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Sample records for mutation causing recessive

  1. Periaxin mutations cause recessive Dejerine-Sottas neuropathy.

    PubMed

    Boerkoel, C F; Takashima, H; Stankiewicz, P; Garcia, C A; Leber, S M; Rhee-Morris, L; Lupski, J R

    2001-02-01

    The periaxin gene (PRX) encodes two PDZ-domain proteins, L- and S-periaxin, that are required for maintenance of peripheral nerve myelin. Prx(-/-) mice develop a severe demyelinating peripheral neuropathy, despite apparently normal initial formation of myelin sheaths. We hypothesized that mutations in PRX could cause human peripheral myelinopathies. In accordance with this, we identified three unrelated Dejerine-Sottas neuropathy patients with recessive PRX mutations-two with compound heterozygous nonsense and frameshift mutations, and one with a homozygous frameshift mutation. We mapped PRX to 19q13.13-13.2, a region recently associated with a severe autosomal recessive demyelinating neuropathy in a Lebanese family (Delague et al. 2000) and syntenic to the location of Prx on murine chromosome 7 (Gillespie et al. 1997). PMID:11133365

  2. Mutations in NSUN2 Cause Autosomal- Recessive Intellectual Disability

    PubMed Central

    Abbasi-Moheb, Lia; Mertel, Sara; Gonsior, Melanie; Nouri-Vahid, Leyla; Kahrizi, Kimia; Cirak, Sebahattin; Wieczorek, Dagmar; Motazacker, M. Mahdi; Esmaeeli-Nieh, Sahar; Cremer, Kirsten; Weißmann, Robert; Tzschach, Andreas; Garshasbi, Masoud; Abedini, Seyedeh S.; Najmabadi, Hossein; Ropers, H. Hilger; Sigrist, Stephan J.; Kuss, Andreas W.

    2012-01-01

    With a prevalence between 1 and 3%, hereditary forms of intellectual disability (ID) are among the most important problems in health care. Particularly, autosomal-recessive forms of the disorder have a very heterogeneous molecular basis, and genes with an increased number of disease-causing mutations are not common. Here, we report on three different mutations (two nonsense mutations, c.679C>T [p.Gln227∗] and c.1114C>T [p.Gln372∗], as well as one splicing mutation, g.6622224A>C [p.Ile179Argfs∗192]) that cause a loss of the tRNA-methyltransferase-encoding NSUN2 main transcript in homozygotes. We identified the mutations by sequencing exons and exon-intron boundaries within the genomic region where the linkage intervals of three independent consanguineous families of Iranian and Kurdish origin overlapped with the previously described MRT5 locus. In order to gain further evidence concerning the effect of a loss of NSUN2 on memory and learning, we constructed a Drosophila model by deleting the NSUN2 ortholog, CG6133, and investigated the mutants by using molecular and behavioral approaches. When the Drosophila melanogaster NSUN2 ortholog was deleted, severe short-term-memory (STM) deficits were observed; STM could be rescued by re-expression of the wild-type protein in the nervous system. The humans homozygous for NSUN2 mutations showed an overlapping phenotype consisting of moderate to severe ID and facial dysmorphism (which includes a long face, characteristic eyebrows, a long nose, and a small chin), suggesting that mutations in this gene might even induce a syndromic form of ID. Moreover, our observations from the Drosophila model point toward an evolutionarily conserved role of RNA methylation in normal cognitive development. PMID:22541559

  3. Mutations in Citron Kinase Cause Recessive Microlissencephaly with Multinucleated Neurons.

    PubMed

    Harding, Brian N; Moccia, Amanda; Drunat, Séverine; Soukarieh, Omar; Tubeuf, Hélène; Chitty, Lyn S; Verloes, Alain; Gressens, Pierre; El Ghouzzi, Vincent; Joriot, Sylvie; Di Cunto, Ferdinando; Martins, Alexandra; Passemard, Sandrine; Bielas, Stephanie L

    2016-08-01

    Primary microcephaly is a neurodevelopmental disorder that is caused by a reduction in brain size as a result of defects in the proliferation of neural progenitor cells during development. Mutations in genes encoding proteins that localize to the mitotic spindle and centrosomes have been implicated in the pathogenicity of primary microcephaly. In contrast, the contractile ring and midbody required for cytokinesis, the final stage of mitosis, have not previously been implicated by human genetics in the molecular mechanisms of this phenotype. Citron kinase (CIT) is a multi-domain protein that localizes to the cleavage furrow and midbody of mitotic cells, where it is required for the completion of cytokinesis. Rodent models of Cit deficiency highlighted the role of this gene in neurogenesis and microcephaly over a decade ago. Here, we identify recessively inherited pathogenic variants in CIT as the genetic basis of severe microcephaly and neonatal death. We present postmortem data showing that CIT is critical to building a normally sized human brain. Consistent with cytokinesis defects attributed to CIT, multinucleated neurons were observed throughout the cerebral cortex and cerebellum of an affected proband, expanding our understanding of mechanisms attributed to primary microcephaly. PMID:27453579

  4. Recessive mutations in DGKE cause atypical hemolytic-uremic syndrome

    PubMed Central

    Lemaire, Mathieu; Frémeaux-Bacchi, Véronique; Schaefer, Franz; Choi, Murim; Tang, Wai Ho; Le Quintrec, Moglie; Fakhouri, Fadi; Taque, Sophie; Nobili, François; Martinez, Frank; Ji, Weizhen; Overton, John D.; Mane, Shrikant M.; Nürnberg, Gudrun; Altmüller, Janine; Thiele, Holger; Morin, Denis; Deschenes, Georges; Baudouin, Véronique; Llanas, Brigitte; Collard, Laure; Majid, Mohammed A.; Simkova, Eva; Nürnberg, Peter; Rioux-Leclerc, Nathalie; Moeckel, Gilbert W.; Gubler, Marie Claire; Hwa, John; Loirat, Chantal; Lifton, Richard P.

    2013-01-01

    Pathologic thrombosis is a major cause of mortality. Hemolytic-uremic syndrome (HUS) features episodes of small vessel thrombosis resulting in microangiopathic hemolytic anemia, thrombocytopenia and renal failure1. Atypical HUS (aHUS) can result from genetic or autoimmune factors2 that lead to pathologic complement cascade activation3. By exome sequencing we identify recessive mutations in DGKE (diacylglycerol kinase epsilon) that co-segregate with aHUS in 9 unrelated kindreds, defining a distinctive Mendelian disease. Affected patients present with aHUS before age 1, have persistent hypertension, hematuria and proteinuria (sometimes nephrotic range), and develop chronic kidney disease with age. DGKE is found in endothelium, platelets, and podocytes. Arachidonic acid-containing diacylglycerols (DAG) activate protein kinase C, which promotes thrombosis. DGKE normally inactivates DAG signaling. We infer that loss of DGKE function results in a pro-thrombotic state. These findings identify a new mechanism of pathologic thrombosis and kidney failure and have immediate implications for treatment of aHUS patients. PMID:23542698

  5. Infantile onset spinocerebellar ataxia caused by compound heterozygosity for Twinkle mutations and modeling of Twinkle mutations causing recessive disease

    PubMed Central

    Gulsuner, Suleyman; Stapleton, Gail A.; Walsh, Tom; Lee, Ming K.; Mandell, Jessica B.; Morales, Augusto; Klevit, Rachel E.; King, Mary-Claire; Rogers, R. Curtis

    2016-01-01

    Mutations in nuclear genes required for the replication and maintenance of mitochondrial DNA cause progressive multisystemic neuromuscular disorders with overlapping phenotypes. Biallelic mutations in C10orf2, encoding the Twinkle mitochondrial DNA helicase, lead to infantile-onset cerebellar ataxia (IOSCA), as well as milder and more severe phenotypes. We present a 13-year-old girl with ataxia, severe hearing loss, optic atrophy, peripheral neuropathy, and hypergonadotropic hypogonadism. Whole-exome sequencing revealed that the patient is compound heterozygous for previously unreported variants in the C10orf2 gene: a paternally inherited frameshift variant (c.333delT; p.L112Sfs*3) and a maternally inherited missense variant (c.904C>T; p.R302W). The identification of novel C10orf2 mutations extends the spectrum of mutations in the Twinkle helicase causing recessive disease, in particular the intermediate IOSCA phenotype. Structural modeling suggests that the p.R302W mutation and many other recessively inherited Twinkle mutations impact the position or interactions of the linker region, which is critical for the oligomeric ring structure and activity of the helicase. This study emphasizes the utility of whole-exome sequencing for the genetic diagnosis of a complex multisystemic disorder. PMID:27551684

  6. Infantile onset spinocerebellar ataxia caused by compound heterozygosity for Twinkle mutations and modeling of Twinkle mutations causing recessive disease.

    PubMed

    Pierce, Sarah B; Gulsuner, Suleyman; Stapleton, Gail A; Walsh, Tom; Lee, Ming K; Mandell, Jessica B; Morales, Augusto; Klevit, Rachel E; King, Mary-Claire; Rogers, R Curtis

    2016-07-01

    Mutations in nuclear genes required for the replication and maintenance of mitochondrial DNA cause progressive multisystemic neuromuscular disorders with overlapping phenotypes. Biallelic mutations in C10orf2, encoding the Twinkle mitochondrial DNA helicase, lead to infantile-onset cerebellar ataxia (IOSCA), as well as milder and more severe phenotypes. We present a 13-year-old girl with ataxia, severe hearing loss, optic atrophy, peripheral neuropathy, and hypergonadotropic hypogonadism. Whole-exome sequencing revealed that the patient is compound heterozygous for previously unreported variants in the C10orf2 gene: a paternally inherited frameshift variant (c.333delT; p.L112Sfs*3) and a maternally inherited missense variant (c.904C>T; p.R302W). The identification of novel C10orf2 mutations extends the spectrum of mutations in the Twinkle helicase causing recessive disease, in particular the intermediate IOSCA phenotype. Structural modeling suggests that the p.R302W mutation and many other recessively inherited Twinkle mutations impact the position or interactions of the linker region, which is critical for the oligomeric ring structure and activity of the helicase. This study emphasizes the utility of whole-exome sequencing for the genetic diagnosis of a complex multisystemic disorder. PMID:27551684

  7. ALDH1A3 mutations cause recessive anophthalmia and microphthalmia.

    PubMed

    Fares-Taie, Lucas; Gerber, Sylvie; Chassaing, Nicolas; Clayton-Smith, Jill; Hanein, Sylvain; Silva, Eduardo; Serey, Margaux; Serre, Valérie; Gérard, Xavier; Baumann, Clarisse; Plessis, Ghislaine; Demeer, Bénédicte; Brétillon, Lionel; Bole, Christine; Nitschke, Patrick; Munnich, Arnold; Lyonnet, Stanislas; Calvas, Patrick; Kaplan, Josseline; Ragge, Nicola; Rozet, Jean-Michel

    2013-02-01

    Anophthalmia and microphthalmia (A/M) are early-eye-development anomalies resulting in absent or small ocular globes, respectively. A/M anomalies occur in syndromic or nonsyndromic forms. They are genetically heterogeneous, some mutations in some genes being responsible for both anophthalmia and microphthalmia. Using a combination of homozygosity mapping, exome sequencing, and Sanger sequencing, we identified homozygosity for one splice-site and two missense mutations in the gene encoding the A3 isoform of the aldehyde dehydrogenase 1 (ALDH1A3) in three consanguineous families segregating A/M with occasional orbital cystic, neurological, and cardiac anomalies. ALDH1A3 is a key enzyme in the formation of a retinoic acid gradient along the dorso-ventral axis during early eye development. Transitory expression of mutant ALDH1A3 open reading frames showed that both missense mutations reduce the accumulation of the enzyme, potentially leading to altered retinoic acid synthesis. Although the role of retinoic acid signaling in eye development is well established, our findings provide genetic evidence of a direct link between retinoic-acid-synthesis dysfunction and early-eye-development anomalies in humans.

  8. 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

  9. Mutation of ATF6 causes autosomal recessive achromatopsia.

    PubMed

    Ansar, Muhammad; Santos-Cortez, Regie Lyn P; Saqib, Muhammad Arif Nadeem; Zulfiqar, Fareeha; Lee, Kwanghyuk; Ashraf, Naeem Mahmood; Ullah, Ehsan; Wang, Xin; Sajid, Sundus; Khan, Falak Sher; Amin-ud-Din, Muhammad; Smith, Joshua D; Shendure, Jay; Bamshad, Michael J; Nickerson, Deborah A; Hameed, Abdul; Riazuddin, Saima; Ahmed, Zubair M; Ahmad, Wasim; Leal, Suzanne M

    2015-09-01

    Achromatopsia (ACHM) is an early-onset retinal dystrophy characterized by photophobia, nystagmus, color blindness and severely reduced visual acuity. Currently mutations in five genes CNGA3, CNGB3, GNAT2, PDE6C and PDE6H have been implicated in ACHM. We performed homozygosity mapping and linkage analysis in a consanguineous Pakistani ACHM family and mapped the locus to a 15.12-Mb region on chromosome 1q23.1-q24.3 with a maximum LOD score of 3.6. A DNA sample from an affected family member underwent exome sequencing. Within the ATF6 gene, a single-base insertion variant c.355_356dupG (p.Glu119Glyfs*8) was identified, which completely segregates with the ACHM phenotype within the family. The frameshift variant was absent in public variant databases, in 130 exomes from unrelated Pakistani individuals, and in 235 ethnically matched controls. The variant is predicted to result in a truncated protein that lacks the DNA binding and transmembrane domains and therefore affects the function of ATF6 as a transcription factor that initiates the unfolded protein response during endoplasmic reticulum (ER) stress. Immunolabeling with anti-ATF6 antibodies showed localization throughout the mouse neuronal retina, including retinal pigment epithelium, photoreceptor cells, inner nuclear layer, inner and outer plexiform layers, with a more prominent signal in retinal ganglion cells. In contrast to cytoplasmic expression of wild-type protein, in heterologous cells ATF6 protein with the p.Glu119Glyfs*8 variant is mainly confined to the nucleus. Our results imply that response to ER stress as mediated by the ATF6 pathway is essential for color vision in humans. PMID:26063662

