverse mutations in patients with Menkes disease often lead to exon skipping

    SciTech Connect

    Das, S.; Levinson, Levinson, B.; Whitney, S.; Vulpe, C.; Packman, S.; Gitschier, J.

    1994-11-01

    Fibroblast cultures from 12 unrelated patients with classical Menkes disease were analyzed for mutations in the MNK gene, by reverse transcription-PCR (RT-PCR) and chemical cleavage mismatch detection. Mutations were observed in 10 patients, and in each case a different mutation was present. All of the mutations would be predicted to have adverse effects on protein expression. Mutations that resulted in splicing abnormalities, detected by RT-PCR alone, were observed in six patients and included two splice-site changes, a nonsense mutation, a missense mutation, a small duplication, and a small deletion. Chemical cleavage analysis of the remaining six patients revealed the presence of one missense mutation. A valine/leucine polymorphism was also observed. These findings, combined with the prior observation of deletions in 15%-20% of Menkes patients, suggest that Southern blot hybridization and RT-PCR will identify mutations in the majority of patients. 26 refs., 3 figs., 2 tabs.

  7. Phenotypic expression in von Hippel-Lindau disease: correlations with germline VHL gene mutations.

    PubMed Central

    Maher, E R; Webster, A R; Richards, F M; Green, J S; Crossey, P A; Payne, S J; Moore, A T

    1996-01-01

    Von Hippel-Lindau disease is an autosomal dominantly inherited familial cancer syndrome predisposing to retinal and central nervous system haemangioblastomas, renal cell carcinoma, and phaeochromocytoma. VHL disease shows variable expression and interfamilial differences in predisposition to phaeochromocytoma. In a previous study of 65 VHL kindreds with defined VHL mutations we detected significant differences between VHL families with and without phaeochromocytoma such that missense mutations were more common and large deletions or protein truncating mutations less frequent in phaeochromocytoma positive families. To investigate the significance and cause of this association further, we studied 138 VHL kindreds for germline mutations and calculated the age related tumour risks for different classes of VHL gene mutations. Using SSCP, heteroduplex and Southern analysis we identified a germline VHL gene mutation in 101 families (73%). Direct sequencing of the VHL coding region further increased the mutation detection rate to 81%. In addition to precise presymptomatic diagnosis, identification of a VHL gene mutation can provide an indication of the likely phenotype. We found that large deletions and mutations predicted to cause a truncated protein were associated with a lower risk of phaeochromocytoma (6% and 9% at 30 and 50 years, respectively) than missense mutations (40% and 59%, respectively) and that missense mutations at codon 167 were associated with a high risk of phaeochromocytoma (53% and 82% at ages 30 and 50 years). Cumulative probabilities of renal cell carcinoma did not differ between the two groups (deletion/ truncation mutations: 8% and 60%, and missense mutations: 10% and 64% at ages 30 and 50 years, respectively). Age related risks for haemangioblastoma were similar in the two mutation groups, with the age related risks of cerebellar haemangioblastoma slightly less (35% and 64% v 38% and 75% at ages 30 and 50 years) and retinal haemangioblastoma

  8. Two novel heterozygous missense variations within the GLI2 gene in two unrelated Argentine patients.

    PubMed

    Juanes, Matías; Di Palma, Isabel; Ciaccio, Marta; Marino, Roxana; Ramírez, Pablo C; Pérez Garrid, Natalia; Maceiras, Mercedes; Lazzati, Juan M; Rivarola, Marco A; Belgorosky, Alicia

    2016-01-01

    Several heterozygous GLI2 gene mutations have been reported in patients with isolated GH deficiency (IGHD) or multiple pituitary hormone deficiency (MPHD) with or without other malformations. The primary aim of this study was to analyze the presence of GLI2 gene alterations in a cohort of patients with IGHD or MPHD and ectopic/absent posterior pituitary. The coding sequence and flanking intronic regions of GLI2 gene were amplified and directly sequenced from gDNA of 18 affected subjects and relatives. In silico tools were applied to identify the functional impact of newly found variants (Polyphen2, SIFT, Mutation Taster). We identified two novel heterozygous missense variations in two unrelated patients, p.Arg231Gln and p.Arg226Leu, located in the repressor domain of the protein. Both variations affect highly conserved amino acids of the Gli2 protein and were not found in the available databases. In silico tools suggest that these variations might be disease causing. Our study suggests that the GLI2 gene may be one of the candidate genes to analyze when an association of pituitary hormone deficiency and developmental defects in posterior pituitary gland. The highly variable phenotype found suggests the presence of additional unknown factors that could contribute to the phenotype observed in these patients. PMID:27576279

  9. Structural and functional influences of coagulation factor XIII subunit B heterozygous missense mutants

    PubMed Central

    Thomas, Anne; Biswas, Arijit; Ivaskevicius, Vytautas; Oldenburg, Johannes

    2015-01-01

    The coagulation factor XIII(FXIII) is a plasma circulating heterotetrameric protransglutaminase that acts at the end of the coagulation cascade by covalently cross-linking preformed fibrin clots (to themselves and to fibrinolytic inhibitors) in order to stabilize them against fibrinolysis. It circulates in the plasma as a heterotetramer composed of two homomeric catalytic Factor XIIIA2 (FXIIIA2) and two homomeric protective/carrier Factor XIIIB2 subunit (FXIIIB2). Congenital deficiency of FXIII is of two types: severe homozygous/compound heterozygous FXIII deficiency which results in severe bleeding symptoms and mild heterozygous FXIII deficiency which is associated with mild bleeding (only upon trauma) or an asymptomatic phenotype. Defects in the F13B gene (Factor XIIIB subunit) occur more frequently in mild FXIII deficiency patients than in severe FXIII deficiency. We had recently reported secretion-related defects for seven previously reported F13B missense mutations. In the present study we further analyze the underlying molecular pathological mechanisms as well as the heterozygous expression phenotype for these mutations using a combination of in vitro heterologous expression (in HEK293T cells) and confocal microscopy. In combination with the in vitro work we have also performed an in silico solvated molecular dynamic simulation study on previously reported FXIIIB subunit sushi domain homology models in order to predict the putative structure-functional impact of these mutations. We were able to categorize the mutations into the following functional groups that: (1) affect antigenic stability as well as binding to FXIIIA subunit, that is, Cys5Arg, Cys316Phe, and Pro428Ser (2) affect binding to FXIIIA subunit with little or no influence on antigenic stability, that is, Ile81Asn and Val401Gln c) influence neither aspects and are most likely causality linked polymorphisms or functional polymorphisms, that is, Leu116Phe and Val217Ile. The Cys5Arg mutation was the

  10. Structural and functional influences of coagulation factor XIII subunit B heterozygous missense mutants.

    PubMed

    Thomas, Anne; Biswas, Arijit; Ivaskevicius, Vytautas; Oldenburg, Johannes

    2015-07-01

    The coagulation factor XIII(FXIII) is a plasma circulating heterotetrameric protransglutaminase that acts at the end of the coagulation cascade by covalently cross-linking preformed fibrin clots (to themselves and to fibrinolytic inhibitors) in order to stabilize them against fibrinolysis. It circulates in the plasma as a heterotetramer composed of two homomeric catalytic Factor XIIIA2 (FXIIIA2) and two homomeric protective/carrier Factor XIIIB2 subunit (FXIIIB2). Congenital deficiency of FXIII is of two types: severe homozygous/compound heterozygous FXIII deficiency which results in severe bleeding symptoms and mild heterozygous FXIII deficiency which is associated with mild bleeding (only upon trauma) or an asymptomatic phenotype. Defects in the F13B gene (Factor XIIIB subunit) occur more frequently in mild FXIII deficiency patients than in severe FXIII deficiency. We had recently reported secretion-related defects for seven previously reported F13B missense mutations. In the present study we further analyze the underlying molecular pathological mechanisms as well as the heterozygous expression phenotype for these mutations using a combination of in vitro heterologous expression (in HEK293T cells) and confocal microscopy. In combination with the in vitro work we have also performed an in silico solvated molecular dynamic simulation study on previously reported FXIIIB subunit sushi domain homology models in order to predict the putative structure-functional impact of these mutations. We were able to categorize the mutations into the following functional groups that: (1) affect antigenic stability as well as binding to FXIIIA subunit, that is, Cys5Arg, Cys316Phe, and Pro428Ser (2) affect binding to FXIIIA subunit with little or no influence on antigenic stability, that is, Ile81Asn and Val401Gln c) influence neither aspects and are most likely causality linked polymorphisms or functional polymorphisms, that is, Leu116Phe and Val217Ile. The Cys5Arg mutation was the

  11. Spectrum of mutations in alpha-mannosidosis.

    PubMed Central

    Berg, T; Riise, H M; Hansen, G M; Malm, D; Tranebjaerg, L; Tollersrud, O K; Nilssen, O

    1999-01-01

    alpha-Mannosidosis is an autosomal recessive disorder caused by deficiency of lysosomal alpha-mannosidase (LAMAN). The resulting intracellular accumulation of mannose-containing oligosaccharides leads to mental retardation, hearing impairment, skeletal changes, and immunodeficiency. Recently, we reported the first alpha-mannosidosis-causing mutation affecting two Palestinian siblings. In the present study 21 novel mutations and four polymorphic amino acid positions were identified by the screening of 43 patients, from 39 families, mainly of European origin. Disease-causing mutations were identified in 72% of the alleles and included eight splicing, six missense, and three nonsense mutations, as well as two small insertions and two small deletions. In addition, Southern blot analysis indicated rearrangements in some alleles. Most mutations were private or occurred in two or three families, except for a missense mutation resulting in an R750W substitution. This mutation was found in 13 patients, from different European countries, and accounted for 21% of the disease alleles. Although there were clinical variations among the patients, no significant LAMAN activity could be detected in any of the fibroblast cultures. In addition, no correlation between the types of mutations and the clinical manifestations was evident. PMID:9915946

  12. Prioritization of driver mutations in pancreatic cancer using cancer-specific high-throughput annotation of somatic mutations (CHASM).

    PubMed

    Carter, Hannah; Samayoa, Josue; Hruban, Ralph H; Karchin, Rachel

    2010-09-15

    Over 20,000 genes were recently sequenced in a series of 24 pancreatic cancers. We applied CHASM (Cancer-specific High-throughput Annotation of Somatic Mutations) to 963 of the missense somatic missense mutations discovered in these 24 cancers. CHASM identified putative driver mutations (false discovery rate ≤0.3) in three known pancreatic cancer driver genes (P53, SMAD4, CDKN2A). An additional 15 genes with putative driver mutations include genes coding for kinases (PIK3CG, DGKA, STK33, TTK and PRKCG), for cell cycle related proteins (NEK8), and for proteins involved in cell adhesion (CMAS, PCDHB2). These and other mutations identified by CHASM point to potential "driver genes" in pancreatic cancer that should be prioritized for additional follow-up. PMID:20581473

  13. Quantification of mutant E-cadherin using bioimaging analysis of in situ fluorescence microscopy. A new approach to CDH1 missense variants

    PubMed Central

    Sanches, João Miguel; Figueiredo, Joana; Fonseca, Martina; Durães, Cecília; Melo, Soraia; Esménio, Sofia; Seruca, Raquel

    2015-01-01

    Missense mutations result in full-length proteins containing an amino acid substitution that can be neutral or deleterious, interfering with the normal conformation, localization, and function of a protein. A striking example is the presence of CDH1 (E-cadherin gene) germline missense variants in hereditary diffuse gastric cancer (HDGC), which represent a clinical burden for genetic counseling and surveillance of mutation carriers and their families. CDH1 missense variants can compromise not only the function of E-cadherin but also its expression pattern. Here, we propose a novel method to characterize E-cadherin signature in order to identify cases with E-cadherin deregulation and functional impairment. The strategy includes a bioimaging pipeline to quantify the expression level and characterize the distribution of the protein from in situ immunofluorescence images. The algorithm computes 1D (dimension intensity) radial and internuclear fluorescence profiles to generate expression outlines and 2D virtual cells representing a typical cell within the populations analyzed. Using this new approach, we verify that cells expressing mutant forms of E-cadherin display fluorescence profiles distinct from those of the wild-type cells. Mutant proteins showed a significantly decrease of fluorescence intensity at the membrane and often abnormal expression peaks in the cytoplasm, reflecting the underlying molecular mechanism of trafficking deregulation. Our results suggest employing this methodology as a complementary approach to evaluate the pathogenicity of E-cadherin missense variants. Moreover, it can be applied to a wide range of proteins and, more importantly, to diseases characterized by aberrant protein expression or trafficking deregulation. PMID:25388006

  14. Quantification of mutant E-cadherin using bioimaging analysis of in situ fluorescence microscopy. A new approach to CDH1 missense variants.

    PubMed

    Sanches, João Miguel; Figueiredo, Joana; Fonseca, Martina; Durães, Cecília; Melo, Soraia; Esménio, Sofia; Seruca, Raquel

    2015-08-01

    Missense mutations result in full-length proteins containing an amino acid substitution that can be neutral or deleterious, interfering with the normal conformation, localization, and function of a protein. A striking example is the presence of CDH1 (E-cadherin gene) germline missense variants in hereditary diffuse gastric cancer (HDGC), which represent a clinical burden for genetic counseling and surveillance of mutation carriers and their families. CDH1 missense variants can compromise not only the function of E-cadherin but also its expression pattern. Here, we propose a novel method to characterize E-cadherin signature in order to identify cases with E-cadherin deregulation and functional impairment. The strategy includes a bioimaging pipeline to quantify the expression level and characterize the distribution of the protein from in situ immunofluorescence images. The algorithm computes 1D (dimension intensity) radial and internuclear fluorescence profiles to generate expression outlines and 2D virtual cells representing a typical cell within the populations analyzed. Using this new approach, we verify that cells expressing mutant forms of E-cadherin display fluorescence profiles distinct from those of the wild-type cells. Mutant proteins showed a significantly decrease of fluorescence intensity at the membrane and often abnormal expression peaks in the cytoplasm, reflecting the underlying molecular mechanism of trafficking deregulation. Our results suggest employing this methodology as a complementary approach to evaluate the pathogenicity of E-cadherin missense variants. Moreover, it can be applied to a wide range of proteins and, more importantly, to diseases characterized by aberrant protein expression or trafficking deregulation. PMID:25388006

  15. Novel Mutations in the Transcriptional Activator Domain of the Human TBX20 in Patients with Atrial Septal Defect

    PubMed Central

    Monroy-Muñoz, Irma Eloisa; Rodríguez-Pérez, José Manuel; Muñoz-Medina, José Esteban; Angeles-Martínez, Javier; García-Trejo, José J.; Morales-Ríos, Edgar; Massó, Felipe; Sandoval-Jones, Juan Pablo; Cervantes-Salazar, Jorge; García-Montes, José Antonio; Calderón-Colmenero, Juan; Vargas-Alarcón, Gilberto

    2015-01-01

    Background. The relevance of TBX20 gene in heart development has been demonstrated in many animal models, but there are few works that try to elucidate the effect of TBX20 mutations in human congenital heart diseases. In these studies, all missense mutations associated with atrial septal defect (ASD) were found in the DNA-binding T-box domain, none in the transcriptional activator domain. Methods. We search for TBX20 mutations in a group of patients with ASD or ventricular septal defect (VSD) using the High Resolution Melting (HRM) method and DNA sequencing. Results. We report three missense mutations (Y309D, T370O, and M395R) within the transcriptional activator domain of human TBX20 that were associated with ASD. Conclusions. This is the first association of TBX20 transcriptional activator domain missense mutations with ASD. These findings could have implications for diagnosis, genetic screening, and patient follow-up. PMID:25834824

  16. The SCN1A mutation database: updating information and analysis of the relationships among genotype, functional alteration, and phenotype.