  10. Mutations in PNKP cause recessive ataxia with oculomotor apraxia type 4.

    PubMed

    Bras, Jose; Alonso, Isabel; Barbot, Clara; Costa, Maria Manuela; Darwent, Lee; Orme, Tatiana; Sequeiros, Jorge; Hardy, John; Coutinho, Paula; Guerreiro, Rita

    2015-03-01

    Hereditary autosomal-recessive cerebellar ataxias are a genetically and clinically heterogeneous group of disorders. We used homozygosity mapping and exome sequencing to study a cohort of nine Portuguese families who were identified during a nationwide, population-based, systematic survey as displaying a consistent phenotype of recessive ataxia with oculomotor apraxia (AOA). The integration of data from these analyses led to the identification of the same homozygous PNKP (polynucleotide kinase 3'-phosphatase) mutation, c.1123G>T (p.Gly375Trp), in three of the studied families. When analyzing this particular gene in the exome sequencing data from the remaining cohort, we identified homozygous or compound-heterozygous mutations in five other families. PNKP is a dual-function enzyme with a key role in different pathways of DNA-damage repair. Mutations in this gene have previously been associated with an autosomal-recessive syndrome characterized by microcephaly; early-onset, intractable seizures; and developmental delay (MCSZ). The finding of PNKP mutations associated with recessive AOA extends the phenotype associated with this gene and identifies a fourth locus that causes AOA. These data confirm that MCSZ and some forms of ataxia share etiological features, most likely reflecting the role of PNKP in DNA-repair mechanisms. PMID:25728773

  11. Mutations in PNKP cause recessive ataxia with oculomotor apraxia type 4.

    PubMed

    Bras, Jose; Alonso, Isabel; Barbot, Clara; Costa, Maria Manuela; Darwent, Lee; Orme, Tatiana; Sequeiros, Jorge; Hardy, John; Coutinho, Paula; Guerreiro, Rita

    2015-03-01

    Hereditary autosomal-recessive cerebellar ataxias are a genetically and clinically heterogeneous group of disorders. We used homozygosity mapping and exome sequencing to study a cohort of nine Portuguese families who were identified during a nationwide, population-based, systematic survey as displaying a consistent phenotype of recessive ataxia with oculomotor apraxia (AOA). The integration of data from these analyses led to the identification of the same homozygous PNKP (polynucleotide kinase 3'-phosphatase) mutation, c.1123G>T (p.Gly375Trp), in three of the studied families. When analyzing this particular gene in the exome sequencing data from the remaining cohort, we identified homozygous or compound-heterozygous mutations in five other families. PNKP is a dual-function enzyme with a key role in different pathways of DNA-damage repair. Mutations in this gene have previously been associated with an autosomal-recessive syndrome characterized by microcephaly; early-onset, intractable seizures; and developmental delay (MCSZ). The finding of PNKP mutations associated with recessive AOA extends the phenotype associated with this gene and identifies a fourth locus that causes AOA. These data confirm that MCSZ and some forms of ataxia share etiological features, most likely reflecting the role of PNKP in DNA-repair mechanisms.

  12. Mutations in PNKP Cause Recessive Ataxia with Oculomotor Apraxia Type 4

    PubMed Central

    Bras, Jose; Alonso, Isabel; Barbot, Clara; Costa, Maria Manuela; Darwent, Lee; Orme, Tatiana; Sequeiros, Jorge; Hardy, John; Coutinho, Paula; Guerreiro, Rita

    2015-01-01

    Hereditary autosomal-recessive cerebellar ataxias are a genetically and clinically heterogeneous group of disorders. We used homozygosity mapping and exome sequencing to study a cohort of nine Portuguese families who were identified during a nationwide, population-based, systematic survey as displaying a consistent phenotype of recessive ataxia with oculomotor apraxia (AOA). The integration of data from these analyses led to the identification of the same homozygous PNKP (polynucleotide kinase 3′-phosphatase) mutation, c.1123G>T (p.Gly375Trp), in three of the studied families. When analyzing this particular gene in the exome sequencing data from the remaining cohort, we identified homozygous or compound-heterozygous mutations in five other families. PNKP is a dual-function enzyme with a key role in different pathways of DNA-damage repair. Mutations in this gene have previously been associated with an autosomal-recessive syndrome characterized by microcephaly; early-onset, intractable seizures; and developmental delay (MCSZ). The finding of PNKP mutations associated with recessive AOA extends the phenotype associated with this gene and identifies a fourth locus that causes AOA. These data confirm that MCSZ and some forms of ataxia share etiological features, most likely reflecting the role of PNKP in DNA-repair mechanisms. PMID:25728773

  13. Mutations in MME cause an autosomal‐recessive Charcot–Marie–Tooth disease type 2

    PubMed Central

    Higuchi, Yujiro; Hashiguchi, Akihiro; Yuan, Junhui; Yoshimura, Akiko; Mitsui, Jun; Ishiura, Hiroyuki; Tanaka, Masaki; Ishihara, Satoshi; Tanabe, Hajime; Nozuma, Satoshi; Okamoto, Yuji; Matsuura, Eiji; Ohkubo, Ryuichi; Inamizu, Saeko; Shiraishi, Wataru; Yamasaki, Ryo; Ohyagi, Yasumasa; Kira, Jun‐ichi; Oya, Yasushi; Yabe, Hayato; Nishikawa, Noriko; Tobisawa, Shinsuke; Matsuda, Nozomu; Masuda, Masayuki; Kugimoto, Chiharu; Fukushima, Kazuhiro; Yano, Satoshi; Yoshimura, Jun; Doi, Koichiro; Nakagawa, Masanori; Morishita, Shinichi; Tsuji, Shoji

    2016-01-01

    Objective The objective of this study was to identify new causes of Charcot–Marie–Tooth (CMT) disease in patients with autosomal‐recessive (AR) CMT. Methods To efficiently identify novel causative genes for AR‐CMT, we analyzed 303 unrelated Japanese patients with CMT using whole‐exome sequencing and extracted recessive variants/genes shared among multiple patients. We performed mutation screening of the newly identified membrane metalloendopeptidase (MME) gene in 354 additional patients with CMT. We clinically, genetically, pathologically, and radiologically examined 10 patients with the MME mutation. Results We identified recessive mutations in MME in 10 patients. The MME gene encodes neprilysin (NEP), which is well known to be one of the most prominent beta‐amyloid (Aβ)‐degrading enzymes. All patients had a similar phenotype consistent with late‐onset axonal neuropathy. They showed muscle weakness, atrophy, and sensory disturbance in the lower extremities. All the MME mutations could be loss‐of‐function mutations, and we confirmed a lack/decrease of NEP protein expression in a peripheral nerve. No patients showed symptoms of dementia, and 1 patient showed no excess Aβ in Pittsburgh compound‐B positron emission tomography imaging. Interpretation Our results indicate that loss‐of‐function MME mutations are the most frequent cause of adult‐onset AR‐CMT2 in Japan, and we propose that this new disease should be termed AR‐CMT2T. A loss‐of‐function MME mutation did not cause early‐onset Alzheimer's disease. Identifying the MME mutation responsible for AR‐CMT could improve the rate of molecular diagnosis and the understanding of the molecular mechanisms of CMT. Ann Neurol 2016;79:659–672 PMID:26991897

  14. Recessive mutations in a distal PTF1A enhancer cause isolated pancreatic agenesis.

    PubMed

    Weedon, Michael N; Cebola, Inês; Patch, Ann-Marie; Flanagan, Sarah E; De Franco, Elisa; Caswell, Richard; Rodríguez-Seguí, Santiago A; Shaw-Smith, Charles; Cho, Candy H-H; Lango Allen, Hana; Houghton, Jayne A L; Roth, Christian L; Chen, Rongrong; Hussain, Khalid; Marsh, Phil; Vallier, Ludovic; Murray, Anna; Ellard, Sian; Ferrer, Jorge; Hattersley, Andrew T

    2014-01-01

    The contribution of cis-regulatory mutations to human disease remains poorly understood. Whole-genome sequencing can identify all noncoding variants, yet the discrimination of causal regulatory mutations represents a formidable challenge. We used epigenomic annotation in human embryonic stem cell (hESC)-derived pancreatic progenitor cells to guide the interpretation of whole-genome sequences from individuals with isolated pancreatic agenesis. This analysis uncovered six different recessive mutations in a previously uncharacterized ~400-bp sequence located 25 kb downstream of PTF1A (encoding pancreas-specific transcription factor 1a) in ten families with pancreatic agenesis. We show that this region acts as a developmental enhancer of PTF1A and that the mutations abolish enhancer activity. These mutations are the most common cause of isolated pancreatic agenesis. Integrating genome sequencing and epigenomic annotation in a disease-relevant cell type can thus uncover new noncoding elements underlying human development and disease. PMID:24212882

  15. Recessive mutations in a distal PTF1A enhancer cause isolated pancreatic agenesis

    PubMed Central

    Flanagan, Sarah E.; De Franco, Elisa; Caswell, Richard; Rodríguez-Seguí, Santiago A.; Shaw-Smith, Charles; Cho, Candy H-H.; Allen, Hana Lango; Houghton, Jayne AL.; Roth, Christian L.; Chen, Rongrong; Hussain, Khalid; Marsh, Phil; Vallier, Ludovic; Murray, Anna

    2014-01-01

    The contribution of cis-regulatory mutations to human disease remains poorly understood. Whole genome sequencing can identify all non-coding variants, yet discrimination of causal regulatory mutations represents a formidable challenge. We used epigenomic annotation in hESC-derived embryonic pancreatic progenitor cells to guide the interpretation of whole genome sequences from patients with isolated pancreatic agenesis. This uncovered six different recessive mutations in a previously uncharacterized ~400bp sequence located 25kb downstream of PTF1A (pancreas-specific transcription factor 1a) in ten families with pancreatic agenesis. We show that this region acts as a developmental enhancer of PTF1A and that the mutations abolish enhancer activity. These mutations are the most common cause of isolated pancreatic agenesis. Integrating genome sequencing and epigenomic annotation in a disease-relevant cell type can uncover novel non-coding elements underlying human development and disease. PMID:24212882

  16. Recessive mutations in ELOVL4 cause ichthyosis, intellectual disability, and spastic quadriplegia.

    PubMed

    Aldahmesh, Mohammed A; Mohamed, Jawahir Y; Alkuraya, Hisham S; Verma, Ishwar C; Puri, Ratna D; Alaiya, Ayodele A; Rizzo, William B; Alkuraya, Fowzan S

    2011-12-01

    Very-long-chain fatty acids (VLCFAs) play important roles in membrane structure and cellular signaling, and their contribution to human health is increasingly recognized. Fatty acid elongases catalyze the first and rate-limiting step in VLCFA synthesis. Heterozygous mutations in ELOVL4, the gene encoding one of the elongases, are known to cause macular degeneration in humans and retinal abnormalities in mice. However, biallelic ELOVL4 mutations have not been observed in humans, and murine models with homozygous mutations die within hours of birth as a result of a defective epidermal water barrier. Here, we report on two human individuals with recessive ELOVL4 mutations revealed by a combination of autozygome analysis and exome sequencing. These individuals exhibit clinical features of ichthyosis, seizures, mental retardation, and spasticity-a constellation that resembles Sjögren-Larsson syndrome (SLS) but presents a more severe neurologic phenotype. Our findings identify recessive mutations in ELOVL4 as the cause of a neuro-ichthyotic disease and emphasize the importance of VLCFA synthesis in brain and cutaneous development. PMID:22100072

  17. Mutations in the interleukin receptor IL11RA cause autosomal recessive Crouzon-like craniosynostosis.

    PubMed

    Keupp, Katharina; Li, Yun; Vargel, Ibrahim; Hoischen, Alexander; Richardson, Rebecca; Neveling, Kornelia; Alanay, Yasemin; Uz, Elif; Elcioğlu, Nursel; Rachwalski, Martin; Kamaci, Soner; Tunçbilek, Gökhan; Akin, Burcu; Grötzinger, Joachim; Konas, Ersoy; Mavili, Emin; Müller-Newen, Gerhard; Collmann, Hartmut; Roscioli, Tony; Buckley, Michael F; Yigit, Gökhan; Gilissen, Christian; Kress, Wolfram; Veltman, Joris; Hammerschmidt, Matthias; Akarsu, Nurten A; Wollnik, Bernd

    2013-11-01

    We have characterized a novel autosomal recessive Crouzon-like craniosynostosis syndrome in a 12-affected member family from Antakya, Turkey, the presenting features of which include: multiple suture synostosis, midface hypoplasia, variable degree of exophthalmos, relative prognathism, a beaked nose, and conductive hearing loss. Homozygosity mapping followed by targeted next-generation sequencing identified a c.479+6T>G mutation in the interleukin 11 receptor alpha gene (IL11RA) on chromosome 9p21. This donor splice-site mutation leads to a high percentage of aberrant IL11RA mRNA transcripts in an affected individual and altered mRNA splicing determined by in vitro exon trapping. An extended IL11RA mutation screen was performed in a cohort of 79 patients with an initial clinical diagnosis of Crouzon syndrome, pansynostosis, or unclassified syndromic craniosynostosis. We identified mutations segregating with the disease in five families: a German patient of Turkish origin and a Turkish family with three affected sibs all of whom were homozygous for the previously identified IL11RA c.479+6T>G mutation; a family with pansynostosis with compound heterozygous missense mutations, p.Pro200Thr and p.Arg237Pro; and two further Turkish families with Crouzon-like syndrome carrying the homozygous nonsense mutations p.Tyr232* and p.Arg292*. Using transient coexpression in HEK293T and COS7 cells, we demonstrated dramatically reduced IL11-mediated STAT3 phosphorylation for all mutations. Immunofluorescence analysis of mouse Il11ra demonstrated specific protein expression in cranial mesenchyme which was localized around the coronal suture tips and in the lambdoidal suture. In situ hybridization analysis of adult zebrafish also detected zfil11ra expression in the coronal suture between the overlapping frontal and parietal plates. This study demonstrates that mutations in the IL11RA gene cause an autosomal recessive Crouzon-like craniosynostosis. PMID:24498618

  18. Nephrocalcinosis (Enamel Renal Syndrome) Caused by Autosomal Recessive FAM20A Mutations

    PubMed Central

    Jaureguiberry, Graciana; De la Dure-Molla, Muriel; Parry, David; Quentric, Mickael; Himmerkus, Nina; Koike, Toshiyasu; Poulter, James; Klootwijk, Enriko; Robinette, Steven L.; Howie, Alexander J.; Patel, Vaksha; Figueres, Marie-Lucile; Stanescu, Horia C.; Issler, Naomi; Nicholson, Jeremy K.; Bockenhauer, Detlef; Laing, Christopher; Walsh, Stephen B.; McCredie, David A.; Povey, Sue; Asselin, Audrey; Picard, Arnaud; Coulomb, Aurore; Medlar, Alan J.; Bailleul-Forestier, Isabelle; Verloes, Alain; Le Caignec, Cedric; Roussey, Gwenaelle; Guiol, Julien; Isidor, Bertrand; Logan, Clare; Shore, Roger; Johnson, Colin; Inglehearn, Christopher; Al-Bahlani, Suhaila; Schmittbuhl, Matthieu; Clauss, François; Huckert, Mathilde; Laugel, Virginie; Ginglinger, Emmanuelle; Pajarola, Sandra; Spartà, Giuseppina; Bartholdi, Deborah; Rauch, Anita; Addor, Marie-Claude; Yamaguti, Paulo M.; Safatle, Heloisa P.; Acevedo, Ana Carolina; Martelli-Júnior, Hercílio; dos Santos Netos, Pedro E.; Coletta, Ricardo D.; Gruessel, Sandra; Sandmann, Carolin; Ruehmann, Denise; Langman, Craig B.; Scheinman, Steven J.; Ozdemir-Ozenen, Didem; Hart, Thomas C.; Hart, P. Suzanne; Neugebauer, Ute; Schlatter, Eberhard; Houillier, Pascal; Gahl, William A.; Vikkula, Miikka; Bloch-Zupan, Agnès; Bleich, Markus; Kitagawa, Hiroshi; Unwin, Robert J.; Mighell, Alan; Berdal, Ariane; Kleta, Robert

    2013-01-01

    Background/Aims Calcium homeostasis requires regulated cellular and interstitial systems interacting to modulate the activity and movement of this ion. Disruption of these systems in the kidney results in nephrocalcinosis and nephrolithiasis, important medical problems whose pathogenesis is incompletely understood. Methods We investigated 25 patients from 16 families with unexplained nephrocalcinosis and characteristic dental defects (amelogenesis imperfecta, gingival hyperplasia, impaired tooth eruption). To identify the causative gene, we performed genome-wide linkage analysis, exome capture, next-generation sequencing, and Sanger sequencing. Results All patients had bi-allelic FAM20A mutations segregating with the disease; 20 different mutations were identified. Conclusions This au-tosomal recessive disorder, also known as enamel renal syndrome, of FAM20A causes nephrocalcinosis and amelogenesis imperfecta. We speculate that all individuals with biallelic FAM20A mutations will eventually show nephrocalcinosis. PMID:23434854

  19. Candidate gene associated with a mutation causing recessive polycystic kidney disease in mice

    SciTech Connect

    Moyer, J.H.; Lee-Tischler, M.J.; Kwon, H.Y.; Schrick, J.J. ); Avner, E.D.; Sweeney, W.E. ); Godfrey, V.L.; Cacheiro, N.L.A.; Woychik, R.P. ); Wilkinson, J.E. )

    1994-05-27

    A line of transgenic mice was generated that contains an insertional mutation causing a phenotype similar to human autosomal recessive polycystic kidney disease. Homozygotes displayed a complex phenotype that included bilateral polycystic kidneys and an unusual liver lesion. The mutant locus was cloned and characterized through use of the transgene as a molecular marker. Additionally, a candidate polycystic kidney disease (PKD) gene was identified whose structure and expression are directly associated with the mutant locus. A complementary DNA derived from this gene predicted a peptide containing a motif that was originally identified in several genes involved in cell cycle control.

  20. Mutations in KLHL40 are a frequent cause of severe autosomal-recessive nemaline myopathy.

    PubMed

    Ravenscroft, Gianina; Miyatake, Satoko; Lehtokari, Vilma-Lotta; Todd, Emily J; Vornanen, Pauliina; Yau, Kyle S; Hayashi, Yukiko K; Miyake, Noriko; Tsurusaki, Yoshinori; Doi, Hiroshi; Saitsu, Hirotomo; Osaka, Hitoshi; Yamashita, Sumimasa; Ohya, Takashi; Sakamoto, Yuko; Koshimizu, Eriko; Imamura, Shintaro; Yamashita, Michiaki; Ogata, Kazuhiro; Shiina, Masaaki; Bryson-Richardson, Robert J; Vaz, Raquel; Ceyhan, Ozge; Brownstein, Catherine A; Swanson, Lindsay C; Monnot, Sophie; Romero, Norma B; Amthor, Helge; Kresoje, Nina; Sivadorai, Padma; Kiraly-Borri, Cathy; Haliloglu, Goknur; Talim, Beril; Orhan, Diclehan; Kale, Gulsev; Charles, Adrian K; Fabian, Victoria A; Davis, Mark R; Lammens, Martin; Sewry, Caroline A; Manzur, Adnan; Muntoni, Francesco; Clarke, Nigel F; North, Kathryn N; Bertini, Enrico; Nevo, Yoram; Willichowski, Ekkhard; Silberg, Inger E; Topaloglu, Haluk; Beggs, Alan H; Allcock, Richard J N; Nishino, Ichizo; Wallgren-Pettersson, Carina; Matsumoto, Naomichi; Laing, Nigel G

    2013-07-11

    Nemaline myopathy (NEM) is a common congenital myopathy. At the very severe end of the NEM clinical spectrum are genetically unresolved cases of autosomal-recessive fetal akinesia sequence. We studied a multinational cohort of 143 severe-NEM-affected families lacking genetic diagnosis. We performed whole-exome sequencing of six families and targeted gene sequencing of additional families. We identified 19 mutations in KLHL40 (kelch-like family member 40) in 28 apparently unrelated NEM kindreds of various ethnicities. Accounting for up to 28% of the tested individuals in the Japanese cohort, KLHL40 mutations were found to be the most common cause of this severe form of NEM. Clinical features of affected individuals were severe and distinctive and included fetal akinesia or hypokinesia and contractures, fractures, respiratory failure, and swallowing difficulties at birth. Molecular modeling suggested that the missense substitutions would destabilize the protein. Protein studies showed that KLHL40 is a striated-muscle-specific protein that is absent in KLHL40-associated NEM skeletal muscle. In zebrafish, klhl40a and klhl40b expression is largely confined to the myotome and skeletal muscle, and knockdown of these isoforms results in disruption of muscle structure and loss of movement. We identified KLHL40 mutations as a frequent cause of severe autosomal-recessive NEM and showed that it plays a key role in muscle development and function. Screening of KLHL40 should be a priority in individuals who are affected by autosomal-recessive NEM and who present with prenatal symptoms and/or contractures and in all Japanese individuals with severe NEM. PMID:23746549

  1. ALS5/SPG11/KIAA1840 mutations cause autosomal recessive axonal Charcot-Marie-Tooth disease.

    PubMed

    Montecchiani, Celeste; Pedace, Lucia; Lo Giudice, Temistocle; Casella, Antonella; Mearini, Marzia; Gaudiello, Fabrizio; Pedroso, José L; Terracciano, Chiara; Caltagirone, Carlo; Massa, Roberto; St George-Hyslop, Peter H; Barsottini, Orlando G P; Kawarai, Toshitaka; Orlacchio, Antonio

    2016-01-01

    Charcot-Marie-Tooth disease is a group of hereditary peripheral neuropathies that share clinical characteristics of progressive distal muscle weakness and atrophy, foot deformities, distal sensory loss, as well as diminished tendon reflexes. Hundreds of causative DNA changes have been found, but much of the genetic basis of the disease is still unexplained. Mutations in the ALS5/SPG11/KIAA1840 gene are a frequent cause of autosomal recessive hereditary spastic paraplegia with thin corpus callosum and peripheral axonal neuropathy, and account for ∼ 40% of autosomal recessive juvenile amyotrophic lateral sclerosis. The overlap of axonal Charcot-Marie-Tooth disease with both diseases, as well as the common autosomal recessive inheritance pattern of thin corpus callosum and axonal Charcot-Marie-Tooth disease in three related patients, prompted us to analyse the ALS5/SPG11/KIAA1840 gene in affected individuals with autosomal recessive axonal Charcot-Marie-Tooth disease. We investigated 28 unrelated families with autosomal recessive axonal Charcot-Marie-Tooth disease defined by clinical, electrophysiological, as well as pathological evaluation. Besides, we screened for all the known genes related to axonal autosomal recessive Charcot-Marie-Tooth disease (CMT2A2/HMSN2A2/MFN2, CMT2B1/LMNA, CMT2B2/MED25, CMT2B5/NEFL, ARCMT2F/dHMN2B/HSPB1, CMT2K/GDAP1, CMT2P/LRSAM1, CMT2R/TRIM2, CMT2S/IGHMBP2, CMT2T/HSJ1, CMTRID/COX6A1, ARAN-NM/HINT and GAN/GAN), for the genes related to autosomal recessive hereditary spastic paraplegia with thin corpus callosum and axonal peripheral neuropathy (SPG7/PGN, SPG15/ZFYVE26, SPG21/ACP33, SPG35/FA2H, SPG46/GBA2, SPG55/C12orf65 and SPG56/CYP2U1), as well as for the causative gene of peripheral neuropathy with or without agenesis of the corpus callosum (SLC12A6). Mitochondrial disorders related to Charcot-Marie-Tooth disease type 2 were also excluded by sequencing POLG and TYMP genes. An additional locus for autosomal recessive Charcot

  2. Autosomal recessive hypercholesterolemia caused by mutations in a putative LDL receptor adaptor protein.

    PubMed

    Garcia, C K; Wilund, K; Arca, M; Zuliani, G; Fellin, R; Maioli, M; Calandra, S; Bertolini, S; Cossu, F; Grishin, N; Barnes, R; Cohen, J C; Hobbs, H H

    2001-05-18

    Atherogenic low density lipoproteins are cleared from the circulation by hepatic low density lipoprotein receptors (LDLR). Two inherited forms of hypercholesterolemia result from loss of LDLR activity: autosomal dominant familial hypercholesterolemia (FH), caused by mutations in the LDLR gene, and autosomal recessive hypercholesterolemia (ARH), of unknown etiology. Here we map the ARH locus to an approximately 1-centimorgan interval on chromosome 1p35 and identify six mutations in a gene encoding a putative adaptor protein (ARH). ARH contains a phosphotyrosine binding (PTB) domain, which in other proteins binds NPXY motifs in the cytoplasmic tails of cell-surface receptors, including the LDLR. ARH appears to have a tissue-specific role in LDLR function, as it is required in liver but not in fibroblasts. PMID:11326085

  3. A Novel Recessive NEFL Mutation Causes a Severe, Early-Onset Axonal Neuropathy

    PubMed Central

    Yum, Sabrina W.; Zhang, Junxian; Mo, Katie; Li, Jian; Scherer, Steven S.

    2015-01-01

    Objective To report the first cases of homozygous recessive mutations in NEFL, the gene that encodes the light subunit of neurofilaments (NFL). Methods Clinical and electrophysiologic data of all family members were evaluated, and a sural nerve biopsy from one affected child was examined by immunohistochemistry and electron microscopy. The ability of the mutant protein to form filaments was characterized in an established cell culture system. Results Four of five siblings developed a severe, progressive neuropathy beginning in early childhood. Serial nerve conduction studies showed progressively reduced amplitudes with age, and pronounced slowing at all ages. Visual evoked responses were slowed in three children, indicating that CNS axons were subclinically involved. All four affected children were homozygous for a nonsense mutation at glutamate 210 (E210X) in the NEFL gene; both parents were heterozygous carriers. A sural nerve biopsy from an affected patient at age 16 revealed markedly reduced numbers of myelinated axons; the remaining myelinated axons were small and lacked intermediate filaments. The E210X mutant protein did not form an intermediate filament network, and did not interfere with the filament formation by wild type human NFL in SW-13 vim- cells. Interpretation This is the first demonstration of a recessive NEFL mutation, which appears to cause a simple loss-of-function, resulting in a severe, early-onset axonal neuropathy with unique features. These results confirm that neurofilaments are the main determinant of axonal caliber and conduction velocity, and demonstrate for the first time that neurofilaments are required for the maintenance of myelinated PNS axons. PMID:20039262

  4. A novel homozygous mutation in HSF4 causing autosomal recessive congenital cataract.

    PubMed

    Behnam, Mahdiyeh; Imagawa, Eri; Chaleshtori, Ahmad Reza Salehi; Ronasian, Firooze; Salehi, Mansoor; Miyake, Noriko; Matsumoto, Naomichi

    2016-02-01

    Cataract is defined as opacity in the crystalline lens and congenital cataract occurs during the first year of life. Until now, mutations of more than 50 genes in congenital cataract have been reported with various modes of inheritance. Among them, HSF4 mutations have been reported in autosomal dominant, autosomal recessive and age-related forms of cataract. The inheritance patterns of these mutations depend on their mutational positions in HSF4: autosomal dominant or recessive mutations are respectively found either in a DNA-binding domain or in (or downstream of) hydrophobic repeats. Here we report a novel homozygous HSF4 mutation (c.521T>C, p.Leu174Pro) in two affected sibs of an Iranian consanguineous family using whole exome sequencing. The mutation is predicted as highly pathogenic by in silico analysis (SIFT, Polyphen2 and MutationTaster) and is not found in any of control databases. This mutation is located in a hydrophobic repeat of the HSF4 protein, which is consistent with the mode of inheritance as an autosomal recessive trait. PMID:26490182

  5. A novel recessive GUCY2D mutation causing cone-rod dystrophy and not Leber's congenital amaurosis.

    PubMed

    Ugur Iseri, Sibel A; Durlu, Yusuf K; Tolun, Aslihan

    2010-10-01

    Cone-rod dystrophies are inherited retinal dystrophies that are characterized by progressive degeneration of cones and rods, causing an early decrease in central visual acuity and colour vision defects, followed by loss of peripheral vision in adolescence or early adult life. Both genetic and clinical heterogeneity are well known. In a family with autosomal recessive cone-rod dystrophy, genetic analyses comprising genome scan with microsatellite markers, fine mapping and candidate gene approach resulted in the identification of a homozygous missense GUCY2D mutation. This is the first GUCY2D mutation associated with autosomal recessive cone-rod dystrophy rather than Leber's congenital amaurosis (LCA), a severe disease leading to childhood blindness. This study hence establishes GUCY2D, which is a common cause for both recessive LCA and dominant cone-rod dystrophy, as a good candidate for autosomal recessive cone-rod dystrophy. PMID:20517349

  6. Recessive Mutations in KCNJ13, Encoding an Inwardly Rectifying Potassium Channel Subunit, Cause Leber Congenital Amaurosis

    PubMed Central

    Sergouniotis, Panagiotis I.; Davidson, Alice E.; Mackay, Donna S.; Li, Zheng; Yang, Xu; Plagnol, Vincent; Moore, Anthony T.; Webster, Andrew R.