    PubMed

    Meng, Heng; Xu, Hai-Qing; Yu, Lu; Lin, Guo-Wang; He, Na; Su, Tao; Shi, Yi-Wu; Li, Bin; Wang, Jie; Liu, Xiao-Rong; Tang, Bin; Long, Yue-Sheng; Yi, Yong-Hong; Liao, Wei-Ping

    2015-06-01

    Mutations in the SCN1A gene have been identified in epilepsy patients with widely variable phenotypes and modes of inheritance and in asymptomatic carriers. This raises challenges in evaluating the pathogenicity of SCN1A mutations. We systematically reviewed all SCN1A mutations and established a database containing information on functional alterations. In total, 1,257 mutations have been identified, of which 81.8% were not recurrent. There was a negative correlation between phenotype severity and missense mutation frequency. Further analyses suggested close relationships among genotype, functional alteration, and phenotype. Missense mutations located in different sodium channel regions were associated with distinct functional changes. Missense mutations in the pore region were characterized by the complete loss of function, similar to haploinsufficiency. Mutations with severe phenotypes were more frequently located in the pore region, suggesting that functional alterations are critical in evaluating pathogenicity and can be applied to patient management. A negative correlation was found between phenotype severity and familial incidence, and incomplete penetrance was associated with missense and splice site mutations, but not truncations or genomic rearrangements, suggesting clinical genetic counseling applications. Mosaic mutations with a load of 12.5-25.0% were potentially pathogenic with low penetrance, suggesting the need for future studies on less pathogenic genomic variations. PMID:25754450

  17. Novel POLG mutations in progressive external ophthalmoplegia mimicking mitochondrial neurogastrointestinal encephalomyopathy.

    PubMed

    Van Goethem, Gert; Schwartz, Marianne; Löfgren, Ann; Dermaut, Bart; Van Broeckhoven, Christine; Vissing, John

    2003-07-01

    Autosomal recessive progressive external ophthalmoplegia (PEO) is one clinical disorder associated with multiple mitochondrial DNA deletions and can be caused by missense mutations in POLG, the gene encoding the mitochondrial DNA polymerase gamma. Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is another autosomal recessive disorder associated with PEO and multiple deletions of mitochondrial DNA in skeletal muscle. In several patients this disorder is caused by loss of function mutations in the gene encoding thymidine phosphorylase (TP). We report a recessive family with features of MNGIE but no leukoencephalopathy in which two patients carry three missense mutations in POLG, of which two are novel mutations (N846S and P587L). The third mutation was previously reported as a recessive POLG mutation (T251I). This finding indicates the need for POLG sequencing in patients with features of MNGIE without TP mutations. PMID:12825077

  18. Novel PRKAR1A gene mutations in Carney Complex.

    PubMed

    Pan, Lorraine; Peng, Lan; Jean-Gilles, J; Zhang, Ximin; Wieczorek, Rosemary; Jain, Shilpa; Levine, Vicki; Osman, Iman; Prieto, Victor G; Lee, Peng

    2010-01-01

    Carney complex is a syndrome that may include cardiac and mucocutaneous myxomas, spotting skin pigmentation, and endocrine lesions. Many patients with Carney complex have been shown to have a stop codon mutation in the PRKAR1A gene in the 17q22-24 region. Here we present the case of a 57 year-old man with multiple skin lesions and cardiac myxomas. Histology of the skin lesions showed lentigenous melanocytic hyperplasia and cutaneous myxomas, confirming the diagnosis of Carney complex. Lesional and control normal tissue from the patient were identified and sequenced for the PRKAR1A gene. A germline missense mutation was identified at exon 1A. This is the first report of this mutation, and one of the few reported missense mutation associated with Carney complex. This finding strengthens the argument that there are alternative ways in which the protein kinase A 1-alpha subunit plays a role in tumorigenesis. PMID:20606737

  19. Mutation Update and Review of Severe Methylenetetrahydrofolate Reductase Deficiency.

    PubMed

    Froese, D Sean; Huemer, Martina; Suormala, Terttu; Burda, Patricie; Coelho, David; Guéant, Jean-Louis; Landolt, Markus A; Kožich, Viktor; Fowler, Brian; Baumgartner, Matthias R

    2016-05-01

    Severe 5,10-methylenetetrahydrofolate reductase (MTHFR) deficiency is caused by mutations in the MTHFR gene and results in hyperhomocysteinemia and varying severity of disease, ranging from neonatal lethal to adult onset. Including those described here, 109 MTHFR mutations have been reported in 171 families, consisting of 70 missense mutations, 17 that primarily affect splicing, 11 nonsense mutations, seven small deletions, two no-stop mutations, one small duplication, and one large duplication. Only 36% of mutations recur in unrelated families, indicating that most are "private." The most common mutation is c.1530A>G (numbered from NM_005957.4, p.Lys510 = ) causing a splicing defect, found in 13 families; the most common missense mutation is c.1129C>T (p.Arg377Cys) identified in 10 families. To increase disease understanding, we report enzymatic activity, detected mutations, and clinical onset information (early, <1 year; or late, >1 year) for all published patients available, demonstrating that patients with early onset have less residual enzyme activity than those presenting later. We also review animal models, diagnostic approaches, clinical presentations, and treatment options. This is the first large review of mutations in MTHFR, highlighting the wide spectrum of disease-causing mutations. PMID:26872964

  20. Patched homolog 1 gene mutation (p.G1093R) induces nevoid basal cell carcinoma syndrome and non-syndromic keratocystic odontogenic tumors: A case report

    PubMed Central

    PONTI, GIOVANNI; POLLIO, ANNAMARIA; PASTORINO, LORENZA; PELLACANI, GIOVANNI; MAGNONI, CRISTINA; NASTI, SABINA; FORTUNA, GIULIO; TOMASI, ALDO; SCARRÀ, GIOVANNA BIANCHI; SEIDENARI, STEFANIA

    2012-01-01

    Mutations in the Patched homolog 1 (PTCH1) gene lead to an autosomal dominant disorder known as nevoid basal cell carcinoma syndrome (NBCCS) or Gorlin syndrome (GS). Several PTCH1 mutations have been observed in NBCCS associated with keratocystic odontogenic tumors (KCOTs), including non-syndromic KCOTs. The missense mutation c.3277G>C (p.G1093R) in exon 19 of the PTCH1 gene has only been reported in non-syndromic KCOTs. The present study reports for the first time a familial case (father and daughter) of NBCCS and KCOTs, carrying the same c.3277G>C (p.G1093R) germline mutation. This observation suggests that this missense mutation is involved in the pathogenesis of NBCCS as well as in a subset of non-syndromic KCOTs. The identification of a missense mutation may lead to an earlier diagnosis of NBCCS. PMID:22844361

  1. Genotype-to-phenotype analysis: Search for clinical characteristics of a missense change in the GABA{sub A}-{beta}1 receptor gene

    SciTech Connect

    Sobell, J.L.; Sigurdson, D.C.; Sommer, S.S.

    1996-02-16

    Genotype-to-phenotype analysis reverses the classical approach to genetic disease in which an unknown genotype is sought for a known phenotype. This paper provides an example of genotype-to-phenotype analysis for the possible psychiatric effects of a missense mutation (H396Q) at a highly conserved residue of the {Beta}1 subunit gene of the gamma aminobutyric acid type A receptor. DNA samples from 1,507 Caucasians of Western European descent were screened, and 10 heterozygotes for H396Q were identified. These individuals were matched to homozygous normal individuals by age, gender, and length of available medical records. The complete medical records of these 20 individuals were reviewed blindly by two psychiatrists (D.C.S., L.L.H.) to assess psychiatric symptomatology, with an emphasis on anxiety and related disorders. However, no association was found between this missense change at a conserved amino acid and a dominant neuropsychiatric disease phenotype. Thus, this missense change may be neutral or only mildly deleterious, may only cause recessive disease in rare individuals, or may interact epistatically with some other gene(s). 17 refs.

  2. Vibratory Urticaria Associated with a Missense Variant in ADGRE2.

    PubMed

    Boyden, Steven E; Desai, Avanti; Cruse, Glenn; Young, Michael L; Bolan, Hyejeong C; Scott, Linda M; Eisch, A Robin; Long, R Daniel; Lee, Chyi-Chia R; Satorius, Colleen L; Pakstis, Andrew J; Olivera, Ana; Mullikin, James C; Chouery, Eliane; Mégarbané, André; Medlej-Hashim, Myrna; Kidd, Kenneth K; Kastner, Daniel L; Metcalfe, Dean D; Komarow, Hirsh D

    2016-02-18

    Patients with autosomal dominant vibratory urticaria have localized hives and systemic manifestations in response to dermal vibration, with coincident degranulation of mast cells and increased histamine levels in serum. We identified a previously unknown missense substitution in ADGRE2 (also known as EMR2), which was predicted to result in the replacement of cysteine with tyrosine at amino acid position 492 (p.C492Y), as the only nonsynonymous variant cosegregating with vibratory urticaria in two large kindreds. The ADGRE2 receptor undergoes autocatalytic cleavage, producing an extracellular subunit that noncovalently binds a transmembrane subunit. We showed that the variant probably destabilizes an autoinhibitory subunit interaction, sensitizing mast cells to IgE-independent vibration-induced degranulation. (Funded by the National Institutes of Health.). PMID:26841242

  3. Pathogenicity of the BRCA1 Missense Variant M1775K is Determined by the Disruption of the BRCT Phosphopeptide-Binding Pocket: a Multi-Modal Approach

    SciTech Connect

    Tischkowitz,M.; Hamel, N.; Carvalho, M.; Birrane, G.; Soni, A.; van Beers, E.; Joosse, S.; Wong, N.; Novak, D.; et al

    2008-01-01

    A number of germ-line mutations in the BRCA1 gene confer susceptibility to breast and ovarian cancer. However, it remains difficult to determine whether many single amino-acid (missense) changes in the BRCA1 protein that are frequently detected in the clinical setting are pathologic or not. Here, we used a combination of functional, crystallographic, biophysical, molecular and evolutionary techniques, and classical genetic segregation analysis to demonstrate that the BRCA1 missense variant M1775K is pathogenic. Functional assays in yeast and mammalian cells showed that the BRCA1 BRCT domains carrying the amino-acid change M1775K displayed markedly reduced transcriptional activity, indicating that this variant represents a deleterious mutation. Importantly, the M1775K mutation disrupted the phosphopeptide-binding pocket of the BRCA1 BRCT domains, thereby inhibiting the BRCA1 interaction with the proteins BRIP1 and CtIP, which are involved in DNA damage-induced checkpoint control. These results indicate that the integrity of the BRCT phosphopeptide-binding pocket is critical for the tumor suppression function of BRCA1. Moreover, this study demonstrates that multiple lines of evidence obtained from a combination of functional, structural, molecular and evolutionary techniques, and classical genetic segregation analysis are required to confirm the pathogenicity of rare variants of disease-susceptibility genes and obtain important insights into the underlying pathogenetic mechanisms.

  4. Na channel gene mutations in epilepsy--the functional consequences.

    PubMed

    Yamakawa, Kazuhiro

    2006-08-01

    Mutations of voltage-gated sodium channel genes SCN1A, SCN2A, and SCN1B have been identified in several types of epilepsies including generalized epilepsy with febrile seizures plus (GEFS+) and severe myoclonic epilepsy in infancy (SMEI). In both SCN1A and SCN2A, missense mutations tend to result in benign idiopathic epilepsy, whereas truncation mutations lead to severe and intractable epilepsy. However, the results obtained by the biophysical analyses using cultured cell systems still remain elusive. Now studies in animal models harboring sodium channel gene mutations should be eagerly pursued. PMID:16806834

  5. Mutations in argininosuccinate synthetase mRNA of Japanese patients, causing classical citrullinemia

    SciTech Connect

    Kobayashi, Keiko; Shaheen, Nazma; Terazono, Hiroki; Saheki, Takeyori

    1994-12-01

    Citrullinemia is an autosomal recessive disease caused by a genetic deficiency of argininosuccinate synthetase. In order to characterize mutations in Japanese patients with classical citrullinemia, RNA isolated from 10 unrelated patients was reverse-transcribed, and cDNA amplified by PCR was cloned and sequenced. The 10 mutations identified included 6 missense mutations (A118T, A192V, R272C, G280R, R304W, and R363L), 2 mutations associated with an absence of an exon 7 or exon 13, 1 mutation with a deletion of the first 7 bp in exon 16 (which might be caused by abnormal splicing), and 1 mutation with an insertion of 37 bp within exons 15 and 16 in cDNA. The insertion mutation and the five missense mutations (R304W being excluded) are new mutations described in the present paper. These are in addition to 14 mutations (9 missense mutations, 4 mutations associated with an absence of an exon in mRNA, and 1 splicing mutation) that we identified previously in mainly American patients with neonatal citrullinemia. Two of these 20 mutations, a deletion of exon 13 sequence and a 7-bp deletion in exon 16, were common to Japanese and American populations from different ethnic backgrounds; however, other mutations were unique to each population. Furthermore, the presence of a frequent mutation - the exon 7 deletion mutation in mRNA, which accounts for 10 of 23 affected alleles - was demonstrated in Japanese citrullinemia. This differs from the situation in the United States, where there was far greater heterogeneity of mutations.

  6. Functional Evaluation of Nine Missense-Type Variants of the Human DNA Glycosylase Enzyme MUTYH in the Japanese Population.