    2011-01-01

    Inherited retinal degenerations, including retinitis pigmentosa (RP) and Leber congenital amaurosis (LCA), comprise a group of disorders showing high genetic and allelic heterogeneity. The determination of a full catalog of genes that can, when mutated, cause human retinal disease is a powerful means to understand the molecular physiology and pathology of the human retina. As more genes are found, remaining ones are likely to be rarer and/or unexpected candidates. Here, we identify a family in which all known RP/LCA-related genes are unlikely to be associated with their disorder. A combination of homozygosity mapping and exome sequencing identifies a homozygous nonsense mutation, c.496C>T (p.Arg166X), in a gene, KCNJ13, encoding a potassium channel subunit Kir7.1. A screen of a further 333 unrelated individuals with recessive retinal degeneration identified an additional proband, homozygous for a missense mutation, c.722T>C (p.Leu241Pro), in the same gene. The three affected members of the two families have been diagnosed with LCA. All have a distinct and unusual retinal appearance and a similar early onset of visual loss, suggesting both impaired retinal development and progressive retinal degeneration, involving both rod and cone pathways. Examination of heterozygotes revealed no ocular disease. This finding implicates Kir7.1 as having an important role in human retinal development and maintenance. This disorder adds to a small diverse group of diseases consequent upon loss or reduced function of inwardly rectifying potassium channels affecting various organs. The distinct retinal phenotype that results from biallelic mutations in KCNJ13 should facilitate the molecular diagnosis in further families. PMID:21763485

  7. Icebox, a recessive X-linked mutation in Drosophila causing low sexual receptivity.

    PubMed

    Kerr, C; Ringo, J; Dowse, H; Johnson, E

    1997-11-01

    The X-linked recessive mutation icebox (ibx; 1-23, 7F1) of Drosophila melanogaster lowers the sexual receptivity of females. The probability of mating with mature wild-type males is reduced in ibx homozygotes, and the frequency of rejection behavior (rate per minute) towards courting males is increased. ibx fails to complement In(1)RA35, which is a lethal allele of Neuroglian (Nrg, which encodes a transmembrane protein found in embryonic tissues including the nervous system) due to a breakpoint in that gene; however, both l(1)B4 and l(1)VA142, other lethal mutations of Nrg, do complement ibx. 12-h ibx embryos exhibit a normal pattern of staining for the Neuroglian-specific antibody, Mab BP104. Males and females mutant for ibx have normal egg-to-adult survival and appear normal in several "general" behavioral traits including olfaction, phototaxis, locomotor activity, and heartbeat. ibx males court normally, and are successful in mating. These characteristics suggest that ibx does not cause sensory or motor defects. Ovarian growth and sperm storage are wild-type in ibx/ibx females. Treatment with the JH analog methoprene increases the receptivity of ibx/ibx females.

  8. A Founder Mutation in VPS11 Causes an Autosomal Recessive Leukoencephalopathy Linked to Autophagic Defects

    PubMed Central

    Schaffner, Adam; Fedick, Anastasia; Kaye, Lauren E.; Liao, Jun; Yachelevich, Naomi; Chu, Mary-Lynn; Boles, Richard G.; Moran, Ellen; Tokita, Mari; Gorman, Elizabeth; Zhang, Wei; Xia, Fan; Leduc, Magalie; Yang, Yaping; Eng, Christine; Wong, Lee-Jun; Schiffmann, Raphael; Diaz, George A.; Kornreich, Ruth; Thummel, Ryan; Wasserstein, Melissa; Yue, Zhenyu; Edelmann, Lisa

    2016-01-01

    Genetic leukoencephalopathies (gLEs) are a group of heterogeneous disorders with white matter abnormalities affecting the central nervous system (CNS). The causative mutation in ~50% of gLEs is unknown. Using whole exome sequencing (WES), we identified homozygosity for a missense variant, VPS11: c.2536T>G (p.C846G), as the genetic cause of a leukoencephalopathy syndrome in five individuals from three unrelated Ashkenazi Jewish (AJ) families. All five patients exhibited highly concordant disease progression characterized by infantile onset leukoencephalopathy with brain white matter abnormalities, severe motor impairment, cortical blindness, intellectual disability, and seizures. The carrier frequency of the VPS11: c.2536T>G variant is 1:250 in the AJ population (n = 2,026). VPS11 protein is a core component of HOPS (homotypic fusion and protein sorting) and CORVET (class C core vacuole/endosome tethering) protein complexes involved in membrane trafficking and fusion of the lysosomes and endosomes. The cysteine 846 resides in an evolutionarily conserved cysteine-rich RING-H2 domain in carboxyl terminal regions of VPS11 proteins. Our data shows that the C846G mutation causes aberrant ubiquitination and accelerated turnover of VPS11 protein as well as compromised VPS11-VPS18 complex assembly, suggesting a loss of function in the mutant protein. Reduced VPS11 expression leads to an impaired autophagic activity in human cells. Importantly, zebrafish harboring a vps11 mutation with truncated RING-H2 domain demonstrated a significant reduction in CNS myelination following extensive neuronal death in the hindbrain and midbrain. Thus, our study reveals a defect in VPS11 as the underlying etiology for an autosomal recessive leukoencephalopathy disorder associated with a dysfunctional autophagy-lysosome trafficking pathway. PMID:27120463

  9. A Founder Mutation in VPS11 Causes an Autosomal Recessive Leukoencephalopathy Linked to Autophagic Defects.

    PubMed

    Zhang, Jinglan; Lachance, Véronik; Schaffner, Adam; Li, Xianting; Fedick, Anastasia; Kaye, Lauren E; Liao, Jun; Rosenfeld, Jill; Yachelevich, Naomi; Chu, Mary-Lynn; Mitchell, Wendy G; Boles, Richard G; Moran, Ellen; Tokita, Mari; Gorman, Elizabeth; Bagley, Kaytee; Zhang, Wei; Xia, Fan; Leduc, Magalie; Yang, Yaping; Eng, Christine; Wong, Lee-Jun; Schiffmann, Raphael; Diaz, George A; Kornreich, Ruth; Thummel, Ryan; Wasserstein, Melissa; Yue, Zhenyu; Edelmann, Lisa

    2016-04-01

    Genetic leukoencephalopathies (gLEs) are a group of heterogeneous disorders with white matter abnormalities affecting the central nervous system (CNS). The causative mutation in ~50% of gLEs is unknown. Using whole exome sequencing (WES), we identified homozygosity for a missense variant, VPS11: c.2536T>G (p.C846G), as the genetic cause of a leukoencephalopathy syndrome in five individuals from three unrelated Ashkenazi Jewish (AJ) families. All five patients exhibited highly concordant disease progression characterized by infantile onset leukoencephalopathy with brain white matter abnormalities, severe motor impairment, cortical blindness, intellectual disability, and seizures. The carrier frequency of the VPS11: c.2536T>G variant is 1:250 in the AJ population (n = 2,026). VPS11 protein is a core component of HOPS (homotypic fusion and protein sorting) and CORVET (class C core vacuole/endosome tethering) protein complexes involved in membrane trafficking and fusion of the lysosomes and endosomes. The cysteine 846 resides in an evolutionarily conserved cysteine-rich RING-H2 domain in carboxyl terminal regions of VPS11 proteins. Our data shows that the C846G mutation causes aberrant ubiquitination and accelerated turnover of VPS11 protein as well as compromised VPS11-VPS18 complex assembly, suggesting a loss of function in the mutant protein. Reduced VPS11 expression leads to an impaired autophagic activity in human cells. Importantly, zebrafish harboring a vps11 mutation with truncated RING-H2 domain demonstrated a significant reduction in CNS myelination following extensive neuronal death in the hindbrain and midbrain. Thus, our study reveals a defect in VPS11 as the underlying etiology for an autosomal recessive leukoencephalopathy disorder associated with a dysfunctional autophagy-lysosome trafficking pathway. PMID:27120463

  10. Mutations in phospholipase DDHD2 cause autosomal recessive hereditary spastic paraplegia (SPG54).

    PubMed

    Gonzalez, Michael; Nampoothiri, Sheela; Kornblum, Cornelia; Oteyza, Andrés Caballero; Walter, Jochen; Konidari, Ioanna; Hulme, William; Speziani, Fiorella; Schöls, Ludger; Züchner, Stephan; Schüle, Rebecca

    2013-11-01

    Hereditary spastic paraplegias (HSP) are a genetically heterogeneous group of disorders characterized by a distal axonopathy of the corticospinal tract motor neurons leading to progressive lower limb spasticity and weakness. Intracellular membrane trafficking, mitochondrial dysfunction and myelin formation are key functions involved in HSP pathogenesis. Only recently defects in metabolism of complex lipids have been implicated in a number of HSP subtypes. Mutations in the 23 known autosomal recessive HSP genes explain less than half of autosomal recessive HSP cases. To identify novel autosomal recessive HSP disease genes, exome sequencing was performed in 79 index cases with autosomal recessive forms of HSP. Resulting variants were filtered and intersected between families to allow identification of new disease genes. We identified two deleterious mutations in the phospholipase DDHD2 gene in two families with complicated HSP. The phenotype is characterized by early onset of spastic paraplegia, mental retardation, short stature and dysgenesis of the corpus callosum. Phospholipase DDHD2 is involved in intracellular membrane trafficking at the golgi/ endoplasmic reticulum interface and has been shown to possess phospholipase A1 activity in vitro. Discovery of DDHD2 mutations in HSP might therefore provide a link between two key pathogenic themes in HSP: membrane trafficking and lipid metabolism.

  11. Recessive Mutations in the α3 (VI) Collagen Gene COL6A3 Cause Early-Onset Isolated Dystonia

    PubMed Central

    Zech, Michael; Lam, Daniel D.; Francescatto, Ludmila; Schormair, Barbara; Salminen, Aaro V.; Jochim, Angela; Wieland, Thomas; Lichtner, Peter; Peters, Annette; Gieger, Christian; Lochmüller, Hanns; Strom, Tim M.; Haslinger, Bernhard; Katsanis, Nicholas; Winkelmann, Juliane

    2015-01-01

    Isolated dystonia is a disorder characterized by involuntary twisting postures arising from sustained muscle contractions. Although autosomal-dominant mutations in TOR1A, THAP1, and GNAL have been found in some cases, the molecular mechanisms underlying isolated dystonia are largely unknown. In addition, although emphasis has been placed on dominant isolated dystonia, the disorder is also transmitted as a recessive trait, for which no mutations have been defined. Using whole-exome sequencing in a recessive isolated dystonia-affected kindred, we identified disease-segregating compound heterozygous mutations in COL6A3, a collagen VI gene associated previously with muscular dystrophy. Genetic screening of a further 367 isolated dystonia subjects revealed two additional recessive pedigrees harboring compound heterozygous mutations in COL6A3. Strikingly, all affected individuals had at least one pathogenic allele in exon 41, including an exon-skipping mutation that induced an in-frame deletion. We tested the hypothesis that disruption of this exon is pathognomonic for isolated dystonia by inducing a series of in-frame deletions in zebrafish embryos. Consistent with our human genetics data, suppression of the exon 41 ortholog caused deficits in axonal outgrowth, whereas suppression of other exons phenocopied collagen deposition mutants. All recessive mutation carriers demonstrated early-onset segmental isolated dystonia without muscular disease. Finally, we show that Col6a3 is expressed in neurons, with relevant mRNA levels detectable throughout the adult mouse brain. Taken together, our data indicate that loss-of-function mutations affecting a specific region of COL6A3 cause recessive isolated dystonia with underlying neurodevelopmental deficits and highlight the brain extracellular matrix as a contributor to dystonia pathogenesis. PMID:26004199

  12. UBA5 Mutations Cause a New Form of Autosomal Recessive Cerebellar Ataxia

    PubMed Central

    Yu, Li; Zhang, Gehan; Li, Jia; Lin, Yunting; Guo, Jifeng; Wang, Junling; Shen, Lu; Jiang, Hong; Wang, Guanghui; Tang, Beisha

    2016-01-01

    Autosomal recessive cerebellar ataxia (ARCA) comprises a large and heterogeneous group of neurodegenerative disorders. For many affected patients, the genetic cause remains undetermined. Through whole-exome sequencing, we identified compound heterozygous mutations in ubiquitin-like modifier activating enzyme 5 gene (UBA5) in two Chinese siblings presenting with ARCA. Moreover, copy number variations in UBA5 or ubiquitin-fold modifier 1 gene (UFM1) were documented with the phenotypes of global developmental delays and gait disturbances in the ClinVar database. UBA5 encodes UBA5, the ubiquitin-activating enzyme of UFM1. However, a crucial role for UBA5 in human neurological disease remains to be reported. Our molecular study of UBA5-R246X revealed a dramatically decreased half-life and loss of UFM1 activation due to the absence of the catalytic cysteine Cys250. UBA5-K310E maintained its interaction with UFM1, although with less stability, which may affect the ability of this UBA5 mutant to activate UFM1. Drosophila modeling revealed that UBA5 knockdown induced locomotive defects and a shortened lifespan accompanied by aberrant neuromuscular junctions (NMJs). Strikingly, we found that UFM1 and E2 cofactor knockdown induced markedly similar phenotypes. Wild-type UBA5, but not mutant UBA5, significantly restored neural lesions caused by the absence of UBA5. The finding of a UBA5 mutation in cerebellar ataxia suggests that impairment of the UFM1 pathway may contribute to the neurological phenotypes of ARCA. PMID:26872069

  13. Recessive Mutations in RTN4IP1 Cause Isolated and Syndromic Optic Neuropathies

    PubMed Central

    Angebault, Claire; Guichet, Pierre-Olivier; Talmat-Amar, Yasmina; Charif, Majida; Gerber, Sylvie; Fares-Taie, Lucas; Gueguen, Naig; Halloy, François; Moore, David; Amati-Bonneau, Patrizia; Manes, Gael; Hebrard, Maxime; Bocquet, Béatrice; Quiles, Mélanie; Piro-Mégy, Camille; Teigell, Marisa; Delettre, Cécile; Rossel, Mireille; Meunier, Isabelle; Preising, Markus; Lorenz, Birgit; Carelli, Valerio; Chinnery, Patrick F.; Yu-Wai-Man, Patrick; Kaplan, Josseline; Roubertie, Agathe; Barakat, Abdelhamid; Bonneau, Dominique; Reynier, Pascal; Rozet, Jean-Michel; Bomont, Pascale; Hamel, Christian P.; Lenaers, Guy

    2015-01-01

    Autosomal-recessive optic neuropathies are rare blinding conditions related to retinal ganglion cell (RGC) and optic-nerve degeneration, for which only mutations in TMEM126A and ACO2 are known. In four families with early-onset recessive optic neuropathy, we identified mutations in RTN4IP1, which encodes a mitochondrial ubiquinol oxydo-reductase. RTN4IP1 is a partner of RTN4 (also known as NOGO), and its ortholog Rad8 in C. elegans is involved in UV light response. Analysis of fibroblasts from affected individuals with a RTN4IP1 mutation showed loss of the altered protein, a deficit of mitochondrial respiratory complex I and IV activities, and increased susceptibility to UV light. Silencing of RTN4IP1 altered the number and morphogenesis of mouse RGC dendrites in vitro and the eye size, neuro-retinal development, and swimming behavior in zebrafish in vivo. Altogether, these data point to a pathophysiological mechanism responsible for RGC early degeneration and optic neuropathy and linking RTN4IP1 functions to mitochondrial physiology, response to UV light, and dendrite growth during eye maturation. PMID:26593267

  14. Recessive mutations in POLR1C cause a leukodystrophy by impairing biogenesis of RNA polymerase III

    PubMed Central

    Thiffault, Isabelle; Wolf, Nicole I.; Forget, Diane; Guerrero, Kether; Tran, Luan T.; Choquet, Karine; Lavallée-Adam, Mathieu; Poitras, Christian; Brais, Bernard; Yoon, Grace; Sztriha, Laszlo; Webster, Richard I.; Timmann, Dagmar; van de Warrenburg, Bart P.; Seeger, Jürgen; Zimmermann, Alíz; Máté, Adrienn; Goizet, Cyril; Fung, Eva; van der Knaap, Marjo S.; Fribourg, Sébastien; Vanderver, Adeline; Simons, Cas; Taft, Ryan J.; Yates III, John R.; Coulombe, Benoit; Bernard, Geneviève

    2015-01-01

    A small proportion of 4H (Hypomyelination, Hypodontia and Hypogonadotropic Hypogonadism) or RNA polymerase III (POLR3)-related leukodystrophy cases are negative for mutations in the previously identified causative genes POLR3A and POLR3B. Here we report eight of these cases carrying recessive mutations in POLR1C, a gene encoding a shared POLR1 and POLR3 subunit, also mutated in some Treacher Collins syndrome (TCS) cases. Using shotgun proteomics and ChIP sequencing, we demonstrate that leukodystrophy-causative mutations, but not TCS mutations, in POLR1C impair assembly and nuclear import of POLR3, but not POLR1, leading to decreased binding to POLR3 target genes. This study is the first to show that distinct mutations in a gene coding for a shared subunit of two RNA polymerases lead to selective modification of the enzymes' availability leading to two different clinical conditions and to shed some light on the pathophysiological mechanism of one of the most common hypomyelinating leukodystrophies, POLR3-related leukodystrophy. PMID:26151409

  15. Pathognomonic oral profile of Enamel Renal Syndrome (ERS) caused by recessive FAM20A mutations

    PubMed Central

    2014-01-01

    Amelogenesis imperfecta (AI) is a genetically and clinically heterogeneous group of inherited dental enamel defects. Commonly described as an isolated trait, it may be observed concomitantly with other orodental and/or systemic features such as nephrocalcinosis in Enamel Renal Syndrome (ERS, MIM#204690), or gingival hyperplasia in Amelogenesis Imperfecta and Gingival Fibromatosis Syndrome (AIGFS, MIM#614253). Patients affected by ERS/AIGFS present a distinctive orodental phenotype consisting of generalized hypoplastic AI affecting both the primary and permanent dentition, delayed tooth eruption, pulp stones, hyperplastic dental follicles, and gingival hyperplasia with variable severity and calcified nodules. Renal exam reveals a nephrocalcinosis which is asymptomatic in children affected by ERS. FAM20A recessive mutations are responsible for both syndromes. We suggest that AIGFS and ERS are in fact descriptions of the same syndrome, but that the kidney phenotype has not always been investigated fully in AIGFS. The aim of this review is to highlight the distinctive and specific orodental features of patients with recessive mutations in FAM20A. We propose ERS to be the preferred term for all the phenotypes arising from recessive FAM20A mutations. A differential diagnosis has to be made with other forms of AI, isolated or syndromic, where only a subset of the clinical signs may be shared. When ERS is suspected, the patient should be assessed by a dentist, nephrologist and clinical geneticist. Confirmed cases require long-term follow-up. Management of the orodental aspects can be extremely challenging and requires the input of multi-disciplinary specialized dental team, especially when there are multiple unerupted teeth. PMID:24927635

  16. A nonsense mutation in PDE6H causes autosomal-recessive incomplete achromatopsia.

    PubMed

    Kohl, Susanne; Coppieters, Frauke; Meire, Françoise; Schaich, Simone; Roosing, Susanne; Brennenstuhl, Christina; Bolz, Sylvia; van Genderen, Maria M; Riemslag, Frans C C; Lukowski, Robert; den Hollander, Anneke I; Cremers, Frans P M; De Baere, Elfride; Hoyng, Carel B; Wissinger, Bernd

    2012-09-01

    Achromatopsia (ACHM) is an autosomal-recessive retinal dystrophy characterized by color blindness, photophobia, nystagmus, and severely reduced visual acuity. Its prevalence has been estimated to about 1 in 30,000 individuals. Four genes, GNAT2, PDE6C, CNGA3, and CNGB3, have been implicated in ACHM, and all encode functional components of the phototransduction cascade in cone photoreceptors. Applying a functional-candidate-gene approach that focused on screening additional genes involved in this process in a cohort of 611 index cases with ACHM or other cone photoreceptor disorders, we detected a homozygous single base change (c.35C>G) resulting in a nonsense mutation (p.Ser12(∗)) in PDE6H, encoding the inhibitory γ subunit of the cone photoreceptor cyclic guanosine monophosphate phosphodiesterase. The c.35C>G mutation was present in three individuals from two independent families with a clinical diagnosis of incomplete ACHM and preserved short-wavelength-sensitive cone function. Moreover, we show through immunohistochemical colocalization studies in mouse retina that Pde6h is evenly present in all retinal cone photoreceptors, a fact that had been under debate in the past. These findings add PDE6H to the set of genes involved in autosomal-recessive cone disorders and demonstrate the importance of the inhibitory γ subunit in cone phototransduction. PMID:22901948

  17. Mutations in SNX14 Cause a Distinctive Autosomal-Recessive Cerebellar Ataxia and Intellectual Disability Syndrome

    PubMed Central

    Thomas, Anna C.; Williams, Hywel; Setó-Salvia, Núria; Bacchelli, Chiara; Jenkins, Dagan; O’Sullivan, Mary; Mengrelis, Konstantinos; Ishida, Miho; Ocaka, Louise; Chanudet, Estelle; James, Chela; Lescai, Francesco; Anderson, Glenn; Morrogh, Deborah; Ryten, Mina; Duncan, Andrew J.; Pai, Yun Jin; Saraiva, Jorge M.; Ramos, Fabiana; Farren, Bernadette; Saunders, Dawn; Vernay, Bertrand; Gissen, Paul; Straatmaan-Iwanowska, Anna; Baas, Frank; Wood, Nicholas W.; Hersheson, Joshua; Houlden, Henry; Hurst, Jane; Scott, Richard; Bitner-Glindzicz, Maria; Moore, Gudrun E.; Sousa, Sérgio B.; Stanier, Philip

    2014-01-01

    Intellectual disability and cerebellar atrophy occur together in a large number of genetic conditions and are frequently associated with microcephaly and/or epilepsy. Here we report the identification of causal mutations in Sorting Nexin 14 (SNX14) found in seven affected individuals from three unrelated consanguineous families who presented with recessively inherited moderate-severe intellectual disability, cerebellar ataxia, early-onset cerebellar atrophy, sensorineural hearing loss, and the distinctive association of progressively coarsening facial features, relative macrocephaly, and the absence of seizures. We used homozygosity mapping and whole-exome sequencing to identify a homozygous nonsense mutation and an in-frame multiexon deletion in two families. A homozygous splice site mutation was identified by Sanger sequencing of SNX14 in a third family, selected purely by phenotypic similarity. This discovery confirms that these characteristic features represent a distinct and recognizable syndrome. SNX14 encodes a cellular protein containing Phox (PX) and regulator of G protein signaling (RGS) domains. Weighted gene coexpression network analysis predicts that SNX14 is highly coexpressed with genes involved in cellular protein metabolism and vesicle-mediated transport. All three mutations either directly affected the PX domain or diminished SNX14 levels, implicating a loss of normal cellular function. This manifested as increased cytoplasmic vacuolation as observed in cultured fibroblasts. Our findings indicate an essential role for SNX14 in neural development and function, particularly in development and maturation of the cerebellum. PMID:25439728

  18. Allelic background of LEPRE1 mutations that cause recessive forms of osteogenesis imperfecta in different populations

    PubMed Central

    Pepin, Melanie G; Schwarze, Ulrike; Singh, Virendra; Romana, Marc; Jones-LeCointe, Altheia; Byers, Peter H

    2013-01-01

    Biallelic mutations in LEPRE1 result in recessively inherited forms of osteogenesis imperfecta (OI) that are often lethal in the perinatal period. A mutation (c.1080+1G>T, IVS5+1G>T) in African Americans has a carrier frequency of about 1/240. The mutant allele originated in West Africa in tribes of Ghana and Nigeria where the carrier frequencies are 2% and 5%. By examining 200 samples from an African-derived population in Tobago and reviewing hospital neonatal death records, we determined that the carrier frequency of c.1080+1G>T was about one in 200 and did not contribute to the neonatal deaths recorded over a 3-year period of time in Trinidad. In the course of sequence analysis, we found surprisingly high LEPRE1 allelic diversity in the Tobago DNA samples in which there were 11 alleles distinguished by a single basepair variant in or near exon 5. All the alleles found in the Tobago population that were within the sequence analysis region were found in the African American population in the Exome Variant Project. This diversity appeared to reflect the geographic origin of the original population in Tobago. In 44 individuals with biallelic LEPRE1 mutations identified by clinical diagnostic testing, we found the sequence alterations occurred on seven of the 11 variant alleles. All but one of the mutations identified resulted in mRNA or protein instability for the majority of the transcripts from the altered allele. These findings suggest that the milder end of the clinical spectrum could be due to as yet unidentified missense mutations in LEPRE1. PMID:24498616

  19. Recessively inherited multiple epiphyseal dysplasia with normal stature, club foot, and double layered patella caused by a DTDST mutation

    PubMed Central

    Superti-Furga, A.; Neumann, L.; Riebel, T.; Eich, G.; Steinmann, B.; Spranger, J.; Kunze, J.

    1999-01-01

    We have observed over 25 different mutations in the diastrophic dysplasia sulphate transporter gene (DTDST) in association with the recessive disorders achondrogenesis 1B, atelosteogenesis 2, and diastrophic dysplasia. The c862t (R279W) transition is the most common mutation in non-Finnish patients, but in these disorders it is usually combined with other DTDST mutations. We had not seen a case of homozygosity for c862t (R279W) until we analysed DNA from a 36 year old male with tall-normal stature (180 cm) who asked for genetic counselling for suspected multiple epiphyseal dysplasia. He was treated for club foot and hip dysplasia at birth. Skeletal changes consistent with multiple epiphyseal dysplasia, with the peculiar finding of a double layered patella, were recognised during childhood. Cleft palate, swelling of the ear pinna, and hitch hiker thumb were absent. He was found to be homozygous, and both healthy parents heterozygous, for the R279W mutation in DTDST, and his fibroblasts showed a sulphate incorporation defect typical of DTDST disorders. Counselling was given for a recessive disorder, thereby considerably reducing the probability of affected offspring.
  Multiple epiphyseal dysplasia is more frequently caused by dominant mutations in the COMP (EDM1, McKusick 132400) and COL9A2 genes (EDM2, McKusick 600204). A few other patients and families with features similar to our proband have been described previously and considered to have autosomal recessive MED (EDM4, McKusick 226900). This observation confirms the existence of this entity and assigns it to the phenotypic spectrum associated with mutations at the DTDST locus.