    PubMed

    Shinmura, Kazuya; Kato, Hisami; Goto, Masanori; Yamada, Hidetaka; Tao, Hong; Nakamura, Satoki; Sugimura, Haruhiko

    2016-04-01

    Biallelic germline mutations of MUTYH, the gene encoding DNA glycosylase, cause MUTYH-associated polyposis (MAP), characterized by multiple colorectal adenomas and carcinoma(s). However, a considerable number of MUTYH variants are still functionally uncharacterized. Herein, we report the results of functional evaluation of nine missense-type MUTYH variant proteins in the Japanese population. The DNA glycosylase activity and ability to suppress mutations caused by 8-hydroxyguanine, an oxidized form of guanine, were examined for the nine variants of type 2 MUTYH, a nuclear form of the enzyme, by DNA cleavage activity assay and supF forward mutation assay, respectively. Both activities were severely defective in the p.N210S MUTYH type 2 variant corresponding to p.N238S in the reference MUTYH form and partially defective in p.R219G variant corresponding to p.R247G, but nearly fully retained in seven other variants examined. Our results suggest that p.N238S and p.R247G are likely to be pathogenic alleles for MAP. PMID:26694661

  7. Next-generation sequencing identifies novel CACNA1A gene mutations in episodic ataxia type 2.

    PubMed

    Maksemous, Neven; Roy, Bishakha; Smith, Robert A; Griffiths, Lyn R

    2016-03-01

    Episodic Ataxia type 2 (EA2) is a rare autosomal dominantly inherited neurological disorder characterized by recurrent disabling imbalance, vertigo, and episodes of ataxia lasting minutes to hours. EA2 is caused most often by loss of function mutations of the calcium channel gene CACNA1A. In addition to EA2, mutations in CACNA1A are responsible for two other allelic disorders: familial hemiplegic migraine type 1 (FHM1) and spinocerebellar ataxia type 6 (SCA6). Herein, we have utilized next-generation sequencing (NGS) to screen the coding sequence, exon-intron boundaries, and Untranslated Regions (UTRs) of five genes where mutation is known to produce symptoms related to EA2, including CACNA1A. We performed this screening in a group of 31 unrelated patients with EA2 symptoms. Both novel and known mutations were detected through NGS technology, and confirmed through Sanger sequencing. Genetic testing showed in total 15 mutation bearing patients (48%), of which nine were novel mutations (6 missense and 3 small frameshift deletion mutations) and six known mutations (4 missense and 2 nonsense).These results demonstrate the efficiency of our NGS-panel for detecting known and novel mutations for EA2 in the CACNA1A gene, also identifying a novel missense mutation in ATP1A2 which is not a normal target for EA2 screening. PMID:27066515

  8. Missense Mutation in Exon 2 of SLC36A1 Responsible for Champagne Dilution in Horses

    PubMed Central

    Cook, Deborah; Brooks, Samantha; Bellone, Rebecca; Bailey, Ernest

    2008-01-01

    Champagne coat color in horses is controlled by a single, autosomal-dominant gene (CH). The phenotype produced by this gene is valued by many horse breeders, but can be difficult to distinguish from the effect produced by the Cream coat color dilution gene (CR). Three sires and their families segregating for CH were tested by genome scanning with microsatellite markers. The CH gene was mapped within a 6 cM region on horse chromosome 14 (LOD = 11.74 for θ = 0.00). Four candidate genes were identified within the region, namely SPARC [Secreted protein, acidic, cysteine-rich (osteonectin)], SLC36A1 (Solute Carrier 36 family A1), SLC36A2 (Solute Carrier 36 family A2), and SLC36A3 (Solute Carrier 36 family A3). SLC36A3 was not expressed in skin tissue and therefore not considered further. The other three genes were sequenced in homozygotes for CH and homozygotes for the absence of the dilution allele (ch). SLC36A1 had a nucleotide substitution in exon 2 for horses with the champagne phenotype, which resulted in a transition from a threonine amino acid to an arginine amino acid (T63R). The association of the single nucleotide polymorphism (SNP) with the champagne dilution phenotype was complete, as determined by the presence of the nucleotide variant among all 85 horses with the champagne dilution phenotype and its absence among all 97 horses without the champagne phenotype. This is the first description of a phenotype associated with the SLC36A1 gene. PMID:18802473

  9. S182 and STM2 gene missense mutations in sporadic alzheimer disease

    SciTech Connect

    Higuchi, Susumu; Matsushita, Sachio; Hasegawa, Yoshio; Muramatsu, Taro

    1996-07-26

    The linkage of genes S182 and STM2 to early-onset or late-onset sporadic Alzheimer disease (AD) was not found in a group of 97 clinically-diagnosed AD patients and 46 autopsy-confirmed AD cases, using PCR-RFLP methods. 7 refs.

  10. A missense mutation in TFRC, encoding transferrin receptor 1, causes combined immunodeficiency.

    PubMed

    Jabara, Haifa H; Boyden, Steven E; Chou, Janet; Ramesh, Narayanaswamy; Massaad, Michel J; Benson, Halli; Bainter, Wayne; Fraulino, David; Rahimov, Fedik; Sieff, Colin; Liu, Zhi-Jian; Alshemmari, Salem H; Al-Ramadi, Basel K; Al-Dhekri, Hasan; Arnaout, Rand; Abu-Shukair, Mohammad; Vatsayan, Anant; Silver, Eli; Ahuja, Sanjay; Davies, E Graham; Sola-Visner, Martha; Ohsumi, Toshiro K; Andrews, Nancy C; Notarangelo, Luigi D; Fleming, Mark D; Al-Herz, Waleed; Kunkel, Louis M; Geha, Raif S

    2016-01-01

    Patients with a combined immunodeficiency characterized by normal numbers but impaired function of T and B cells had a homozygous p.Tyr20His substitution in transferrin receptor 1 (TfR1), encoded by TFRC. The substitution disrupts the TfR1 internalization motif, resulting in defective receptor endocytosis and markedly increased TfR1 expression on the cell surface. Iron citrate rescued the lymphocyte defects, and expression of wild-type but not mutant TfR1 rescued impaired transferrin uptake in patient-derived fibroblasts. Tfrc(Y20H/Y20H) mice recapitulated the immunological defects of patients. Despite the critical role of TfR1 in erythrocyte development and function, patients had only mild anemia and only slightly increased TfR1 expression in erythroid precursors. We show that STEAP3, a metalloreductase expressed in erythroblasts, associates with TfR1 and partially rescues transferrin uptake in patient-derived fibroblasts, suggesting that STEAP3 may provide an accessory TfR1 endocytosis signal that spares patients from severe anemia. These findings demonstrate the importance of TfR1 in adaptive immunity. PMID:26642240

  11. Nemaline myopathy caused by mutations in the nebulin gene may present as a distal myopathy.

    PubMed

    Lehtokari, Vilma-Lotta; Pelin, Katarina; Herczegfalvi, Agnes; Karcagi, Veronika; Pouget, Jean; Franques, Jerôme; Pellissier, Jean François; Figarella-Branger, Dominique; von der Hagen, Maja; Huebner, Angela; Schoser, Benedikt; Lochmüller, Hanns; Wallgren-Pettersson, Carina

    2011-08-01

    Mutations in the nebulin gene are the main cause of autosomal recessive nemaline myopathy, with clinical presentations ranging from mild to severe disease. We have previously reported a nonspecific distal myopathy caused by homozygous missense mutations in the nebulin gene in six Finnish patients from four different families. Here we describe three non-Finnish patients in two unrelated families with distal nemaline myopathy caused by four different compound heterozygous nebulin mutations, only one of which is a missense mutation. One of the mutations has previously been identified in one family with the severe form of nemaline myopathy. We conclude that nemaline myopathy and distal myopathy caused by nebulin mutations form a clinical and histological continuum. Nemaline myopathy should be considered as a differential diagnosis in patients presenting with an early-onset predominantly distal myopathy. PMID:21724397

  12. Exome sequencing identifies PDE4D mutations in acrodysostosis.

    PubMed

    Lee, Hane; Graham, John M; Rimoin, David L; Lachman, Ralph S; Krejci, Pavel; Tompson, Stuart W; Nelson, Stanley F; Krakow, Deborah; Cohn, Daniel H

    2012-04-01

    Acrodysostosis is a dominantly-inherited, multisystem disorder characterized by skeletal, endocrine, and neurological abnormalities. To identify the molecular basis of acrodysostosis, we performed exome sequencing on five genetically independent cases. Three different missense mutations in PDE4D, which encodes cyclic AMP (cAMP)-specific phosphodiesterase 4D, were found to be heterozygous in three of the cases. Two of the mutations were demonstrated to have occurred de novo, providing strong genetic evidence of causation. Two additional cases were heterozygous for de novo missense mutations in PRKAR1A, which encodes the cAMP-dependent regulatory subunit of protein kinase A and which has been recently reported to be the cause of a form of acrodysostosis resistant to multiple hormones. These findings demonstrate that acrodysostosis is genetically heterogeneous and underscore the exquisite sensitivity of many tissues to alterations in cAMP homeostasis. PMID:22464252

  13. Novel mutations in 3-phosphoglycerate dehydrogenase (PHGDH) are distributed throughout the protein and result in altered enzyme kinetics.

    PubMed

    Tabatabaie, L; de Koning, T J; Geboers, A J J M; van den Berg, I E T; Berger, R; Klomp, L W J

    2009-05-01

    Three-phosphoglycerate dehydrogenase (3-PGDH) deficiency is a rare recessive inborn error in the biosynthesis of the amino acid L-serine characterized clinically by congenital microcephaly, psychomotor retardation, and intractable seizures. The biochemical abnormalities associated with this disorder are low concentrations of L-serine, D-serine, and glycine in cerebrospinal fluid (CSF). Only two missense mutations (p.V425M and p.V490M) have been identified in PHGDH, the gene encoding 3-PGDH, but it is currently unclear how these mutations in the carboxy-terminal regulatory domain of the protein affect enzyme function. We now describe five novel mutations in five patients with 3-PGDH deficiency; one frameshift mutation (p.G238fsX), and four missense mutations (p.R135W, p.V261M, p.A373T, and p.G377S). The missense mutations were located in the nucleotide binding and regulatory domains of 3-PGDH and did not affect steady-state expression, protein stability, and protein degradation rates. Patients' fibroblasts displayed a significant, but incomplete, reduction in maximal enzyme activities associated with all missense mutations. In transient overexpression studies in HEK293T cells, the p.A373T, p.V425M, and p.V490M mutations resulted in almost undetectable enzyme activities. Molecular modeling of the p.R135W and p.V261M mutations onto the partial crystal structure of 3-PGDH predicted that these mutations affect substrate and cofactor binding. This prediction was confirmed by the results of kinetic measurements in fibroblasts and transiently transfected HEK293T cells, which revealed a markedly decreased V(max) and an increase in K(m) values, respectively. Taken together, these data suggest that missense mutations associated with 3-PGDH deficiency either primarily affect substrate binding or result in very low residual enzymatic activity. PMID:19235232

  14. Rapid identification of HEXA mutations in Tay-Sachs patients.

    PubMed

    Giraud, Carole; Dussau, Jeanne; Azouguene, Emilie; Feillet, François; Puech, Jean-Philippe; Caillaud, Catherine

    2010-02-19

    Tay-Sachs disease (TSD) is a recessively inherited neurodegenerative disorder due to mutations in the HEXA gene resulting in a beta-hexosaminidase A (Hex A) deficiency. The purpose of this study was to characterize the molecular abnormalities in patients with infantile or later-onset forms of the disease. The complete sequencing of the 14 exons and flanking regions of the HEXA gene was performed with a unique technical condition in 10 unrelated TSD patients. Eleven mutations were identified, including five splice mutations, one insertion, two deletions and three single-base substitutions. Four mutations were novel: two splice mutations (IVS8+5G>A, IVS2+4delAGTA), one missense mutation in exon 6 (c.621T>G (p.D207E)) and one small deletion (c.1211-1212delTG) in exon 11 resulting in a premature stop codon at residue 429. The c.621T>G missense mutation was found in a patient presenting an infantile form. Its putative role in the pathogenesis of TSD is suspected as residue 207 is highly conserved in human, mouse and rat. Moreover, structural modelling predicted changes likely to affect substrate binding and catalytic activity of the enzyme. The time-saving procedure reported here could be useful for the characterization of Tay-Sachs-causing mutations, in particular in non-Ashkenazi patients mainly exhibiting rare mutations. PMID:20100466

  15. Identification and functional analysis of novel THAP1 mutations.

    PubMed

    Lohmann, Katja; Uflacker, Nils; Erogullari, Alev; Lohnau, Thora; Winkler, Susen; Dendorfer, Andreas; Schneider, Susanne A; Osmanovic, Alma; Svetel, Marina; Ferbert, Andreas; Zittel, Simone; Kühn, Andrea A; Schmidt, Alexander; Altenmüller, Eckart; Münchau, Alexander; Kamm, Christoph; Wittstock, Matthias; Kupsch, Andreas; Moro, Elena; Volkmann, Jens; Kostic, Vladimir; Kaiser, Frank J; Klein, Christine; Brüggemann, Norbert

    2012-02-01

    Mutations in THAP1 have been associated with dystonia 6 (DYT6). THAP1 encodes a transcription factor that represses the expression of DYT1. To further evaluate the mutational spectrum of THAP1 and its associated phenotype, we sequenced THAP1 in 567 patients with focal (n = 461), segmental (n = 68), or generalized dystonia (n = 38). We identified 10 novel variants, including six missense substitutions within the DNA-binding Thanatos-associated protein domain (Arg13His, Lys16Glu, His23Pro, Lys24Glu, Pro26Leu, Ile80Val), a 1bp-deletion downstream of the nuclear localization signal (Asp191Thrfs*9), and three alterations in the untranslated regions. The effect of the missense variants was assessed using prediction tools and luciferase reporter gene assays. This indicated the Ile80Val substitution as a benign variant. The subcellular localization of Asp191Thrfs*9 suggests a disturbed nuclear import for this mutation. Thus, we consider six of the 10 novel variants as pathogenic mutations accounting for a mutation frequency of 1.1%. Mutation carriers presented mainly with early onset dystonia (<12 years in five of six patients). Symptoms started in an arm or neck and spread to become generalized in three patients or segmental in two patients. Speech was affected in four mutation carriers. In conclusion, THAP1 mutations are rare in unselected dystonia patients and functional analysis is necessary to distinguish between benign variants and pathogenic mutations. PMID:21847143

  16. Identification and functional analysis of novel THAP1 mutations

    PubMed Central

    Lohmann, Katja; Uflacker, Nils; Erogullari, Alev; Lohnau, Thora; Winkler, Susen; Dendorfer, Andreas; Schneider, Susanne A; Osmanovic, Alma; Svetel, Marina; Ferbert, Andreas; Zittel, Simone; Kühn, Andrea A; Schmidt, Alexander; Altenmüller, Eckart; Münchau, Alexander; Kamm, Christoph; Wittstock, Matthias; Kupsch, Andreas; Moro, Elena; Volkmann, Jens; Kostic, Vladimir; Kaiser, Frank J; Klein, Christine; Brüggemann, Norbert

    2012-01-01

    Mutations in THAP1 have been associated with dystonia 6 (DYT6). THAP1 encodes a transcription factor that represses the expression of DYT1. To further evaluate the mutational spectrum of THAP1 and its associated phenotype, we sequenced THAP1 in 567 patients with focal (n=461), segmental (n=68), or generalized dystonia (n=38). We identified 10 novel variants, including six missense substitutions within the DNA-binding Thanatos-associated protein domain (Arg13His, Lys16Glu, His23Pro, Lys24Glu, Pro26Leu, Ile80Val), a 1bp-deletion downstream of the nuclear localization signal (Asp191Thrfs*9), and three alterations in the untranslated regions. The effect of the missense variants was assessed using prediction tools and luciferase reporter gene assays. This indicated the Ile80Val substitution as a benign variant. The subcellular localization of Asp191Thrfs*9 suggests a disturbed nuclear import for this mutation. Thus, we consider six of the 10 novel variants as pathogenic mutations accounting for a mutation frequency of 1.1%. Mutation carriers presented mainly with early onset dystonia (<12 years in five of six patients). Symptoms started in an arm or neck and spread to become generalized in three patients or segmental in two patients. Speech was affected in four mutation carriers. In conclusion, THAP1 mutations are rare in unselected dystonia patients and functional analysis is necessary to distinguish between benign variants and pathogenic mutations. PMID:21847143

  17. Correlation between connexin 32 gene mutations and clinical phenotype in X-linked dominant Charcot-Marie-Tooth neuropathy

    SciTech Connect

    Ionasescu, V.; Ionasescu, R.; Searby, C.