Keywords: multiple epiphyseal dysplasia; DTDST; double layered patella PMID:10465113

  20. Recessively inherited multiple epiphyseal dysplasia with normal stature, club foot, and double layered patella caused by a DTDST mutation.

    PubMed

    Superti-Furga, A; Neumann, L; Riebel, T; Eich, G; Steinmann, B; Spranger, J; Kunze, J

    1999-08-01

    We have observed over 25 different mutations in the diastrophic dysplasia sulphate transporter gene (DTDST) in association with the recessive disorders achondrogenesis 1B, atelosteogenesis 2, and diastrophic dysplasia. The c862t (R279W) transition is the most common mutation in non-Finnish patients, but in these disorders it is usually combined with other DTDST mutations. We had not seen a case of homozygosity for c862t (R279W) until we analysed DNA from a 36 year old male with tall-normal stature (180 cm) who asked for genetic counselling for suspected multiple epiphyseal dysplasia. He was treated for club foot and hip dysplasia at birth. Skeletal changes consistent with multiple epiphyseal dysplasia, with the peculiar finding of a double layered patella, were recognised during childhood. Cleft palate, swelling of the ear pinna, and hitch hiker thumb were absent. He was found to be homozygous, and both healthy parents heterozygous, for the R279W mutation in DTDST, and his fibroblasts showed a sulphate incorporation defect typical of DTDST disorders. Counselling was given for a recessive disorder, thereby considerably reducing the probability of affected offspring. Multiple epiphyseal dysplasia is more frequently caused by dominant mutations in the COMP (EDM1, McKusick 132400) and COL9A2 genes (EDM2, McKusick 600204). A few other patients and families with features similar to our proband have been described previously and considered to have autosomal recessive MED (EDM4, McKusick 226900). This observation confirms the existence of this entity and assigns it to the phenotypic spectrum associated with mutations at the DTDST locus. PMID:10465113

  1. ITGB6 loss-of-function mutations cause autosomal recessive amelogenesis imperfecta.

    PubMed

    Wang, Shih-Kai; Choi, Murim; Richardson, Amelia S; Reid, Bryan M; Lin, Brent P; Wang, Susan J; Kim, Jung-Wook; Simmer, James P; Hu, Jan C-C

    2014-04-15

    Integrins are cell-surface adhesion receptors that bind to extracellular matrices (ECM) and mediate cell-ECM interactions. Some integrins are known to play critical roles in dental enamel formation. We recruited two Hispanic families with generalized hypoplastic amelogenesis imperfecta (AI). Analysis of whole-exome sequences identified three integrin beta 6 (ITGB6) mutations responsible for their enamel malformations. The female proband of Family 1 was a compound heterozygote with an ITGB6 transition mutation in Exon 4 (g.4545G > A c.427G > A p.Ala143Thr) and an ITGB6 transversion mutation in Exon 6 (g.27415T > A c.825T > A p.His275Gln). The male proband of Family 2 was homozygous for an ITGB6 transition mutation in Exon 11 (g.73664C > T c.1846C > T p.Arg616*) and hemizygous for a transition mutation in Exon 6 of Nance-Horan Syndrome (NHS Xp22.13; g.355444T > C c.1697T > C p.Met566Thr). These are the first disease-causing ITGB6 mutations to be reported. Immunohistochemistry of mouse mandibular incisors localized ITGB6 to the distal membrane of differentiating ameloblasts and pre-ameloblasts, and then ITGB6 appeared to be internalized by secretory stage ameloblasts. ITGB6 expression was strongest in the maturation stage and its localization was associated with ameloblast modulation. Our findings demonstrate that early and late amelogenesis depend upon cell-matrix interactions. Our approach (from knockout mouse phenotype to human disease) demonstrates the power of mouse reverse genetics in mutational analysis of human genetic disorders and attests to the need for a careful dental phenotyping in large-scale knockout mouse projects.

  2. A frameshift mutation in GRXCR2 causes recessively inherited hearing loss.

    PubMed

    Imtiaz, Ayesha; Kohrman, David C; Naz, Sadaf

    2014-05-01

    More than 360 million humans are affected with some degree of hearing loss, either early or later in life. A genetic cause for the disorder is present in a majority of the cases. We mapped a locus (DFNB101) for hearing loss in humans to chromosome 5q in a consanguineous Pakistani family. Exome sequencing revealed an insertion mutation in GRXCR2 as the cause of moderate-to-severe and likely progressive hearing loss in the affected individuals of the family. The frameshift mutation is predicted to affect a conserved, cysteine-rich region of GRXCR2, and to result in an abnormal extension of the C-terminus. Functional studies by cell transfections demonstrated that the mutant protein is unstable and mislocalized relative to wild-type GRXCR2, consistent with a loss-of-function mutation. Targeted disruption of Grxcr2 is concurrently reported to cause hearing loss in mice. The structural abnormalities in this animal model suggest a role for GRXCR2 in the development of stereocilia bundles, specialized structures on the apical surface of sensory cells in the cochlea that are critical for sound detection. Our results indicate that GRXCR2 should be considered in differential genetic diagnosis for individuals with early onset, moderate-to-severe and progressive hearing loss.

  3. Recessive mutations in PCBD1 cause a new type of early-onset diabetes.

    PubMed

    Simaite, Deimante; Kofent, Julia; Gong, Maolian; Rüschendorf, Franz; Jia, Shiqi; Arn, Pamela; Bentler, Kristi; Ellaway, Carolyn; Kühnen, Peter; Hoffmann, Georg F; Blau, Nenad; Spagnoli, Francesca M; Hübner, Norbert; Raile, Klemens

    2014-10-01

    Mutations in several genes cause nonautoimmune diabetes, but numerous patients still have unclear genetic defects, hampering our understanding of the development of the disease and preventing pathogenesis-oriented treatment. We used whole-genome sequencing with linkage analysis to study a consanguineous family with early-onset antibody-negative diabetes and identified a novel deletion in PCBD1 (pterin-4 α-carbinolamine dehydratase/dimerization cofactor of hepatocyte nuclear factor 1 α), a gene that was recently proposed as a likely cause of diabetes. A subsequent reevaluation of patients with mild neonatal hyperphenylalaninemia due to mutations in PCBD1 from the BIODEF database identified three additional patients who had developed HNF1A-like diabetes in puberty, indicating early β-cell failure. We found that Pcbd1 is expressed in the developing pancreas of both mouse and Xenopus embryos from early specification onward showing colocalization with insulin. Importantly, a morpholino-mediated knockdown in Xenopus revealed that pcbd1 activity is required for the proper establishment of early pancreatic fate within the endoderm. We provide the first genetic evidence that PCBD1 mutations can cause early-onset nonautoimmune diabetes with features similar to dominantly inherited HNF1A-diabetes. This condition responds to and can be treated with oral drugs instead of insulin, which is important clinical information for these patients. Finally, patients at risk can be detected through a newborn screening for phenylketonuria.

  4. Mutation in the auxiliary calcium-channel subunit CACNA2D4 causes autosomal recessive cone dystrophy.

    PubMed

    Wycisk, Katharina Agnes; Zeitz, Christina; Feil, Silke; Wittmer, Mariana; Forster, Ursula; Neidhardt, John; Wissinger, Bernd; Zrenner, Eberhart; Wilke, Robert; Kohl, Susanne; Berger, Wolfgang

    2006-11-01

    Retinal signal transmission depends on the activity of high voltage-gated l-type calcium channels in photoreceptor ribbon synapses. We recently identified a truncating frameshift mutation in the Cacna2d4 gene in a spontaneous mouse mutant with profound loss of retinal signaling and an abnormal morphology of ribbon synapses in rods and cones. The Cacna2d4 gene encodes an l-type calcium-channel auxiliary subunit of the alpha (2) delta type. Mutations in its human orthologue, CACNA2D4, were not yet known to be associated with a disease. We performed mutation analyses of 34 patients who received an initial diagnosis of night blindness, and, in two affected siblings, we detected a homozygous nucleotide substitution (c.2406C-->A) in CACNA2D4. The mutation introduces a premature stop codon that truncates one-third of the corresponding open reading frame. Both patients share symptoms of slowly progressing cone dystrophy. These findings represent the first report of a mutation in the human CACNA2D4 gene and define a novel gene defect that causes autosomal recessive cone dystrophy.

  5. Autosomal-Recessive Mutations in the tRNA Splicing Endonuclease Subunit TSEN15 Cause Pontocerebellar Hypoplasia and Progressive Microcephaly.

    PubMed

    Breuss, Martin W; Sultan, Tipu; James, Kiely N; Rosti, Rasim O; Scott, Eric; Musaev, Damir; Furia, Bansri; Reis, André; Sticht, Heinrich; Al-Owain, Mohammed; Alkuraya, Fowzan S; Reuter, Miriam S; Abou Jamra, Rami; Trotta, Christopher R; Gleeson, Joseph G

    2016-07-01

    The tRNA splicing endonuclease is a highly evolutionarily conserved protein complex, involved in the cleavage of intron-containing tRNAs. In human it consists of the catalytic subunits TSEN2 and TSEN34, as well as the non-catalytic TSEN54 and TSEN15. Recessive mutations in the corresponding genes of the first three are known to cause pontocerebellar hypoplasia (PCH) types 2A-C, 4, and 5. Here, we report three homozygous TSEN15 variants that cause a milder version of PCH2. The affected individuals showed progressive microcephaly, delayed developmental milestones, intellectual disability, and, in two out of four cases, epilepsy. None, however, displayed the central visual failure seen in PCH case subjects where other subunits of the TSEN are mutated, and only one was affected by the extensive motor defects that are typical in other forms of PCH2. The three amino acid substitutions impacted the protein level of TSEN15 and the stoichiometry of the interacting subunits in different ways, but all resulted in an almost complete loss of in vitro tRNA cleavage activity. Taken together, our results demonstrate that mutations in any known subunit of the TSEN complex can cause PCH and progressive microcephaly, emphasizing the importance of its function during brain development.

  6. Autosomal-Recessive Mutations in the tRNA Splicing Endonuclease Subunit TSEN15 Cause Pontocerebellar Hypoplasia and Progressive Microcephaly.

    PubMed

    Breuss, Martin W; Sultan, Tipu; James, Kiely N; Rosti, Rasim O; Scott, Eric; Musaev, Damir; Furia, Bansri; Reis, André; Sticht, Heinrich; Al-Owain, Mohammed; Alkuraya, Fowzan S; Reuter, Miriam S; Abou Jamra, Rami; Trotta, Christopher R; Gleeson, Joseph G

    2016-07-01

    The tRNA splicing endonuclease is a highly evolutionarily conserved protein complex, involved in the cleavage of intron-containing tRNAs. In human it consists of the catalytic subunits TSEN2 and TSEN34, as well as the non-catalytic TSEN54 and TSEN15. Recessive mutations in the corresponding genes of the first three are known to cause pontocerebellar hypoplasia (PCH) types 2A-C, 4, and 5. Here, we report three homozygous TSEN15 variants that cause a milder version of PCH2. The affected individuals showed progressive microcephaly, delayed developmental milestones, intellectual disability, and, in two out of four cases, epilepsy. None, however, displayed the central visual failure seen in PCH case subjects where other subunits of the TSEN are mutated, and only one was affected by the extensive motor defects that are typical in other forms of PCH2. The three amino acid substitutions impacted the protein level of TSEN15 and the stoichiometry of the interacting subunits in different ways, but all resulted in an almost complete loss of in vitro tRNA cleavage activity. Taken together, our results demonstrate that mutations in any known subunit of the TSEN complex can cause PCH and progressive microcephaly, emphasizing the importance of its function during brain development. PMID:27392077

  7. Mutations in apoptosis-inducing factor cause X-linked recessive auditory neuropathy spectrum disorder

    PubMed Central

    Zong, Liang; Guan, Jing; Ealy, Megan; Zhang, Qiujing; Wang, Dayong; Wang, Hongyang; Zhao, Yali; Shen, Zhirong; Campbell, Colleen A; Wang, Fengchao; Yang, Ju; Sun, Wei; Lan, Lan; Ding, Dalian; Xie, Linyi; Qi, Yue; Lou, Xin; Huang, Xusheng; Shi, Qiang; Chang, Suhua; Xiong, Wenping; Yin, Zifang; Yu, Ning; Zhao, Hui; Wang, Jun; Wang, Jing; Salvi, Richard J; Petit, Christine; Smith, Richard J H; Wang, Qiuju

    2015-01-01

    Background Auditory neuropathy spectrum disorder (ANSD) is a form of hearing loss in which auditory signal transmission from the inner ear to the auditory nerve and brain stem is distorted, giving rise to speech perception difficulties beyond that expected for the observed degree of hearing loss. For many cases of ANSD, the underlying molecular pathology and the site of lesion remain unclear. The X-linked form of the condition, AUNX1, has been mapped to Xq23-q27.3, although the causative gene has yet to be identified. Methods We performed whole-exome sequencing on DNA samples from the AUNX1 family and another small phenotypically similar but unrelated ANSD family. Results We identified two missense mutations in AIFM1 in these families: c.1352G>A (p.R451Q) in the AUNX1 family and c.1030C>T (p.L344F) in the second ANSD family. Mutation screening in a large cohort of 3 additional unrelated families and 93 sporadic cases with ANSD identified 9 more missense mutations in AIFM1. Bioinformatics analysis and expression studies support this gene as being causative of ANSD. Conclusions Variants in AIFM1 gene are a common cause of familial and sporadic ANSD and provide insight into the expanded spectrum of AIFM1-associated diseases. The finding of cochlear nerve hypoplasia in some patients was AIFM1-related ANSD implies that MRI may be of value in localising the site of lesion and suggests that cochlea implantation in these patients may have limited success. PMID:25986071

  8. Mutation of SALL2 causes recessive ocular coloboma in humans and mice

    PubMed Central

    Kelberman, Daniel; Islam, Lily; Lakowski, Jörn; Bacchelli, Chiara; Chanudet, Estelle; Lescai, Francesco; Patel, Aara; Stupka, Elia; Buck, Anja; Wolf, Stephan; Beales, Philip L.; Jacques, Thomas S.; Bitner-Glindzicz, Maria; Liasis, Alki; Lehmann, Ordan J.; Kohlhase, Jürgen; Nischal, Ken K.; Sowden, Jane C.