    1996-06-14

    We studied the relationship between the genotype and clinical phenotype in 27 families with dominant X-linked Charcot-Marie-Tooth (CMTX1) neuropathy. Twenty-two families showed mutations in the coding region of the connexin32 (cx32) gene. The mutations include four nonsense mutations, eight missense mutations, two medium size deletions, and one insertion. Most missense mutations showed a mild clinical phenotype (five out of eight), whereas all nonsense mutations, the larger of the two deletions, and the insertion that produced frameshifts showed severe phenotypes. Five CMTX1 families with mild clinical phenotype showed no point mutations of the cx32 gene coding region. Three of these families showed positive genetic linkage with the markers of the Xq13.1 region. The genetic linkage of the remaining two families could not be evaluated because of their small size. 25 refs., 1 fig., 1 tab.

  18. SNP2Structure: A Public and Versatile Resource for Mapping and Three-Dimensional Modeling of Missense SNPs on Human Protein Structures

    PubMed Central

    Wang, Difei; Song, Lei; Singh, Varun; Rao, Shruti; An, Lin; Madhavan, Subha

    2015-01-01

    One of the long-standing challenges in biology is to understand how non-synonymous single nucleotide polymorphisms (nsSNPs) change protein structure and further affect their function. While it is impractical to solve all the mutated protein structures experimentally, it is quite feasible to model the mutated structures in silico. Toward this goal, we built a publicly available structure database resource (SNP2Structure, https://apps.icbi.georgetown.edu/snp2structure) focusing on missense mutations, msSNP. Compared with web portals with similar aims, SNP2Structure has the following major advantages. First, our portal offers direct comparison of two related 3D structures. Second, the protein models include all interacting molecules in the original PDB structures, so users are able to determine regions of potential interaction changes when a protein mutation occurs. Third, the mutated structures are available to download locally for further structural and functional analysis. Fourth, we used Jsmol package to display the protein structure that has no system compatibility issue. SNP2Structure provides reliable, high quality mapping of nsSNPs to 3D protein structures enabling researchers to explore the likely functional impact of human disease-causing mutations. PMID:26949480

  19. Spectrum of mutations in CRM-positive and CRM-reduced hemophilia A

    SciTech Connect

    McGinniss, M.J.; Kazazian, H.H. Jr.; Bi, L.; Antonarakis, S.E. ); Hoyer, L.W. ); Inaba, H. )

    1993-02-01

    Hemophilia A is due to the functional deficiency of factor VIII (FVIII, gene locus F8C). Although half the patients have no detectable FVIII protein in their plasma, the more rare patients ([approximately]5%) have normal levels of a dysfunctional FVIII and are termed cross-reacting material (CRM)-positive. More commonly ([approximately]45%), patients have plasma FVIII protein reduced to an extent roughly comparable to the level of FVIII activity and are designated CRM-reduced. We used denaturing gradient gel electrophoresis to screen for mutations within the F8C gene of 11 patients (6CRM-positive, 5 CRM-reduced) and identified 9 different mutations in 9 patients after analyses of all 26 exons, the promoter region, and the polyadenylation site. Six mutations have not been described previously. Five weree missense (Ser289Leu, Ser558Phe, Val634Ala, Val634Met, Asn1441Lys), and the sixth was a 3-bp deletion ([Delta]Phe652). A review of the literature and the assay of FVIII antigen in 5 hemophilia A patients with previously identified missense mutations from this laboratory yielded a total of 20 other unique CRM-reduced and CRM-positive mutations. Almost all CRM-positive/reduced mutations (24/26) were missense, and many (12/26) occurred at CpG dinucleotides. We examined 19 missense mutation for evolutionary conservation using the portions of the porcine and murine F8C sequences that are known, and 18/19 amino acid residue altered by mutation in these patients wer conserved. Almost 50% of mutations (11/26) clustered in the A2 domain, suggesting that this region is critical for the function of FVIII. The results indicate a nonrandom distribution of mutations and suggest that mutations in a limited number of FVIII regions may cause CRM-positive and CRM-reduced heomphilia A. 48 refs., 1 fig., 1 tab.

  20. In vitro secretion deficits are common among human coagulation factor XIII subunit B missense mutants: correlations with patient phenotypes and molecular models.

    PubMed

    Biswas, Arijit; Thomas, Anne; Bevans, Carville G; Ivaskevicius, Vytautas; Oldenburg, Johannes

    2013-11-01

    Coagulation factor XIII (FXIII) proenzyme circulates in plasma as a heterotetramer composed of two each of A and B subunits. Upon activation, the B subunits dissociate from the A subunit dimer, which gains transglutaminase activity to cross-link preformed fibrin clots increasing mechanical strength and resistance to degradation. The B subunits are thought to possess a carrier/protective function before FXIII activation. Mutations in either A or B subunits are associated with pathological patient phenotypes characterized by mild to severe bleeding. In vitro expression of FXIII B subunit (FXIIIB) missense variants in HEK293T cells revealed impaired secretion for all seven variants studied. To investigate the likely molecular environments of the missense residues, we created molecular models of individual FXIIIB Sushi domains using phylogenetically similar complement factor H Sushi domain structural templates. Assessment of the local molecular environments for the models suggested surface or buried positions for each mutant residue and possible pathological mechanisms. The in vitro expression system and in silico analytical methods and models we developed can be used to further investigate the molecular basis of FXIIIB mutation pathologies. PMID:23913518

  1. Arginine-Glycine Amidinotransferase Deficiency and Functional Characterization of Missense Variants in GATM.

    PubMed

    DesRoches, Caro-Lyne; Bruun, Theodora; Wang, Peixiang; Marshall, Christian R; Mercimek-Mahmutoglu, Saadet

    2016-09-01

    Arginine-glycine amidinotransferase (GATM) deficiency is an autosomal-recessive disorder caused by pathogenic variants in GATM. Clinical features include intellectual disability, hypotonia, and myopathy. Due to normal neurodevelopment in asymptomatic individuals on creatine monotherapy, GATM deficiency is a good candidate for newborn screening. To determine the carrier frequency of GATM deficiency, we performed functional characterization of rare missense variants in GATM reported as heterozygous in the Exome Variant Server database. To assess phenotype and genotype correlation, we developed a clinical severity scoring system. Two patients with mild phenotype had a nonsense missense variant. Severe phenotype was present in patients with missense as well as truncating variants. There seems to be no phenotype and genotype correlation. We cloned a novel GATM transcript. We found seven missense variants retaining 0% of wild-type GATM activity indicating putative pathogenicity. Based on our study results, high Genomic Evolutionary Rate Profiling conservation score, conserved amino acid substitution in species, and low allele frequency in exome databases would be the most sensitive in silico analysis tools to predict pathogenicity of missense variants. We present first study of the functional characterization of missense variants in GATM as well as clinical severity score of patients with GATM deficiency. PMID:27233232

  2. Clinicopathologic variability of the GRN A9D mutation, including amyotrophic lateral sclerosis

    PubMed Central

    Cannon, Ashley; Fujioka, Shinsuke; Rutherford, Nicola J.; Ferman, Tanis J.; Broderick, Daniel F.; Boylan, Kevin B.; Graff-Radford, Neill R.; Uitti, Ryan J.; Rademakers, Rosa; Wszolek, Zbigniew K.

    2013-01-01

    Objective: We examined the clinical and pathologic phenotypes of GRN mutation carriers with the pathogenic A9D (g.26C>A) missense mutation. Methods: Three patients with GRN A9D mutations were evaluated clinically and came to autopsy with subsequent neuropathologic examination. Results: The clinical diagnoses of patients with GRN A9D mutations were amyotrophic lateral sclerosis, atypical extrapyramidal disorder, and behavioral variant frontotemporal dementia. Immunohistochemistry for TAR DNA-binding protein 43 (TDP-43) revealed variability in morphology and distribution of pathology. One patient had notable involvement of motor neurons in the spinal cord as well as type B TDP-43, whereas 2 other patients had type A TDP-43. Conclusions: The clinical presentation of the GRN A9D missense mutation is not restricted to behavioral variant frontotemporal dementia and may include aphasia, extrapyramidal features, and, notably, amyotrophic lateral sclerosis. PMID:23596077

  3. A somatic truncating mutation in BRCA2 in a sporadic breast tumor

    SciTech Connect

    Weber, B.H.F.; Brohm, M.; Stec, I.

    1996-10-01

    Recently, a second susceptibility gene for hereditary breast and ovarian cancer, BRCA2, was cloned. The subsequent identification of heterozygous germ-line mutations confirmed its role as a predisposing factor in a subset of familial breast and ovarian cancer families. The possible involvement of BRCA2 in the sporadic forms of breast and ovarian tumors was addressed in three recent reports analyzing the gene for somatic mutations in 212 primary breast cancers and SS ovarian cancers. Although several alterations were identified, all except two changes were shown to represent germ-line mutations. Moreover, the two somatic BRCA2 alterations were found to be missense mutations resulting in a Asp309S-Glu change in one case and in a His2415Asn change in the other. Given the questionable effect of missense mutations on protein function, the role of BRCA2 in the carcinogenesis of sporadic breast tumors remains unclear. 10 refs., 1 fig.

  4. Characterization of the mutational landscape of anaplastic thyroid cancer via whole-exome sequencing

    PubMed Central

    Kunstman, John W.; Juhlin, C. Christofer; Goh, Gerald; Brown, Taylor C.; Stenman, Adam; Healy, James M.; Rubinstein, Jill C.; Choi, Murim; Kiss, Nimrod; Nelson-Williams, Carol; Mane, Shrikant; Rimm, David L.; Prasad, Manju L.; Höög, Anders; Zedenius, Jan; Larsson, Catharina; Korah, Reju; Lifton, Richard P.; Carling, Tobias

    2015-01-01

    Anaplastic thyroid carcinoma (ATC) is a frequently lethal malignancy that is often unresponsive to available therapeutic strategies. The tumorigenesis of ATC and its relationship to the widely prevalent well-differentiated thyroid carcinomas are unclear. We have analyzed 22 cases of ATC as well as 4 established ATC cell lines using whole-exome sequencing. A total of 2674 somatic mutations (121/sample) were detected. Ontology analysis revealed that the majority of variants aggregated in the MAPK, ErbB and RAS signaling pathways. Mutations in genes related to malignancy not previously associated with thyroid tumorigenesis were observed, including mTOR, NF1, NF2, MLH1, MLH3, MSH5, MSH6, ERBB2, EIF1AX and USH2A; some of which were recurrent and were investigated in 24 additional ATC cases and 8 ATC cell lines. Somatic mutations in established thyroid cancer genes were detected in 14 of 22 (64%) tumors and included recurrent mutations in BRAF, TP53 and RAS-family genes (6 cases each), as well as PIK3CA (2 cases) and single cases of CDKN1B, CDKN2C, CTNNB1 and RET mutations. BRAF V600E and RAS mutations were mutually exclusive; all ATC cell lines exhibited a combination of mutations in either BRAF and TP53 or NRAS and TP53. A hypermutator phenotype in two cases with >8 times higher mutational burden than the remaining mean was identified; both cases harbored unique somatic mutations in MLH mismatch-repair genes. This first comprehensive exome-wide analysis of the mutational landscape of ATC identifies novel genes potentially associated with ATC tumorigenesis, some of which may be targets for future therapeutic intervention. PMID:25576899

  5. The evaluation of tools used to predict the impact of missense variants is hindered by two types of circularity

    PubMed Central

    Grimm, Dominik G.; Azencott, Chloé-Agathe; Aicheler, Fabian; Gieraths, Udo; MacArthur, Daniel G.; Samocha, Kaitlin E.; Cooper, David N.; Stenson, Peter D.; Daly, Mark J.; Smoller, Jordan W.; Duncan, Laramie E.; Borgwardt, Karsten M.