    2014-01-01

    Ocular coloboma is a congenital defect resulting from failure of normal closure of the optic fissure during embryonic eye development. This birth defect causes childhood blindness worldwide, yet the genetic etiology is poorly understood. Here, we identified a novel homozygous mutation in the SALL2 gene in members of a consanguineous family affected with non-syndromic ocular coloboma variably affecting the iris and retina. This mutation, c.85G>T, introduces a premature termination codon (p.Glu29*) predicted to truncate the SALL2 protein so that it lacks three clusters of zinc-finger motifs that are essential for DNA-binding activity. This discovery identifies SALL2 as the third member of the Drosophila homeotic Spalt-like family of developmental transcription factor genes implicated in human disease. SALL2 is expressed in the developing human retina at the time of, and subsequent to, optic fissure closure. Analysis of Sall2-deficient mouse embryos revealed delayed apposition of the optic fissure margins and the persistence of an anterior retinal coloboma phenotype after birth. Sall2-deficient embryos displayed correct posterior closure toward the optic nerve head, and upon contact of the fissure margins, dissolution of the basal lamina occurred and PAX2, known to be critical for this process, was expressed normally. Anterior closure was disrupted with the fissure margins failing to meet, or in some cases misaligning leading to a retinal lesion. These observations demonstrate, for the first time, a role for SALL2 in eye morphogenesis and that loss of function of the gene causes ocular coloboma in humans and mice. PMID:24412933

  9. Autosomal recessive posterior column ataxia with retinitis pigmentosa caused by novel mutations in the FLVCR1 gene.

    PubMed

    Shaibani, Aziz; Wong, Lee-Jun; Wei Zhang, Victor; Lewis, Richard Alan; Shinawi, Marwan

    2015-01-01

    Posterior column ataxia with retinitis pigmentosa (PCARP) is an autosomal recessive disorder characterized by severe sensory ataxia, muscle weakness and atrophy, and progressive pigmentary retinopathy. Recently, mutations in the FLVCR1 gene were described in four families with this condition. We investigated the molecular basis and studied the phenotype of PCARP in a new family. The proband is a 33-year-old woman presented with sensory polyneuropathy and retinitis pigmentosa (RP). The constellation of clinical findings with normal metabolic and genetic evaluation, including mitochondrial DNA (mtDNA) analysis and normal levels of phytanic acid and vitamin E, prompted us to seek other causes of our patient's condition. Sequencing of FLVCR1 in the proband and targeted mutation testing in her two affected siblings revealed two novel variants, c.1547G > A (p.R516Q) and c.1593+5_+8delGTAA predicted, respectively, to be highly conserved throughout evolution and affecting the normal splicing, therefore, deleterious. This study supports the pathogenic role of FLVCR1 in PCARP and expands the molecular and clinical spectra of PCARP. We show for the first time that nontransmembrane domain (TMD) mutations in the FLVCR1 can cause PCARP, suggesting different mechanisms for pathogenicity. Our clinical data reveal that impaired sensation can be part of the phenotypic spectrum of PCARP. This study along with previously reported cases suggests that targeted sequencing of the FLVCR1 gene should be considered in patients with severe sensory ataxia, RP, and peripheral sensory neuropathy.

  10. Mutations in NALCN cause an autosomal-recessive syndrome with severe hypotonia, speech impairment, and cognitive delay.

    PubMed

    Al-Sayed, Moeenaldeen D; Al-Zaidan, Hamad; Albakheet, Albandary; Hakami, Hana; Kenana, Rosan; Al-Yafee, Yusra; Al-Dosary, Mazhor; Qari, Alya; Al-Sheddi, Tarfa; Al-Muheiza, Muhammed; Al-Qubbaj, Wafa; Lakmache, Yamina; Al-Hindi, Hindi; Ghaziuddin, Muhammad; Colak, Dilek; Kaya, Namik

    2013-10-01

    Sodium leak channel, nonselective (NALCN) is a voltage-independent and cation-nonselective channel that is mainly responsible for the leaky sodium transport across neuronal membranes and controls neuronal excitability. Although NALCN variants have been conflictingly reported to be in linkage disequilibrium with schizophrenia and bipolar disorder, to our knowledge, no mutations have been reported to date for any inherited disorders. Using linkage, SNP-based homozygosity mapping, targeted sequencing, and confirmatory exome sequencing, we identified two mutations, one missense and one nonsense, in NALCN in two unrelated families. The mutations cause an autosomal-recessive syndrome characterized by subtle facial dysmorphism, variable degrees of hypotonia, speech impairment, chronic constipation, and intellectual disability. Furthermore, one of the families pursued preimplantation genetic diagnosis on the basis of the results from this study, and the mother recently delivered healthy twins, a boy and a girl, with no symptoms of hypotonia, which was present in all the affected children at birth. Hence, the two families we describe here represent instances of loss of function in human NALCN. PMID:24075186

  11. Evidence for autosomal recessive inheritance in SPG3A caused by homozygosity for a novel ATL1 missense mutation

    PubMed Central

    Khan, Tahir Naeem; Klar, Joakim; Tariq, Muhammad; Anjum Baig, Shehla; Malik, Naveed Altaf; Yousaf, Raja; Baig, Shahid Mahmood; Dahl, Niklas

    2014-01-01

    Hereditary spastic paraplegias (HSPs) comprise a heterogeneous group of disorders characterized by progressive spasticity and weakness of the lower limbs. Autosomal dominant and ‘pure' forms of HSP account for ∼80% of cases in Western societies of whom 10% carry atlastin-1 (ATL1) gene mutations. We report on a large consanguineous family segregating six members with early onset HSP. The pedigree was compatible with both autosomal dominant and autosomal recessive inheritance. Whole-exome sequencing and segregation analysis revealed a homozygous novel missense variant c.353G>A, p.(Arg118Gln) in ATL1 in all six affected family members. Seven heterozygous carriers, five females and two males, showed no clinical signs of HSP with the exception of sub-clinically reduced vibration sensation in one adult female. Our combined findings show that homozygosity for the ATL1 missense variant remains the only plausible cause of HSP, whereas heterozygous carriers are asymptomatic. This apparent autosomal recessive inheritance adds to the clinical complexity of spastic paraplegia 3A and calls for caution using directed genetic screening in HSP. PMID:24473461

  12. Homozygosity mapping reveals null mutations in FAM161A as a cause of autosomal-recessive retinitis pigmentosa.

    PubMed

    Bandah-Rozenfeld, Dikla; Mizrahi-Meissonnier, Liliana; Farhy, Chen; Obolensky, Alexey; Chowers, Itay; Pe'er, Jacob; Merin, Saul; Ben-Yosef, Tamar; Ashery-Padan, Ruth; Banin, Eyal; Sharon, Dror

    2010-09-10

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal degenerations caused by mutations in at least 45 genes. Using homozygosity mapping, we identified a ∼4 Mb homozygous region on chromosome 2p15 in patients with autosomal-recessive RP (arRP). This region partially overlaps with RP28, a previously identified arRP locus. Sequence analysis of 12 candidate genes revealed three null mutations in FAM161A in 20 families. RT-PCR analysis in 21 human tissues revealed high levels of FAM161A expression in the retina and lower levels in the brain and testis. In the human retina, we identified two alternatively spliced transcripts with an intact open reading frame, the major one lacking a highly conserved exon. During mouse embryonic development, low levels of Fam161a transcripts were detected throughout the optic cup. After birth, Fam161a expression was elevated and confined to the photoreceptor layer. FAM161A encodes a protein of unknown function that is moderately conserved in mammals. Clinical manifestations of patients with FAM161A mutations varied but were largely within the spectrum associated with arRP. On funduscopy, pallor of the optic discs and attenuation of blood vessels were common, but bone-spicule-like pigmentation was often mild or lacking. Most patients had nonrecordable electroretinographic responses and constriction of visual fields upon diagnosis. Our data suggest a pivotal role for FAM161A in photoreceptors and reveal that FAM161A loss-of-function mutations are a major cause of arRP, accounting for ∼12% of arRP families in our cohort of patients from Israel and the Palestinian territories.

  13. G418-mediated ribosomal read-through of a nonsense mutation causing autosomal recessive proximal renal tubular acidosis

    PubMed Central

    Azimov, Rustam; Abuladze, Natalia; Sassani, Pakan; Newman, Debra; Kao, Liyo; Liu, Weixin; Orozco, Nicholas; Ruchala, Piotr; Pushkin, Alexander; Kurtz, Ira

    2008-01-01

    Autosomal recessive proximal renal tubular acidosis is caused by mutations in the SLC4A4 gene encoding the electrogenic sodium bicarbonate cotransporter NBCe1-A. The mutations that have been characterized thus far result in premature truncation, mistargeting, or decreased function of the cotransporter. Despite bicarbonate treatment to correct the metabolic acidosis, extrarenal manifestations persist, including glaucoma, cataracts, corneal opacification, and mental retardation. Currently, there are no known therapeutic approaches that can specifically target mutant NBCe1-A proteins. In the present study, we tested the hypothesis that the NBCe1-A-Q29X mutation can be rescued in vitro by treatment with aminoglycoside antibiotics, which are known for their ability to suppress premature stop codons. As a model system, we cloned the NBCe1-A-Q29X mutant into a vector lacking an aminoglycoside resistance gene and transfected the mutant cotransporter in HEK293-H cells. Cells transfected with the NBCe1-A-Q29X mutant failed to express the cotransporter because of the premature stop codon. Treatment of the cells with G418 significantly increased the expression of the full-length cotransporter, as assessed by immunoblot analysis. Furthermore, immunocytochemical studies demonstrated that G418 treatment induced cotransporter expression on the plasma membrane whereas in the absence of G418, NBCe1-A-Q29X was not expressed. In HEK293-H cells transfected with the NBCe1-A-Q29X mutant not treated with G418, NBCe1-A-mediated flux was not detectable. In contrast, in cells transfected with the NBCe1-A-Q29X mutant, G418 treatment induced Na+- and HCO3−-dependent transport that did not differ from wild-type NBCe1-A function. G418 treatment in mock-transfected cells was without effect. In conclusion, G418 induces ribosomal read-through of the NBCe1-A-Q29X mutation in HEK293-H cells. These findings represent the first evidence that in the presence of the NBCe1-A-Q29X mutation that causes

  14. Mutations in the Gene Encoding the Wnt-Signaling Component R-Spondin 4 (RSPO4) Cause Autosomal Recessive Anonychia

    PubMed Central

    Bergmann, C. ; Senderek, J. ; Anhuf, D. ; Thiel, C. T. ; Ekici, A. B. ; Poblete-Gutiérrez, P. ; van Steensel, M. ; Seelow, D. ; Nürnberg, G. ; Schild, H. H. ; Nürnberg, P. ; Reis, A. ; Frank, J. ; Zerres, K. 

    2006-01-01

    Anonychia is an autosomal recessive disorder characterized by the congenital absence of finger- and toenails. In a large German nonconsanguineous family with four affected and five unaffected siblings with isolated total congenital anonychia, we performed genomewide mapping and showed linkage to 20p13. Analysis of the RSPO4 gene within this interval revealed a frameshift and a nonconservative missense mutation in exon 2 affecting the highly conserved first furin-like cysteine-rich domain. Both mutations were not present among controls and were shown to segregate with the disease phenotype. RSPO4 is a member of the recently described R-spondin family of secreted proteins that play a major role in activating the Wnt/β-catenin signaling pathway. Wnt signaling is evolutionarily conserved and plays a pivotal role in embryonic development, growth regulation of multiple tissues, and cancer development. Our findings add to the increasing body of evidence indicating that mesenchymal-epithelial interactions are crucial in nail development and put anonychia on the growing list of congenital malformation syndromes caused by Wnt-signaling–pathway defects. To the best of our knowledge, this is the first gene known to be responsible for an isolated, nonsyndromic nail disorder. PMID:17186469

  15. Mutations in BRAT1 cause autosomal recessive progressive encephalopathy: Report of a Spanish patient

    PubMed Central

    Fernández-Jáen, Alberto; Álvarez, Sara; So, Eui Young; Ouchi, Toru; de la Peña, Mar Jiménez; Duat, Anna; Fernández-Mayoralas, Daniel Martín; Fernández-Perrone, Ana Laura; Albert, Jacobo; Calleja-Pérez, Beatriz

    2016-01-01

    We describe a 4-year-old male child born to non-consanguineous Spanish parents with progressive encephalopathy (PE), microcephaly, and hypertonia. Whole exome sequencing revealed compound heterozygous BRAT1 mutations [c.1564G > A (p.Glu522Lys) and c.638dup (p.Val214Glyfs*189)]. Homozygous and compound heterozygous BRAT1 mutations have been described in patients with lethal neonatal rigidity and multifocal seizure syndrome (MIM# 614498). The seven previously described patients suffered from uncontrolled seizures, and all of those patients died in their first months of life. BRAT1 acts as a regulator of cellular proliferation and migration and is required for mitochondrial function. The loss of these functions may explain the cerebral atrophy observed in this case of PE. This case highlights the extraordinary potential of next generation technologies for the diagnosis of rare genetic diseases, including PE. Making a prompt diagnosis of PE is important for genetic counseling and disease management. PMID:26947546

  16. Recessive and Dominant De Novo ITPR1 Mutations Cause Gillespie Syndrome

    PubMed Central

    Gerber, Sylvie; Alzayady, Kamil J.; Burglen, Lydie; Brémond-Gignac, Dominique; Marchesin, Valentina; Roche, Olivier; Rio, Marlène; Funalot, Benoit; Calmon, Raphaël; Durr, Alexandra; Gil-da-Silva-Lopes, Vera Lucia; Ribeiro Bittar, Maria Fernanda; Orssaud, Christophe; Héron, Bénédicte; Ayoub, Edward; Berquin, Patrick; Bahi-Buisson, Nadia; Bole, Christine; Masson, Cécile; Munnich, Arnold; Simons, Matias; Delous, Marion; Dollfus, Helene; Boddaert, Nathalie; Lyonnet, Stanislas; Kaplan, Josseline; Calvas, Patrick; Yule, David I.; Rozet, Jean-Michel; Fares Taie, Lucas