    2015-01-01

    Prioritizing missense variants for further experimental investigation is a key challenge in current sequencing studies for exploring complex and Mendelian diseases. A large number of in silico tools have been employed for the task of pathogenicity prediction, including PolyPhen-2, SIFT, FatHMM, MutationTaster-2, MutationAssessor, CADD, LRT, phyloP and GERP++, as well as optimized methods of combining tool scores, such as Condel and Logit. Due to the wealth of these methods, an important practical question to answer is which of these tools generalize best, that is, correctly predict the pathogenic character of new variants. We here demonstrate in a study of ten tools on five datasets that such a comparative evaluation of these tools is hindered by two types of circularity: they arise due to (1) the same variants or (2) different variants from the same protein occurring both in the datasets used for training and for evaluation of these tools, which may lead to overly optimistic results. We show that comparative evaluations of predictors that do not address these types of circularity may erroneously conclude that circularity-confounded tools are most accurate among all tools, and may even outperform optimized combinations of tools. PMID:25684150

  6. The evaluation of tools used to predict the impact of missense variants is hindered by two types of circularity.

    PubMed

    Grimm, Dominik G; Azencott, Chloé-Agathe; Aicheler, Fabian; Gieraths, Udo; MacArthur, Daniel G; Samocha, Kaitlin E; Cooper, David N; Stenson, Peter D; Daly, Mark J; Smoller, Jordan W; Duncan, Laramie E; Borgwardt, Karsten M

    2015-05-01

    Prioritizing missense variants for further experimental investigation is a key challenge in current sequencing studies for exploring complex and Mendelian diseases. A large number of in silico tools have been employed for the task of pathogenicity prediction, including PolyPhen-2, SIFT, FatHMM, MutationTaster-2, MutationAssessor, Combined Annotation Dependent Depletion, LRT, phyloP, and GERP++, as well as optimized methods of combining tool scores, such as Condel and Logit. Due to the wealth of these methods, an important practical question to answer is which of these tools generalize best, that is, correctly predict the pathogenic character of new variants. We here demonstrate in a study of 10 tools on five datasets that such a comparative evaluation of these tools is hindered by two types of circularity: they arise due to (1) the same variants or (2) different variants from the same protein occurring both in the datasets used for training and for evaluation of these tools, which may lead to overly optimistic results. We show that comparative evaluations of predictors that do not address these types of circularity may erroneously conclude that circularity confounded tools are most accurate among all tools, and may even outperform optimized combinations of tools. PMID:25684150

  7. Bacteriophage lambda cro mutations: effects on activity and intracellular degradation.

    PubMed Central

    Pakula, A A; Young, V B; Sauer, R T

    1986-01-01

    Following random mutagenesis of the bacteriophage lambda cro gene, we have isolated missense mutations that affect approximately half of the 66 residue positions of Cro. About two-thirds of the mutations change residues involved in the maintenance of Cro structure and stability. The corresponding mutant proteins are severely degraded in the cell but often have specific activities near that of wild-type Cro. The remaining mutations affect residues involved in DNA binding. These mutant proteins are present at moderately reduced intracellular levels, but their specific activities are much lower than that of wild type. Images PMID:2947238

  8. Truncating mutations in APP cause a distinct neurological phenotype.

    PubMed

    Klein, Steven; Goldman, Alexander; Lee, Hane; Ghahremani, Shahnaz; Bhakta, Viraj; Nelson, Stanley F; Martinez-Agosto, Julian A

    2016-09-01

    Dominant missense mutations in the amyloid β (Aβ) precursor protein (APP) gene have been implicated in early onset Alzheimer disease. These mutations alter protein structure to favor the pathologic production of Aβ. We report that homozygous nonsense mutations in APP are associated with decreased somatic growth, microcephaly, hypotonia, developmental delay, thinning of the corpus callosum, and seizures. We compare the phenotype of this case to those reported in mouse models and demonstrate multiple similarities, strengthening the role of amyloid precursor protein in normal brain function and development. Ann Neurol 2016;80:456-460. PMID:27422356

  9. Excess of De Novo Deleterious Mutations in Genes Associated with Glutamatergic Systems in Nonsyndromic Intellectual Disability

    PubMed Central

    Hamdan, Fadi F.; Gauthier, Julie; Araki, Yoichi; Lin, Da-Ting; Yoshizawa, Yuhki; Higashi, Kyohei; Park, A-Reum; Spiegelman, Dan; Dobrzeniecka, Sylvia; Piton, Amélie; Tomitori, Hideyuki; Daoud, Hussein; Massicotte, Christine; Henrion, Edouard; Diallo, Ousmane; Shekarabi, Masoud; Marineau, Claude; Shevell, Michael; Maranda, Bruno; Mitchell, Grant; Nadeau, Amélie; D'Anjou, Guy; Vanasse, Michel; Srour, Myriam; Lafrenière, Ronald G.; Drapeau, Pierre; Lacaille, Jean Claude; Kim, Eunjoon; Lee, Jae-Ran; Igarashi, Kazuei; Huganir, Richard L.; Rouleau, Guy A.; Michaud, Jacques L.

    2011-01-01

    Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder. PMID:21376300

  10. Excess of de novo deleterious mutations in genes associated with glutamatergic systems in nonsyndromic intellectual disability.

    PubMed

    Hamdan, Fadi F; Gauthier, Julie; Araki, Yoichi; Lin, Da-Ting; Yoshizawa, Yuhki; Higashi, Kyohei; Park, A-Reum; Spiegelman, Dan; Dobrzeniecka, Sylvia; Piton, Amélie; Tomitori, Hideyuki; Daoud, Hussein; Massicotte, Christine; Henrion, Edouard; Diallo, Ousmane; Shekarabi, Masoud; Marineau, Claude; Shevell, Michael; Maranda, Bruno; Mitchell, Grant; Nadeau, Amélie; D'Anjou, Guy; Vanasse, Michel; Srour, Myriam; Lafrenière, Ronald G; Drapeau, Pierre; Lacaille, Jean Claude; Kim, Eunjoon; Lee, Jae-Ran; Igarashi, Kazuei; Huganir, Richard L; Rouleau, Guy A; Michaud, Jacques L

    2011-03-11

    Little is known about the genetics of nonsyndromic intellectual disability (NSID). We hypothesized that de novo mutations (DNMs) in synaptic genes explain an important fraction of sporadic NSID cases. In order to investigate this possibility, we sequenced 197 genes encoding glutamate receptors and a large subset of their known interacting proteins in 95 sporadic cases of NSID. We found 11 DNMs, including ten potentially deleterious mutations (three nonsense, two splicing, one frameshift, four missense) and one neutral mutation (silent) in eight different genes. Calculation of point-substitution DNM rates per functional and neutral site showed significant excess of functional DNMs compared to neutral ones. De novo truncating and/or splicing mutations in SYNGAP1, STXBP1, and SHANK3 were found in six patients and are likely to be pathogenic. De novo missense mutations were found in KIF1A, GRIN1, CACNG2, and EPB41L1. Functional studies showed that all these missense mutations affect protein function in cell culture systems, suggesting that they may be pathogenic. Sequencing these four genes in 50 additional sporadic cases of NSID identified a second DNM in GRIN1 (c.1679_1681dup/p.Ser560dup). This mutation also affects protein function, consistent with structural predictions. None of these mutations or any other DNMs were identified in these genes in 285 healthy controls. This study highlights the importance of the glutamate receptor complexes in NSID and further supports the role of DNMs in this disorder. PMID:21376300

  11. Mutation spectrum of homogentisic acid oxidase (HGD) in alkaptonuria

    PubMed Central

    Vilboux, Thierry; Kayser, Michael; Introne, Wendy; Suwannarat, Pim; Bernardini, Isa; Fischer, Roxanne; O’Brien, Kevin; Kleta, Robert; Huizing, Marjan; Gahl, William A.

    2009-01-01

    Alkaptonuria (AKU) is a rare autosomal recessive metabolic disorder, characterized by accumulation of homogentisic acid, leading to darkened urine, pigmentation of connective tissue (ochronosis), joint and spine arthritis, and destruction of cardiac valves. AKU is due to mutations in the homogentisate dioxygenase gene, HGD, that converts homogentisic acid to maleylacetoacetic acid in the tyrosine catabolic pathway. Here we report a comprehensive mutation analysis of 93 patients enrolled in our study, as well as an extensive update of all previously published HGD mutations associated with AKU. Within our patient cohort, we identified 52 HGD variants, of which 22 were novel. This yields a total of 91 identified HGD variations associated with AKU to date, including 62 missense, 13 splice site, 10 frameshift, 5 nonsense and 1 no-stop mutation. Most HGD variants reside in exons 3, 6, 8 and 13. We assessed the potential effect of all missense variations on protein function, using 5 bioinformatic tools specifically designed for interpretation of missense variants (SIFT, POLYPHEN, PANTHER, PMUT and SNAP). We also analyzed the potential effect of splice site variants using two different tools (BDGP and NetGene2). This study provides valuable resources for molecular analysis of alkaptonuria and expands our knowledge of the molecular basis of this disease. PMID:19862842

  12. Novel pathogenic mutations and skin biopsy analysis in Knobloch syndrome

    PubMed Central

    Suzuki, Oscar; Kague, Erika; Bagatini, Kelly; Tu, Hongmin; Heljasvaara, Ritva; Carvalhaes, Lorenza; Gava, Elisandra; de Oliveira, Gisele; Godoi, Paulo; Oliva, Glaucius; Kitten, Gregory; Pihlajaniemi, Taina; Passos-Bueno, Maria-Rita

    2009-01-01

    Purpose To facilitate future diagnosis of Knobloch syndrome (KS) and better understand its etiology, we sought to identify not yet described COL18A1 mutations in KS patients. In addition, we tested whether mutations in this gene lead to absence of the COL18A1 gene product and attempted to better characterize the functional effect of a previously reported missense mutation. Methods Direct sequencing of COL18A1 exons was performed in KS patients from four unrelated pedigrees. We used immunofluorescent histochemistry in skin biopsies to evaluate the presence of type XVIII collagen in four KS patients carrying two already described mutations: c.3277C>T, a nonsense mutation, and c.3601G>A, a missense mutation. Furthermore, we determined the binding properties of the mutated endostatin domain p.A1381T (c.3601G>A) to extracellular matrix proteins using ELISA and surface plasmon resonance assays. Results We identified four novel mutations in COL18A1, including a large deletion involving exon 41. Skin biopsies from KS patients revealed lack of type XVIII collagen in epithelial basement membranes and blood vessels. We also found a reduced affinity of p.A1381T endostatin to some extracellular matrix components. Conclusions COL18A1 mutations involved in Knobloch syndrome have a distribution bias toward the coding exons of the C-terminal end. Large deletions must also be considered when point mutations are not identified in patients with characteristic KS phenotype. We report, for the first time, lack of type XVIII collagen in KS patients by immunofluorescent histochemistry in skin biopsy samples. As a final point, we suggest the employment of this technique as a preliminary and complementary test for diagnosis of KS in cases when mutation screening either does not detect mutations or reveals mutations of uncertain effect, such as the p.A1381T change. PMID:19390655

  13. Evidence for a founder effect of the germline fumarate hydratase gene mutation R58P causing hereditary leiomyomatosis and renal cell cancer (HLRCC).

    PubMed

    Heinritz, W; Paasch, U; Sticherling, M; Wittekind, C; Simon, J C; Froster, U G; Renner, R

    2008-01-01

    We report on the results of clinical investigation, pedigree analysis, mutation screening and haplotyping in a family with the syndrome of multiple cutaneous and uterine leiomyomas (MCUL1) and a germline missense mutation (R58P) in the fumarate hydratase gene (FH). We provide evidence for a founder effect for the identified mutation and distant relationship of our family to another familial case of MCUL1 associated with renal cell cancer, which was recently published with the same mutation. PMID:17908262

  14. Exome-Scale Discovery of Hotspot Mutation Regions in Human Cancer Using 3D Protein Structure.

    PubMed

    Tokheim, Collin; Bhattacharya, Rohit; Niknafs, Noushin; Gygax, Derek M; Kim, Rick; Ryan, Michael; Masica, David L; Karchin, Rachel

    2016-07-01

    The impact of somatic missense mutation on cancer etiology and progression is often difficult to interpret. One common approach for assessing the contribution of missense mutations in carcinogenesis is to identify genes mutated with statistically nonrandom frequencies. Even given the large number of sequenced cancer samples currently available, this approach remains underpowered to detect drivers, particularly in less studied cancer types. Alternative statistical and bioinformatic approaches are needed. One approach to increase power is to focus on localized regions of increased missense mutation density or hotspot regions, rather than a whole gene or protein domain. Detecting missense mutation hotspot regions in three-dimensional (3D) protein structure may also be beneficial because linear sequence alone does not fully describe the biologically relevant organization of codons. Here, we present a novel and statistically rigorous algorithm for detecting missense mutation hotspot regions in 3D protein structures. We analyzed approximately 3 × 10(5) mutations from The Cancer Genome Atlas (TCGA) and identified 216 tumor-type-specific hotspot regions. In addition to experimentally determined protein structures, we considered high-quality structural models, which increase genomic coverage from approximately 5,000 to more than 15,000 genes. We provide new evidence that 3D mutation analysis has unique advantages. It enables discovery of hotspot regions in many more genes than previously shown and increases sensitivity to hotspot regions in tumor suppressor genes (TSG). Although hotspot regions have long been known to exist in both TSGs and oncogenes, we provide the first report that they have different characteristic properties in the two types of driver genes. We show how cancer researchers can use our results to link 3D protein structure and the biologic functions of missense mutations in cancer, and to generate testable hypotheses about driver mechanisms. Our results

  15. Pyridoxine responsiveness in novel mutations of the PNPO gene

    PubMed Central

    Paul, Karl; Mills, Philippa; Clayton, Peter; Paschke, Eduard; Maier, Oliver; Hasselmann, Oswald; Schmiedel, Gudrun; Kanz, Simone; Connolly, Mary; Wolf, Nicole; Struys, Eduard; Stockler, Sylvia; Abela, Lucia; Hofer, Doris

    2014-01-01

    Objective: To determine whether patients with pyridoxine-responsive seizures but normal biomarkers for antiquitin deficiency and normal sequencing of the ALDH7A1 gene may have PNPO mutations. Methods: We sequenced the PNPO gene in 31 patients who fulfilled the above-mentioned criteria. Results: We were able to identify 11 patients carrying 3 novel mutations of the PNPO gene. In 6 families, a homozygous missense mutation p.Arg225His in exon 7 was identified, while 1 family was compound heterozygous for a novel missense mutation p.Arg141Cys in exon 5 and a deletion c.279_290del in exon 3. Pathogenicity of the respective mutations was proven by absence in 100 control alleles and expression studies in CHO-K1 cell lines. The response to pyridoxine was prompt in 4, delayed in 2, on EEG only in 2, and initially absent in another 2 patients. Two unrelated patients homozygous for the p.Arg225His mutation experienced status epilepticus when switched to pyridoxal 5′-phosphate (PLP). Conclusions: This study challenges the paradigm of exclusive PLP responsiveness in patients with pyridoxal 5′-phosphate oxidase deficiency and underlines the importance of consecutive testing of pyridoxine and PLP in neonates with antiepileptic drug–resistant seizures. Patients with pyridoxine response but normal biomarkers for antiquitin deficiency should undergo PNPO mutation analysis. PMID:24658933

  16. The spectrum of mutations causing end-plate acetylcholinesterase deficiency.

    PubMed

    Ohno, K; Engel, A G; Brengman, J M; Shen, X M; Heidenreich, F; Vincent, A; Milone, M; Tan, E; Demirci, M; Walsh, P; Nakano, S; Akiguchi, I

    2000-02-01

    The end-plate species of acetylcholinesterase (AChE) is an asymmetric enzyme consisting of a collagenic tail subunit composed of three collagenic strands (ColQ), each attached to a tetramer of the T isoform of the catalytic subunit (AChE(T)) via a proline-rich attachment domain. The principal function of the tail subunit is to anchor asymmetric AChE in the synaptic basal lamina. Human end-plate AChE deficiency was recently shown to be caused by mutations in COLQ. We here report nine novel COLQ mutations in 7 patients with end-plate AChE deficiency. We examine the effects of the mutations on the assembly of asymmetric AChE by coexpressing each genetically engineered COLQ mutant with ACHE(T) in COS cells. We classify the newly recognized and previously reported COLQ mutations into four classes according to their position in ColQ and their effect on AChE expression. We find that missense mutations in the proline-rich attachment domain abrogate attachment of catalytic subunits, that truncation mutations in the ColQ collagen domain prevent the assembly of asymmetric AChE, that hydrophobic missense residues in the C-terminal domain prevent triple helical assembly of the ColQ collagen domain, and that other mutations in the C-terminal region produce asymmetric species of AChE that are likely insertion incompetent. PMID:10665486

  17. Cross Talk Inhibition Nullified by a Receiver Domain Missense Substitution

    PubMed Central

    Huynh, TuAnh Ngoc; Lin, Hsia-Yin; Noriega, Chris E.; Lin, Alice V.

    2015-01-01

    inhibited in part by the high interaction specificity between cognate sensor-response regulator pairs. This study shows that a relatively subtle missense change from Val to Ala nullifies cross talk inhibition, enabling at least two noncognate sensors to enforce an inappropriate output independently of the relevant input. PMID:26260457

  18. Targeted next-generation sequencing extends the phenotypic and mutational spectrums for EYS mutations

    PubMed Central

    Gu, Shun; Tian, Yuanyuan; Chen, Xue

    2016-01-01

    Purpose We aim to determine genetic lesions with a phenotypic correlation in four Chinese families with autosomal recessive retinitis pigmentosa (RP). Methods Medical histories were carefully reviewed. All patients received comprehensive ophthalmic evaluations. The next-generation sequencing (NGS) approach targeting a panel of 205 retinal disease–relevant genes and 15 candidate genes was selectively performed on probands from the four recruited families for mutation detection. Online predictive software and crystal structure modeling were also applied to test the potential pathogenic effects of identified mutations. Results Of the four families, two were diagnosed with RP sino pigmento (RPSP). Patients with RPSP claimed to have earlier RP age of onset but slower disease progression. Five mutations in the eyes shut homolog (EYS) gene, involving two novel (c.7228+1G>A and c.9248G>A) and three recurrent mutations (c.4957dupA, c.6416G>A and c.6557G>A), were found as RP causative in the four families. The missense variant c.5093T>C was determined to be a variant of unknown significance (VUS) due to the variant’s colocalization in the same allele with the reported pathogenic mutation c.6416G>A. The two novel variants were further confirmed absent in 100 unrelated healthy controls. Online predictive software indicated potential pathogenicity of the three missense mutations. Further, crystal structural modeling suggested generation of two abnormal hydrogen bonds by the missense mutation p.G2186E (c.6557G>A) and elongation of its neighboring β-sheet induced by p.G3083D (c.9248G>A), which could alter the tertiary structure of the eys protein and thus interrupt its physicochemical properties. Conclusions Taken together, with the targeted NGS approach, we reveal novel EYS mutations and prove the efficiency of targeted NGS in the genetic diagnoses of RP. We also first report the correlation between EYS mutations and RPSP. The genotypic-phenotypic relationship in all

  19. Mutations in MECOM, Encoding Oncoprotein EVI1, Cause Radioulnar Synostosis with Amegakaryocytic Thrombocytopenia.

    PubMed

    Niihori, Tetsuya; Ouchi-Uchiyama, Meri; Sasahara, Yoji; Kaneko, Takashi; Hashii, Yoshiko; Irie, Masahiro; Sato, Atsushi; Saito-Nanjo, Yuka; Funayama, Ryo; Nagashima, Takeshi; Inoue, Shin-Ichi; Nakayama, Keiko; Ozono, Keiichi; Kure, Shigeo; Matsubara, Yoichi; Imaizumi, Masue; Aoki, Yoko

    2015-12-01

    Radioulnar synostosis with amegakaryocytic thrombocytopenia (RUSAT) is an inherited bone marrow failure syndrome, characterized by thrombocytopenia and congenital fusion of the radius and ulna. A heterozygous HOXA11 mutation has been identified in two unrelated families as a cause of RUSAT. However, HOXA11 mutations are absent in a number of individuals with RUSAT, which suggests that other genetic loci contribute to RUSAT. In the current study, we performed whole exome sequencing in an individual with RUSAT and her healthy parents and identified a de novo missense mutation in MECOM, encoding EVI1, in the individual with RUSAT. Subsequent analysis of MECOM in two other individuals with RUSAT revealed two additional missense mutations. These three mutations were clustered within the 8(th) zinc finger motif of the C-terminal zinc finger domain of EVI1. Chromatin immunoprecipitation and qPCR assays of the regions harboring the ETS-like motif that is known as an EVI1 binding site showed a reduction in immunoprecipitated DNA for two EVI1 mutants compared with wild-type EVI1. Furthermore, reporter assays showed that MECOM mutations led to alterations in both AP-1- and TGF-β-mediated transcriptional responses. These functional assays suggest that transcriptional dysregulation by mutant EVI1 could be associated with the development of RUSAT. We report missense mutations in MECOM resulting in a Mendelian disorder that provide compelling evidence for the critical role of EVI1 in normal hematopoiesis and in the development of forelimbs and fingers in humans. PMID:26581901

  20. Spectrum of AGL mutations in Chinese patients with glycogen storage disease type III: identification of 31 novel mutations.

    PubMed

    Lu, Chaoxia; Qiu, Zhengqing; Sun, Miao; Wang, Wei; Wei, Min; Zhang, Xue

    2016-07-01

    Glycogen storage disease type III (GSD III), a rare autosomal recessive disease characterized by hepatomegaly, fasting hypoglycemia, growth retardation, progressive myopathy and cardiomyopathy, is caused by deficiency of the glycogen debranching enzyme (AGL). Direct sequencing of human AGL cDNA and genomic DNA has enabled analysis of the underlying genetic defects responsible for GSD III. To date, the frequent mutations in different areas and populations have been described in Italy, Japan, Faroe Islands and Mediterranean area, whereas little has been performed in Chinese population. Here we report a sequencing-based mutation analysis in 43 Chinese patients with GSD III from 41 families. We identified 51 different mutations, including 15 splice-site (29.4%), 11 small deletions (21.6%), 12 nonsense (23.5%), 7 missense (13.7%), 5 duplication (9.8%) and 1 complex deletion/insertion (2.0%), 31 of which are novel mutations. The most common mutation is c.1735+1G>T (11.5%). The association of AGL missense and small in-frame deletion mutations with normal creatine kinase level was observed. Our study extends the spectrum of AGL mutations and suggests a genotype-phenotype correlation in GSD III. PMID:26984562

  1. Germ-line mutations of the APC gene in 53 familial adenomatous polyposis patients.

    PubMed Central

    Miyoshi, Y; Ando, H; Nagase, H; Nishisho, I; Horii, A; Miki, Y; Mori, T; Utsunomiya, J; Baba, S; Petersen, G

    1992-01-01

    We searched for germ-line mutations of the APC gene in 79 unrelated patients with familial adenomatous polyposis using a ribonuclease protection analysis coupled with polymerase chain reaction amplifications of genomic DNA. Mutations were found in 53 patients (67%); 28 of the mutations were small deletions and 2 were 1- to 2-base-pair insertions; 19 were point mutations resulting in stop codons and only 4 were missense point mutations. Thus, 92% of the mutations were predicted to result in truncations of the APC protein. More than two-thirds (68%) of the mutations were clustered in the 5' half of the last exon, and nearly two-fifths of the total mutations occurred at one of five positions. This information has significant implications for understanding the role of APC mutation in inherited forms of colorectal neoplasia and for designing effective methods for genetic counseling and presymptomatic diagnosis. Images PMID:1316610

  2. Mutations of the E-cadherin gene in human gynecologic cancers.

    PubMed

    Risinger, J I; Berchuck, A; Kohler, M F; Boyd, J

    1994-05-01

    Expression of the E-cadherin cell adhesion molecule is reduced in several types of human carcinomas, and the protein serves as an invasion suppressor in vitro. To determine if mutations of the E-cadherin gene (on chromosome 16q22) contribute to epithelial tumorigenesis, 135 carcinomas of the endometrium and ovary were examined for alterations in the E-cadherin coding region. Four mutations were identified: one somatic nonsense and one somatic missense mutation, both with retention of the wild-type alleles, and two missense mutations with somatic loss of heterozygosity in the tumour tissue. These data support the classification of E-cadherin as a human tumour suppressor gene. PMID:8075649

  3. Somatic mutations of the thyroid-stimulating hormone receptor gene in feline hyperthyroidism: parallels with human hyperthyroidism.

    PubMed

    Watson, S G; Radford, A D; Kipar, A; Ibarrola, P; Blackwood, L

    2005-09-01

    Hyperthyroidism is the most common endocrinopathy in cats, and is both clinically and histopathologically very similar to human toxic nodular goitre (TNG). Molecular studies on human TNG have revealed the presence of mis-sense mutations in the thyroid-stimulating hormone receptor (TSHR) gene, most frequently in exon 10. Our hypothesis was that similar mutations exist in hyperthyroid cats. Genomic DNA was extracted from 134 hyperplastic/adenomatous nodules (from 50 hyperthyroid cats), and analysed for the presence of mutations in exon 10 of the TSHR gene. 11 different mutations were detected, one silent and 10 mis-sense, of which nine were somatic mutations. 28 of the 50 cats (67/134 nodules) had at least one mis-sense mutation. The mis-sense mutations were Met-452-->Thr in 17 cats (35 nodules), Ser-504-->Arg (two different mutational forms) in two cats (two nodules), Val-508-->Arg in one cat (three nodules), Arg-530-->Gln in one cat (two nodules), Val-557-->Leu in 13 cats (36 nodules), Thr-631-->Ala or Thr-631-->Phe (each mutation seen in one nodule of one cat), Asp-632-->Tyr in six cats (10 nodules) and Asp-632-->His in one cat (one nodule). Five of these mutations have been associated previously with human hyperthyroidism. Of the 41 cats for which more than one nodule was available, 14 had nodules with different mutations. The identification of a potential genetic basis for feline hyperthyroidism is novel, increases our understanding of the pathogenesis of this significant feline disease, and confirms its similarity to TNG. PMID:16135672

  4. Heterozygous Reelin Mutations Cause Autosomal-Dominant Lateral Temporal Epilepsy

    PubMed Central

    Dazzo, Emanuela; Fanciulli, Manuela; Serioli, Elena; Minervini, Giovanni; Pulitano, Patrizia; Binelli, Simona; Di Bonaventura, Carlo; Luisi, Concetta; Pasini, Elena; Striano, Salvatore; Striano, Pasquale; Coppola, Giangennaro; Chiavegato, Angela; Radovic, Slobodanka; Spadotto, Alessandro; Uzzau, Sergio; La Neve, Angela; Giallonardo, Anna Teresa; Mecarelli, Oriano; Tosatto, Silvio C.E.; Ottman, Ruth; Michelucci, Roberto; Nobile, Carlo

    2015-01-01

    Autosomal-dominant lateral temporal epilepsy (ADLTE) is a genetic epilepsy syndrome clinically characterized by focal seizures with prominent auditory symptoms. ADLTE is genetically heterogeneous, and mutations in LGI1 account for fewer than 50% of affected families. Here, we report the identification of causal mutations in reelin (RELN) in seven ADLTE-affected families without LGI1 mutations. We initially investigated 13 ADLTE-affected families by performing SNP-array linkage analysis and whole-exome sequencing and identified three heterozygous missense mutations co-segregating with the syndrome. Subsequent analysis of 15 small ADLTE-affected families revealed four additional missense mutations. 3D modeling predicted that all mutations have structural effects on protein-domain folding. Overall, RELN mutations occurred in 7/40 (17.5%) ADLTE-affected families. RELN encodes a secreted protein, Reelin, which has important functions in both the developing and adult brain and is also found in the blood serum. We show that ADLTE-related mutations significantly decrease serum levels of Reelin, suggesting an inhibitory effect of mutations on protein secretion. We also show that Reelin and LGI1 co-localize in a subset of rat brain neurons, supporting an involvement of both proteins in a common molecular pathway underlying ADLTE. Homozygous RELN mutations are known to cause lissencephaly with cerebellar hypoplasia. Our findings extend the spectrum of neurological disorders associated with RELN mutations and establish a link between RELN and LGI1, which play key regulatory roles in both the developing and adult brain. PMID:26046367

  5. Molecular analysis of mucopolysaccharidosis IVA: Common mutations and racial difference

    SciTech Connect

    Tomatsu, S.; Hori, T.; Nakashima, Y.

    1994-09-01

    Mucopolysaccharidosis IVA (MPS IVA) is an autosomal recessive disorder caused by a deficiency in N-acetylgalactosamine -6-sulfate sulfatase (GALNS). Studies on the molecular basis of MPS IVA have been facilitated following cloning of the full-length cDNA and genomic DNA. In this study we detected mutations from 20 Caucasian and 19 Japanese MPS IVA patients using SSCP system and compared mutations of Caucasian origin with those of Japanese origin. The results showed the presence of 16 various mutations (3 small, deletions, 2 nonsense and 11 missense mutations) for Caucasian patients and 15 (1 deletion, 1 large alteration and 13 missense mutations) for Japanese. Moreover, two common mutations existed; one is double gene deletion characteristic for Japanese (6 alleles; 15%) and the other is a point mutation (1113F A{yields}T transition) characteristic for Caucasian (9 alleles; 22.5%). And the clear genotype/phenotype relationship among 1342delCA, IVS1(-2), P151S, Q148X, R386C, I113F, Q473X, W220G, P151L, A291T, R90W, and P77R, for a severe type, G96B N204K and V138A for a milder type, was observed. Only R386 mutation was seen in both of the populations. Further, the precise DNA analysis for double gene deletion of a common double gene deletion has been performed by defining the breakpoints and the results showed that one deletion was caused by homologous recombination due to Alu repetitive sequences and the other was due to nonhomologous recombination of short direct repeat. Haplotype analysis for six alleles with double deletion were different, indicating the different origin of this mutation or the frequent recombination events before a mutational event. Thus the mutations in GALNS gene are very heterogeneous and the racial difference is characteristic.

  6. Heterozygous reelin mutations cause autosomal-dominant lateral temporal epilepsy.

    PubMed

    Dazzo, Emanuela; Fanciulli, Manuela; Serioli, Elena; Minervini, Giovanni; Pulitano, Patrizia; Binelli, Simona; Di Bonaventura, Carlo; Luisi, Concetta; Pasini, Elena; Striano, Salvatore; Striano, Pasquale; Coppola, Giangennaro; Chiavegato, Angela; Radovic, Slobodanka; Spadotto, Alessandro; Uzzau, Sergio; La Neve, Angela; Giallonardo, Anna Teresa; Mecarelli, Oriano; Tosatto, Silvio C E; Ottman, Ruth; Michelucci, Roberto; Nobile, Carlo

    2015-06-01

    Autosomal-dominant lateral temporal epilepsy (ADLTE) is a genetic epilepsy syndrome clinically characterized by focal seizures with prominent auditory symptoms. ADLTE is genetically heterogeneous, and mutations in LGI1 account for fewer than 50% of affected families. Here, we report the identification of causal mutations in reelin (RELN) in seven ADLTE-affected families without LGI1 mutations. We initially investigated 13 ADLTE-affected families by performing SNP-array linkage analysis and whole-exome sequencing and identified three heterozygous missense mutations co-segregating with the syndrome. Subsequent analysis of 15 small ADLTE-affected families revealed four additional missense mutations. 3D modeling predicted that all mutations have structural effects on protein-domain folding. Overall, RELN mutations occurred in 7/40 (17.5%) ADLTE-affected families. RELN encodes a secreted protein, Reelin, which has important functions in both the developing and adult brain and is also found in the blood serum. We show that ADLTE-related mutations significantly decrease serum levels of Reelin, suggesting an inhibitory effect of mutations on protein secretion. We also show that Reelin and LGI1 co-localize in a subset of rat brain neurons, supporting an involvement of both proteins in a common molecular pathway underlying ADLTE. Homozygous RELN mutations are known to cause lissencephaly with cerebellar hypoplasia. Our findings extend the spectrum of neurological disorders associated with RELN mutations and establish a link between RELN and LGI1, which play key regulatory roles in both the developing and adult brain. PMID:26046367

  7. Mutations in Bruton's tyrosine kinase impair IgA responses.

    PubMed

    Mitsuiki, Noriko; Yang, Xi; Bartol, Sophinus J W; Grosserichter-Wagener, Christina; Kosaka, Yoshiyuki; Takada, Hidetoshi; Imai, Kohsuke; Kanegane, Hirokazu; Mizutani, Shuki; van der Burg, Mirjam; van Zelm, Menno C; Ohara, Osamu; Morio, Tomohiro

    2015-03-01

    X-linked agammaglobulinemia (XLA) is a primary immunodeficiency caused by mutations in Bruton's tyrosine kinase (BTK), and is characterized by markedly decreased numbers of blood B cells and an absence of all immunoglobulin isotypes. We performed whole exome sequencing in a male pediatric patient with dysgammaglobulinemia with IgA deficiency. Genetic analysis revealed a BTK missense mutation (Thr316Ala). To investigate whether a BTK mutation underlay this antibody deficiency with marked decrease of IgA in this patient, we performed functional analyses of B cells and phagocytes, and molecular analyses of somatic hypermutation and class switch recombination. The BTK missense mutation resulted in B cells with reduced BTK and high IgM expression. Equal proportions of CD19(low) and CD19(normal) fractions were observed, and both included naïve and memory B cells. Calcium influx and phospholipase Cγ2 phosphorylation upon IgM stimulation were marginally impaired in CD19(low), but not in CD19(+) B cells. Similar to XLA patients, IgA transcripts showed low SHM levels, whereas IgG transcripts were hardly affected. Our analyses suggest that the BTK mutation likely underlies the disease in this case, and that hypomorphic BTK mutations can result in normal circulating B cell numbers, but specifically impair IgA responses. PMID:25589397

  8. Hemophilia B: Molecular Pathogenesis and Mutation Analysis

    PubMed Central

    Goodeve, Anne C.

    2015-01-01

    Summary Hemophilia B is an X-chromosome-linked inherited bleeding disorder primarily affecting males, while those carrier females having reduced factor IX:C levels may also experience some bleeding issues. Genetic analysis has been undertaken for hemophilia B since the mid-1980s, both through linkage analysis to track inheritance of an affected allele and to enable determination of the familial mutation. Mutation analysis using PCR and Sanger sequencing along with dosage analysis for detection of large deletions/duplications enables mutation detection in more than 97% of hemophila B patients. Risk of inhibitory antibodies, reported in ~2% of hemophilia B patients can be predicted, especially in patients with large deletions and these individuals are also at risk of anaphylaxis, and nephrotic syndrome if they receive immune tolerance induction. Inhibitors also occur in patients with nonsense mutations, occasionally with small insertions/deletions, splice mutations and rarely with missense mutations (p.Gln237Lys and p.Gln241His). Hemophilia B results from several different mechanisms and those associated with hemophilia B Leyden, ribosome readthrough of nonsense mutations and apparently "silent" changes that do not alter amino acid coding are explored. Large databases of genetic variants in healthy individuals and patients with a range of disorders including hemophilia B are yielding useful information on sequence variant frequency to help establish possible variant pathogenicity whilst a growing range of algorithms is available to help predict pathogenicity for previously unreported variants. PMID:25851415

  9. High prevalence of mutations in peripherin/RDS in autosomal dominant macular dystrophies in a Spanish population

    PubMed Central

    Gamundi, María José; Hernan, Imma; Muntanyola, Marta; Trujillo, María José; García-Sandoval, Blanca; Ayuso, Carmen; Baiget, Montserrat

    2007-01-01

    Purpose Mutations in the peripherin/retinal degeneration slow (RDS) gene are a known cause of various types of central retinal dystrophies. The purpose of this study was to determine the prevalence of mutations in the peripherin/RDS gene in Spanish patients with different types of autosomal dominant macular dystrophy. Methods Ophthalmic and electrophysiological examination was performed in patients from 61 unrelated autosomal dominant macular dystrophy (adMD) Spanish families. Screening for mutations in the peripherin/RDS gene by denaturing gradient gel electrophoresis (DGGE) and direct genomic sequencing was performed in index patients and extended to the family when positive. Results We report four novel mutations in peripherin/RDS and a relatively high frequency (23%) of mutations in this gene in families with adMD. Thirteen different mutations were found in fifteen adMD families. Three novel missense, four nonsense and a cis-acting splicing mutation IVS2+2T>C, were found in a Spanish population while five more missense mutations were also reported in other populations. The Arg142Trp and Arg172Trp mutations, present in several populations, were both detected in two independent Spanish families. All the missense mutations produce an amino acid substitution in the second intradiscal loop of the peripherin, while the nonsense mutations presumably generate a truncated protein. Conclusions A high frequency (23%) of mutations in the peripherin/RDS gene was found in a cohort of 61 unrelated patients with various types of autosomal dominant central retinal dystrophies as compared with a low prevalence (1.3%) of mutations in this gene causing retinitis pigmentosa in a Spanish population. Different macular dystrophy phenotypes according to the mutations in peripherin/RDS are shown. However, a limited phenotype variation was observed for these mutations within the family. PMID:17653047

  10. Identification of the First De Novo UBIAD1 Gene Mutation Associated with Schnyder Corneal Dystrophy

    PubMed Central

    Chen, Judy L.

    2016-01-01

    Purpose. To report the identification of the first de novo UBIAD1 missense mutation in an individual with Schnyder corneal dystrophy (SCD). Methods. A slit lamp examination was performed on a 47-year-old woman without a family history of corneal disorders. The proband's parents, two sisters, and son were also examined and genomic DNA from all six individuals was collected. The exons and exon-intron boundaries of UBIAD1 were screened using Sanger sequencing. Identified mutations were screened for in 200 control chromosomes. In silico analysis predicted the impact of identified mutations on protein function and structure. Results. Slit lamp examination of the proband revealed findings consistent with SCD. Corneas of the family members appeared unaffected. Screening of UBIAD1 in the proband identified a novel heterozygous c.308C>T mutation, predicted to encode the missense amino acid substitution p.(Thr103Ile). This mutation was not identified in any of the family members or in 200 control chromosomes and was predicted to be damaging to normal protein function and structure. Conclusions. We present a novel heterozygous de novo missense mutation in UBIAD1, p.(Thr103Ile), identified in a patient with classic clinical features of SCD. This highlights the value of genetic testing in clinical diagnostic settings, even in the absence of a positive family history. PMID:27382485

  11. A Genome-wide Association Study of Nonsyndromic Cleft Palate Identifies an Etiologic Missense Variant in GRHL3.

    PubMed

    Leslie, Elizabeth J; Liu, Huan; Carlson, Jenna C; Shaffer, John R; Feingold, Eleanor; Wehby, George; Laurie, Cecelia A; Jain, Deepti; Laurie, Cathy C; Doheny, Kimberly F; McHenry, Toby; Resick, Judith; Sanchez, Carla; Jacobs, Jennifer; Emanuele, Beth; Vieira, Alexandre R; Neiswanger, Katherine; Standley, Jennifer; Czeizel, Andrew E; Deleyiannis, Frederic; Christensen, Kaare; Munger, Ronald G; Lie, Rolv T; Wilcox, Allen; Romitti, Paul A; Field, L Leigh; Padilla, Carmencita D; Cutiongco-de la Paz, Eva Maria C; Lidral, Andrew C; Valencia-Ramirez, Luz Consuelo; Lopez-Palacio, Ana Maria; Valencia, Dora Rivera; Arcos-Burgos, Mauricio; Castilla, Eduardo E; Mereb, Juan C; Poletta, Fernando A; Orioli, Iêda M; Carvalho, Flavia M; Hecht, Jacqueline T; Blanton, Susan H; Buxó, Carmen J; Butali, Azeez; Mossey, Peter A; Adeyemo, Wasiu L; James, Olutayo; Braimah, Ramat O; Aregbesola, Babatunde S; Eshete, Mekonen A; Deribew, Milliard; Koruyucu, Mine; Seymen, Figen; Ma, Lian; de Salamanca, Javier Enríquez; Weinberg, Seth M; Moreno, Lina; Cornell, Robert A; Murray, Jeffrey C; Marazita, Mary L

    2016-04-01

    Cleft palate (CP) is a common birth defect occurring in 1 in 2,500 live births. Approximately half of infants with CP have a syndromic form, exhibiting other physical and cognitive disabilities. The other half have nonsyndromic CP, and to date, few genes associated with risk for nonsyndromic CP have been characterized. To identify such risk factors, we performed a genome-wide association study of this disorder. We discovered a genome-wide significant association with a missense variant in GRHL3 (p.Thr454Met [c.1361C>T]; rs41268753; p = 4.08 × 10(-9)) and replicated the result in an independent sample of case and control subjects. In both the discovery and replication samples, rs41268753 conferred increased risk for CP (OR = 8.3, 95% CI 4.1-16.8; OR = 2.16, 95% CI 1.43-3.27, respectively). In luciferase transactivation assays, p.Thr454Met had about one-third of the activity of wild-type GRHL3, and in zebrafish embryos, perturbed periderm development. We conclude that this mutation is an etiologic variant for nonsyndromic CP and is one of few functional variants identified to date for nonsyndromic orofacial clefting. This finding advances our understanding of the genetic basis of craniofacial development and might ultimately lead to improvements in recurrence risk prediction, treatment, and prognosis. PMID:27018472

  12. Mutational analysis of STK11 gene in ovarian carcinomas.

    PubMed

    Nishioka, Y; Kobayashi, K; Sagae, S; Sugimura, M; Ishioka, S; Nagata, M; Terasawa, K; Tokino, T; Kudo, R

    1999-06-01

    Recently STK11, the causative gene of Peutz-Jeghers syndrome (PJS) was identified on chromosome 19p13.3. PJS is often accompanied by several malignancies, including breast tumor, adenoma malignum of the uterine cervix, and ovarian tumor. To investigate the involvement of STK11 gene in the development of ovarian carcinomas, we analyzed 30 ovarian carcinomas for loss of heterozygosity (LOH) and STK11 gene mutations. We found one missense mutation (codon 281, Pro to Leu) with heterozygous and somatic status. This mutation occurred at codon 281, which lies within the mutational hot spot (codon 279-281) of STK11 gene previously reported in PJS. We also detected LOH in 2 (11%) of 19 informative ovarian carcinomas. Our results suggest that mutations of the STK11 gene may play a limited role in the development of ovarian carcinomas. PMID:10429654

  13. Legius Syndrome: two novel mutations in the SPRED1 gene

    PubMed Central

    Bianchi, Marika; Saletti, Veronica; Micheli, Roberto; Esposito, Silvia; Molinaro, Anna; Gagliardi, Stella; Orcesi, Simona; Cereda, Cristina

    2015-01-01

    The SPRED1 gene encodes a protein involved in the Ras/MAPK (mitogen-activated protein kinase) signaling pathway. Mutations in SPRED1 have been reported to cause Legius Syndrome, a rare developmental disorder that shares some clinical features with Neurofibromatosis-1. Direct sequencing was used to define SPRED1 mutations. We present two previously undescribed mutations: a frameshift mutation causing a stop codon, which was identified in an Italian family (p.Ile60Tyrfs*18) and a missense variation, which was identified in one sporadic Italian case (p.Pro422Arg). Our results led us to hypothesize that these modifications may contribute to the Legius Syndrome phenotype. Further studies will be needed to determine the roles of these mutations in the mechanisms of Legius Syndrome. PMID:27081556

  14. Ten novel HMGCL mutations in 24 patients of different origin with 3-hydroxy-3-methyl-glutaric aciduria.

    PubMed

    Menao, Sebastián; López-Viñas, Eduardo; Mir, Cecilia; Puisac, Beatriz; Gratacós, Esther; Arnedo, María; Carrasco, Patricia; Moreno, Susana; Ramos, Mónica; Gil, María Concepción; Pié, Angeles; Ribes, Antonia; Pérez-Cerda, Celia; Ugarte, Magdalena; Clayton, Peter T; Korman, Stanley H; Serra, Dolors; Asins, Guillermina; Ramos, Feliciano J; Gómez-Puertas, Paulino; Hegardt, Fausto G; Casals, Nuria; Pié, Juan

    2009-03-01

    3-Hydroxy-3-methylglutaric aciduria is a rare autosomal recessive genetic disorder that affects ketogenesis and L-leucine catabolism. The clinical acute symptoms include vomiting, convulsions, metabolic acidosis, hypoketotic hypoglycaemia and lethargy. To date, 33 mutations in 100 patients have been reported in the HMGCL gene. In this study 10 new mutations in 24 patients are described. They include: 5 missense mutations: c.109G>A, c.425C>T, c.521G>A, c.575T>C and c.598A>T, 2 nonsense mutations: c.242G>A and c.559G>T, one small deletion: c.853delC, and 2 mutations in intron regions: c.497+4A>G and c.750+1G>A. Two prevalent mutations were detected, 109G>T (E37X) in 38% of disease alleles analyzed and c.504_505delCT in 10% of them. Although patients are mainly of European origin (71%) and mostly Spanish (54%), the group is ethnically diverse and includes, for the first time, patients from Pakistan, Palestine and Ecuador. We also present a simple, efficient method to express the enzyme and we analyze the possible functional effects of missense mutations. The finding that all identified missense mutations cause a >95% decrease in the enzyme activity, indicates that the disease appears only in very severe genotypes." PMID:19177531

  15. IDH1 and IDH2 mutations are frequent in Chinese patients with acute myeloid leukemia but rare in other types of hematological disorders.

    PubMed

    Zou, Yang; Zeng, Yun; Zhang, Deng-Feng; Zou, Shan-Hua; Cheng, Yun-Feng; Yao, Yong-Gang

    2010-11-12

    Frequent mutations in the isocitrate dehydrogenase 1 and 2 genes (IDH1 and IDH2) have been identified in gliomas and acute myeloid leukemia (AML). Our aim is to assess whether IDH mutations were presented in Chinese patients with various hematological disorders. In this study, we screened the IDH1 and IDH2 mutations in a cohort of 456 Chinese patients with various hematological malignancies and disorders. We found three missense (p.R132C, p.R132G, and p.I99M; occurred in five patients) and one silent mutation (c.315C>T; occurred in two patients) in the IDH1 gene and two missense mutations (p.R140Q and p.R172K; occurred in four AML patients) and one silent mutation (c.435G>A) in the IDH2 gene. Except for one non-Hodgkin lymphoma (NHL) patient harboring IDH1 mutation p.R132C, all IDH1 and IDH2 missense mutations were observed in patients with AML. Intriguingly, the IDH2 mutation p.R140Q and novel IDH1 mutation p.I99M co-occurred in a 75-year-old patient with AML developed from myelodysplastic syndromes (MDS). The frequency of IDH1 and IDH2 missense mutations in Chinese AML patients reached 5.9% and 8.3%, respectively. Our results supported the recent findings that IDH gene mutations were common in AML. Conversely, IDH mutations were rather rare in Chinese patients with other types of hematological disorders. PMID:20946881

  16. Domain-dependent clustering and genotype-phenotype analysis of LGI1 mutations in ADPEAF

    PubMed Central

    Ho, Yuan-Yuan; Ionita-Laza, Iuliana

    2012-01-01

    Objective: In families with autosomal dominant partial epilepsy with auditory features (ADPEAF) with mutations in the LGI1 gene, we evaluated clustering of mutations within the gene and associations of penetrance and phenotypic features with mutation location and predicted effect (truncation or missense). Methods: We abstracted clinical and molecular information from the literature for all 36 previously published ADPEAF families with LGI1 mutations. We used a sliding window approach to analyze mutation clustering within the gene. Each mutation was mapped to one of the gene's 2 major functional domains, N-terminal leucine-rich repeats (LRRs) and C-terminal epitempin (EPTP) repeats, and classified according to predicted effect on the encoded protein (truncation vs missense). Analyses of phenotypic features (age at onset and occurrence of auditory symptoms) in relation to mutation site and predicted effect included 160 patients with idiopathic focal unprovoked seizures from the 36 families. Results: ADPEAF-causing mutations clustered significantly in the LRR domain (exons 3–5) of LGI1 (p = 0.026). Auditory symptoms were less frequent in individuals with truncation mutations in the EPTP domain than in those with other mutation type/domain combinations (58% vs 80%, p = 0.018). Conclusion: The LRR region of the LGI1 gene is likely to play a major role in pathogenesis of ADPEAF. PMID:22323750

  17. Novel autosomal recessive gene mutations in aquaporin-2 in two Chinese congenital nephrogenic diabetes insipidus pedigrees

    PubMed Central

    Cen, Jing; Nie, Min; Duan, Lian; Gu, Feng

    2015-01-01

    Recent evidence has linked novel mutations in the arginine vasopressin receptor 2 gene (AVPR2) and aquaporin-2 gene (AQP2) present in Southeast Asian populations to congenital nephrogenic diabetes insipidus (NDI). To investigate mutations in 2 distinct Chinese pedigrees with NDI patients, clinical data, laboratory findings, and genomic DNA sequences from peripheral blood leukocytes were analyzed in two 5.5- and 8-year-old boys (proband 1 and 2, respectively) and their first-degree relatives. Water intake, urinary volume, body weight and medication use were recorded. Mutations in coding regions and intron-exon borders of both AQP2 and AVPR2 gene were sequenced. Three mutations in AQP2 were detected, including previously reported heterozygous frameshift mutation (c.127_128delCA, p.Gln43Aspfs ×63) inherited from the mother, a novel frameshift mutation (c.501_502insC, p.Val168Argfs ×30, inherited from the father) in proband 1 and a novel missense mutation (c. 643G>A, p. G215S), inherited from both parents in proband 2. In family 2 both parents and one sister were heterozygous carriers of the novel missense mutation. Neither pedigree exhibited mutation in the AVPR2 gene. The patient with truncated AQP2 may present with much more severe NDI manifestations. Identification of these novel AQP2 gene mutations expands the AQP2 genotypic spectrum and may contribute to etiological diagnosis and genetic counseling. PMID:26064258

  18. Identification of multiple ACVRL1 mutations in patients with pulmonary arterial hypertension by targeted exome capture.

    PubMed

    Piao, Chunmei; Zhu, Yan; Zhang, Chen; Xi, Xin; Liu, Xuxia; Zheng, Shuai; Li, Xiaoyan; Guo, Jun; Jia, Lixin; Nakanishi, Toshio; Cai, Tao; Gu, Hong; Du, Jie

    2016-09-01

    Pulmonary artery hypertension (PAH) is characterized as sustained elevation of pressure in the pulmonary vascular system that is attributable to a variety of causes. More than a dozen genes have previously been proposed as being associated with PAH. To examine potential mutations of these genes in patients with PAH, we developed a targeted exome kit containing 22 PAH-associated genes for genetic screens of 80 unrelated patients with PAH. As a result, we identified 16 different mutations in the BMPR2 gene and four different mutations in ACVRL1, the gene for activin receptor-like kinase-1 (ACVRL1). However, no deleterious mutations were found in the remaining 20 genes. In the present study, we provided detailed characterization of the ACVRL1 mutations in four pedigrees, including two novel missense mutations (c.676G>A, p.V226M; c.955G>C, p.G319R) and two recurrent mutations (c.1231C>T, p.R411W; c.1450C>T, p.R484W). Furthermore, we showed that markedly reduced Smad1/5 phosphorylation levels and reduced activities of luciferase reporters in each of the four ACVRL1 mutant-transfected NIH-3T3 cells. Therefore, our findings demonstrated that missense mutations of ACVRL1 identified in the present study significantly affected the bone morphogenetic protein 9 (BMP-9) pathway, implicating PAH pathogenesis. Detailed genotype-phenotype correlation analysis revealed initial symptoms of hereditary haemorrhagic telangiectasia (HHT) in some of the patients, suggesting the importance of sequencing molecular markers for early identification and intervention of individuals at risk for PAH and potential HHT. We developed a customized exome sequencing system to identify mutations in these PAH-associated genes, and found two novel missense mutations and two recurrent mutations in the ACVRL1 gene in four unrelated Chinese families; we also determined hypomorphic alleles using functional studies. PMID:27316748

  19. Novel KIF7 missense substitutions in two patients presenting with multiple malformations and features of acrocallosal syndrome.

    PubMed

    Tunovic, Sanjin; Barañano, Kristin W; Barkovich, James A; Strober, Jonathan B; Jamal, Leila; Slavotinek, Anne M

    2015-11-01

    We present two children who both had two missense mutations in the Kinesin Family Member 7 (KIF7) gene. A seven year old female with severe developmental delays, failure to thrive and growth retardation, infantile spasms, a cardiac vascular ring and right-sided aortic arch, imperforate anus, hydronephrosis with a right renal cyst, syndactyly and abnormal white matter was a compound heterozygote for c.3365C > G, predicting p.(Ser1122Trp) that was maternally inherited and c.2482G > A, predicting p.(Val828Met) that was paternally inherited. An eight year old female with severe developmental delays, epilepsy, left postaxial polydactyly of the hand and abnormalities of brain development including hydrocephalus, pachygyria and absence of the body and splenium of the corpus callous was a compound heterozygote for c.461G > A, predicting p.(Arg154Gln) and c.2959 G > A, predicting p.(Glu987Lys) that was maternally inherited and her father was unavailable for testing. The presentations in these children include features of acrocallosal syndrome, such as hypoplasia of the corpus callosum, enlarged ventricles, facial dysmorphism with a prominent forehead and broad halluces in the first child, but included atypical findings for individuals previously reported to have truncating mutations in KIF7, including imperforate anus, infantile spasms and severe growth retardation. We conclude that these phenotypes may result from the KIF7 sequence variants and abnormal hedgehog signaling, but that the full spectrum of KIF7-associated features remains to be determined. PMID:26174511

  20. AB125. Neonatal diabetes mellitus due to insulin gene mutation

    PubMed Central

    Can, Ngoc Thi Bich; Vu, Dung Chi; Bui, Thao Phuong; Nguyen, Khanh Ngoc; Nguyen, Dat Phu; Craig, Maria; Ellard, Sian; Nguyen, Hoan Thi

    2015-01-01

    Background and objective Insulin (INS) gene mutations that cause permanent neonatal diabetes mellitus change single protein building blocks (amino acids) in the protein sequence. These mutations are believed to disrupt the cleavage of the proinsulin chain or the binding of the A and B chains to form insulin, leading to impaired blood sugar control. At least ten mutations in the INS gene have been identified in people with permanent neonatal diabetes mellitus. To describe clinical features and laboratory manifestations of patients with INS gene mutation and to evaluate outcome of management. Methods Clinical features, biochemical finding, mutation analysis and management outcome of six cases from six unrelated families were study. All exons of INS gene were amplified from genomic DNA and directly sequenced. Results Six cases (three girls and three boys) onset at 129.2±128.8 days of age (median 101.5 days) with gestation age of 37.3±3.0 weeks, birth weight of 2,816.6±767.8 g. Five out of six patients admitted with the feature of diabetic ketoacidosis with pH of 7.04±0.22; plasma glucose levels were 34.3±12.7 mmoL/L, HbA1C of 9.75%±3.5%. Mutation analysis of the INS gene showed: heterozygous for a novel missense mutation (c.127T > A; C43S) in exon 2 in one case; heterozygous for a splicing mutation c.188-31G > A in intron 2 in two cases; heterozygous for a missense mutation c.286T > C in exon 3 in one case; heterozygous for a missense mutation c.265C > T [p.Arg89Cys (p.R89C)] in exon 3 in two cases. After 19.2±13.4 months of insulin treatment, 4/5 patients have normal development with DQ 80-100%, HbA1C of 6.85%±0.49%, quite normal blood glucose levels. The case with c.127T > A mutation treated with insulin for 14 years has physical development delay, poor blood glucose control with HbA1C of 11.4%. Conclusions It is important to perform screening gene mutation for patients with diabetes diagnosed before 6 months of age to control blood glucose and follow up the

  1. Weaver syndrome and EZH2 mutations: Clarifying the clinical phenotype.

    PubMed

    Tatton-Brown, Katrina; Murray, Anne; Hanks, Sandra; Douglas, Jenny; Armstrong, Ruth; Banka, Siddharth; Bird, Lynne M; Clericuzio, Carol L; Cormier-Daire, Valerie; Cushing, Tom; Flinter, Frances; Jacquemont, Marie-Line; Joss, Shelagh; Kinning, Esther; Lynch, Sally Ann; Magee, Alex; McConnell, Vivienne; Medeira, Ana; Ozono, Keiichi; Patton, Michael; Rankin, Julia; Shears, Debbie; Simon, Marleen; Splitt, Miranda; Strenger, Volker; Stuurman, Kyra; Taylor, Clare; Titheradge, Hannah; Van Maldergem, Lionel; Temple, I Karen; Cole, Trevor; Seal, Sheila; Rahman, Nazneen

    2013-12-01

    Weaver syndrome, first described in 1974, is characterized by tall stature, a typical facial appearance, and variable intellectual disability. In 2011, mutations in the histone methyltransferase, EZH2, were shown to cause Weaver syndrome. To date, we have identified 48 individuals with EZH2 mutations. The mutations were primarily missense mutations occurring throughout the gene, with some clustering in the SET domain (12/48). Truncating mutations were uncommon (4/48) and only identified in the final exon, after the SET domain. Through analyses of clinical data and facial photographs of EZH2 mutation-positive individuals, we have shown that the facial features can be subtle and the clinical diagnosis of Weaver syndrome is thus challenging, especially in older individuals. However, tall stature is very common, reported in >90% of affected individuals. Intellectual disability is also common, present in ~80%, but is highly variable and frequently mild. Additional clinical features which may help in stratifying individuals to EZH2 mutation testing include camptodactyly, soft, doughy skin, umbilical hernia, and a low, hoarse cry. Considerable phenotypic overlap between Sotos and Weaver syndromes is also evident. The identification of an EZH2 mutation can therefore provide an objective means of confirming a subtle presentation of Weaver syndrome and/or distinguishing Weaver and Sotos syndromes. As mutation testing becomes increasingly accessible and larger numbers of EZH2 mutation-positive individuals are identified, knowledge of the clinical spectrum and prognostic implications of EZH2 mutations should improve. PMID:24214728

  2. PRRT2 mutation in Japanese children with benign infantile epilepsy.

    PubMed

    Okumura, Akihisa; Shimojima, Keiko; Kubota, Tetsuo; Abe, Shinpei; Yamashita, Shintaro; Imai, Katsumi; Okanishi, Tohru; Enoki, Hideo; Fukasawa, Tatsuya; Tanabe, Takuya; Dibbens, Leanne M; Shimizu, Toshiaki; Yamamoto, Toshiyuki

    2013-08-01

    Mutations in PRRT2 genes have been identified as a major cause of benign infantile epilepsy and/or paroxysmal kinesigenic dyskinesia. We explored mutations in PRRT2 in Japanese patients with BIE as well as its related conditions including convulsion with mild gastroenteritis and benign early infantile epilepsy. We explored PRRT2 mutations in Japanese children who had had unprovoked infantile seizures or convulsion with mild gastroenteritis. The probands included 16 children with benign infantile epilepsy, 6 children with convulsions with mild gastroenteritis, and 2 siblings with benign early infantile epilepsy. In addition, we recruited samples from family members when PRRT2 mutation was identified in the proband. Statistical analyses were performed to identify differences in probands with benign infantile epilepsy according to the presence or absence of PRRT2 mutation. Among a total of 24 probands, PRRT2 mutations was identified only in 6 probands with benign infantile epilepsy. A common insertion mutation, c.649_650insC, was found in 5 families and a novel missense mutation, c.981C>G (I327M), in one. The family history of paroxysmal kinesigenic dyskinesia was more common in probands with PRRT2 mutations than in those without