    2016-01-01

    Gillespie syndrome (GS) is a rare variant form of aniridia characterized by non-progressive cerebellar ataxia, intellectual disability, and iris hypoplasia. Unlike the more common dominant and sporadic forms of aniridia, there has been no significant association with PAX6 mutations in individuals with GS and the mode of inheritance of the disease had long been regarded as uncertain. Using a combination of trio-based whole-exome sequencing and Sanger sequencing in five simplex GS-affected families, we found homozygous or compound heterozygous truncating mutations (c.4672C>T [p.Gln1558∗], c.2182C>T [p.Arg728∗], c.6366+3A>T [p.Gly2102Valfs5∗], and c.6664+5G>T [p.Ala2221Valfs23∗]) and de novo heterozygous mutations (c.7687_7689del [p.Lys2563del] and c.7659T>G [p.Phe2553Leu]) in the inositol 1,4,5-trisphosphate receptor type 1 gene (ITPR1). ITPR1 encodes one of the three members of the IP3-receptors family that form Ca2+ release channels localized predominantly in membranes of endoplasmic reticulum Ca2+ stores. The truncation mutants, which encompass the IP3-binding domain and varying lengths of the modulatory domain, did not form functional channels when produced in a heterologous cell system. Furthermore, ITPR1 p.Lys2563del mutant did not form IP3-induced Ca2+ channels but exerted a negative effect when co-produced with wild-type ITPR1 channel activity. In total, these results demonstrate biallelic and monoallelic ITPR1 mutations as the underlying genetic defects for Gillespie syndrome, further extending the spectrum of ITPR1-related diseases. PMID:27108797

  17. Recessive and Dominant De Novo ITPR1 Mutations Cause Gillespie Syndrome.

    PubMed

    Gerber, Sylvie; Alzayady, Kamil J; Burglen, Lydie; Brémond-Gignac, Dominique; Marchesin, Valentina; Roche, Olivier; Rio, Marlène; Funalot, Benoit; Calmon, Raphaël; Durr, Alexandra; Gil-da-Silva-Lopes, Vera Lucia; Ribeiro Bittar, Maria Fernanda; Orssaud, Christophe; Héron, Bénédicte; Ayoub, Edward; Berquin, Patrick; Bahi-Buisson, Nadia; Bole, Christine; Masson, Cécile; Munnich, Arnold; Simons, Matias; Delous, Marion; Dollfus, Helene; Boddaert, Nathalie; Lyonnet, Stanislas; Kaplan, Josseline; Calvas, Patrick; Yule, David I; Rozet, Jean-Michel; Fares Taie, Lucas

    2016-05-01

    Gillespie syndrome (GS) is a rare variant form of aniridia characterized by non-progressive cerebellar ataxia, intellectual disability, and iris hypoplasia. Unlike the more common dominant and sporadic forms of aniridia, there has been no significant association with PAX6 mutations in individuals with GS and the mode of inheritance of the disease had long been regarded as uncertain. Using a combination of trio-based whole-exome sequencing and Sanger sequencing in five simplex GS-affected families, we found homozygous or compound heterozygous truncating mutations (c.4672C>T [p.Gln1558(∗)], c.2182C>T [p.Arg728(∗)], c.6366+3A>T [p.Gly2102Valfs5(∗)], and c.6664+5G>T [p.Ala2221Valfs23(∗)]) and de novo heterozygous mutations (c.7687_7689del [p.Lys2563del] and c.7659T>G [p.Phe2553Leu]) in the inositol 1,4,5-trisphosphate receptor type 1 gene (ITPR1). ITPR1 encodes one of the three members of the IP3-receptors family that form Ca(2+) release channels localized predominantly in membranes of endoplasmic reticulum Ca(2+) stores. The truncation mutants, which encompass the IP3-binding domain and varying lengths of the modulatory domain, did not form functional channels when produced in a heterologous cell system. Furthermore, ITPR1 p.Lys2563del mutant did not form IP3-induced Ca(2+) channels but exerted a negative effect when co-produced with wild-type ITPR1 channel activity. In total, these results demonstrate biallelic and monoallelic ITPR1 mutations as the underlying genetic defects for Gillespie syndrome, further extending the spectrum of ITPR1-related diseases. PMID:27108797

  18. GNB5 Mutations Cause an Autosomal-Recessive Multisystem Syndrome with Sinus Bradycardia and Cognitive Disability.

    PubMed

    Lodder, Elisabeth M; De Nittis, Pasquelena; Koopman, Charlotte D; Wiszniewski, Wojciech; Moura de Souza, Carolina Fischinger; Lahrouchi, Najim; Guex, Nicolas; Napolioni, Valerio; Tessadori, Federico; Beekman, Leander; Nannenberg, Eline A; Boualla, Lamiae; Blom, Nico A; de Graaff, Wim; Kamermans, Maarten; Cocciadiferro, Dario; Malerba, Natascia; Mandriani, Barbara; Akdemir, Zeynep Hande Coban; Fish, Richard J; Eldomery, Mohammad K; Ratbi, Ilham; Wilde, Arthur A M; de Boer, Teun; Simonds, William F; Neerman-Arbez, Marguerite; Sutton, V Reid; Kok, Fernando; Lupski, James R; Reymond, Alexandre; Bezzina, Connie R; Bakkers, Jeroen; Merla, Giuseppe

    2016-09-01

    GNB5 encodes the G protein β subunit 5 and is involved in inhibitory G protein signaling. Here, we report mutations in GNB5 that are associated with heart-rate disturbance, eye disease, intellectual disability, gastric problems, hypotonia, and seizures in nine individuals from six families. We observed an association between the nature of the variants and clinical severity; individuals with loss-of-function alleles had more severe symptoms, including substantial developmental delay, speech defects, severe hypotonia, pathological gastro-esophageal reflux, retinal disease, and sinus-node dysfunction, whereas related heterozygotes harboring missense variants presented with a clinically milder phenotype. Zebrafish gnb5 knockouts recapitulated the phenotypic spectrum of affected individuals, including cardiac, neurological, and ophthalmological abnormalities, supporting a direct role of GNB5 in the control of heart rate, hypotonia, and vision. PMID:27523599

  19. GNB5 Mutations Cause an Autosomal-Recessive Multisystem Syndrome with Sinus Bradycardia and Cognitive Disability.

    PubMed

    Lodder, Elisabeth M; De Nittis, Pasquelena; Koopman, Charlotte D; Wiszniewski, Wojciech; Moura de Souza, Carolina Fischinger; Lahrouchi, Najim; Guex, Nicolas; Napolioni, Valerio; Tessadori, Federico; Beekman, Leander; Nannenberg, Eline A; Boualla, Lamiae; Blom, Nico A; de Graaff, Wim; Kamermans, Maarten; Cocciadiferro, Dario; Malerba, Natascia; Mandriani, Barbara; Akdemir, Zeynep Hande Coban; Fish, Richard J; Eldomery, Mohammad K; Ratbi, Ilham; Wilde, Arthur A M; de Boer, Teun; Simonds, William F; Neerman-Arbez, Marguerite; Sutton, V Reid; Kok, Fernando; Lupski, James R; Reymond, Alexandre; Bezzina, Connie R; Bakkers, Jeroen; Merla, Giuseppe

    2016-09-01

    GNB5 encodes the G protein β subunit 5 and is involved in inhibitory G protein signaling. Here, we report mutations in GNB5 that are associated with heart-rate disturbance, eye disease, intellectual disability, gastric problems, hypotonia, and seizures in nine individuals from six families. We observed an association between the nature of the variants and clinical severity; individuals with loss-of-function alleles had more severe symptoms, including substantial developmental delay, speech defects, severe hypotonia, pathological gastro-esophageal reflux, retinal disease, and sinus-node dysfunction, whereas related heterozygotes harboring missense variants presented with a clinically milder phenotype. Zebrafish gnb5 knockouts recapitulated the phenotypic spectrum of affected individuals, including cardiac, neurological, and ophthalmological abnormalities, supporting a direct role of GNB5 in the control of heart rate, hypotonia, and vision.

  20. Mutations in the 3β-Hydroxysterol Δ24-Reductase Gene Cause Desmosterolosis, an Autosomal Recessive Disorder of Cholesterol Biosynthesis

    PubMed Central

    Waterham, Hans R.; Koster, Janet; Romeijn, Gerrit Jan; Hennekam, Raoul C.M.; Vreken, Peter; Andersson, Hans C.; FitzPatrick, David R.; Kelley, Richard. I.; Wanders, Ronald J. A.

    2001-01-01

    Desmosterolosis is a rare autosomal recessive disorder characterized by multiple congenital anomalies. Patients with desmosterolosis have elevated levels of the cholesterol precursor desmosterol, in plasma, tissue, and cultured cells; this abnormality suggests a deficiency of the enzyme 3β-hydroxysterol Δ24-reductase (DHCR24), which, in cholesterol biosynthesis, catalyzes the reduction of the Δ24 double bond of sterol intermediates. We identified the human DHCR24 cDNA, by the similarity between the encoded protein and a recently characterized plant enzyme—DWF1/DIM, from Arabidopsis thaliana—catalyzing a different but partially similar reaction in steroid/sterol biosynthesis in plants. Heterologous expression, in the yeast Saccharomyces cerevisiae, of the DHCR24 cDNA, followed by enzyme-activity measurements, confirmed that it encodes DHCR24. The encoded DHCR24 protein has a calculated molecular weight of 60.1 kD, contains a potential N-terminal secretory-signal sequence as well as at least one putative transmembrane helix, and is a member of a recently defined family of flavin adenine dinucleotide (FAD)–dependent oxidoreductases. Conversion of desmosterol to cholesterol by DHCR24 in vitro is strictly dependent on reduced nicotinamide adenine dinucleotide phosphate and is increased twofold by the addition of FAD to the assay. The corresponding gene, DHCR24, was identified by database searching, spans ∼46.4 kb, is localized to chromosome 1p31.1-p33, and comprises nine exons and eight introns. Sequence analysis of DHCR24 in two patients with desmosterolosis revealed four different missense mutations, which were shown, by functional expression, in yeast, of the patient alleles, to be disease causing. Our data demonstrate that desmosterolosis is a cholesterol-biosynthesis disorder caused by mutations in DHCR24. PMID:11519011

  1. A Population-Based Study of Autosomal-Recessive Disease-Causing Mutations in a Founder Population

    PubMed Central

    Chong, Jessica X.; Ouwenga, Rebecca; Anderson, Rebecca L.; Waggoner, Darrel J.; Ober, Carole

    2012-01-01

    The decreasing cost of whole-genome and whole-exome sequencing has resulted in a renaissance for identifying Mendelian disease mutations, and for the first time it is possible to survey the distribution and characteristics of these mutations in large population samples. We conducted carrier screening for all autosomal-recessive (AR) mutations known to be present in members of a founder population and revealed surprisingly high carrier frequencies for many of these mutations. By utilizing the rich demographic, genetic, and phenotypic data available on these subjects and simulations in the exact pedigree that these individuals belong to, we show that the majority of mutations were most likely introduced into the population by a single founder and then drifted to the high carrier frequencies observed. We further show that although there is an increased incidence of AR diseases overall, the mean carrier burden is likely to be lower in the Hutterites than in the general population. Finally, on the basis of simulations, we predict the presence of 30 or more undiscovered recessive mutations among these subjects, and this would at least double the number of AR diseases that have been reported in this isolated population. PMID:22981120

  2. Whole-exome sequencing reveals a novel frameshift mutation in the FAM161A gene causing autosomal recessive retinitis pigmentosa in the Indian population.

    PubMed

    Zhou, Yu; Saikia, Bibhuti B; Jiang, Zhilin; Zhu, Xiong; Liu, Yuqing; Huang, Lulin; Kim, Ramasamy; Yang, Yin; Qu, Chao; Hao, Fang; Gong, Bo; Tai, Zhengfu; Niu, Lihong; Yang, Zhenglin; Sundaresan, Periasamy; Zhu, Xianjun

    2015-10-01

    Retinitis pigmentosa (RP) is a heterogenous group of inherited retinal degenerations caused by mutations in at least 50 genes. To identify genetic mutations underlying autosomal recessive RP (arRP), we performed whole-exome sequencing study on two consanguineous marriage Indian families (RP-252 and RP-182) and 100 sporadic RP patients. Here we reported novel mutation in FAM161A in RP-252 and RP-182 with two patients affected with RP in each family. The FAM161A gene was identified as the causative gene for RP28, an autosomal recessive form of RP. By whole-exome sequencing we identified several homozygous genomic regions, one of which included the recently identified FAM161A gene mutated in RP28-linked arRP. Sequencing analysis revealed the presence of a novel homozygous frameshift mutation p.R592FsX2 in both patients of family RP-252 and family RP-182. In 100 sporadic Indian RP patients, this novel homozygous frameshift mutation p.R592FsX2 was identified in one sporadic patient ARRP-S-I-46 by whole-exome sequencing and validated by Sanger sequencing. Meanwhile, this homozygous frameshift mutation was absent in 1000 ethnicity-matched control samples screened by direct Sanger sequencing. In conclusion, we identified a novel homozygous frameshift mutations of RP28-linked RP gene FAM161A in Indian population.

  3. 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.

  4. Homozygous SLC6A17 Mutations Cause Autosomal-Recessive Intellectual Disability with Progressive Tremor, Speech Impairment, and Behavioral Problems

    PubMed Central

    Iqbal, Zafar; Willemsen, Marjolein H.; Papon, Marie-Amélie; Musante, Luciana; Benevento, Marco; Hu, Hao; Venselaar, Hanka; Wissink-Lindhout, Willemijn M.; Vulto-van Silfhout, Anneke T.; Vissers, Lisenka E.L.M.; de Brouwer, Arjan P.M.; Marouillat, Sylviane; Wienker, Thomas F.; Ropers, Hans Hilger; Kahrizi, Kimia; Nadif Kasri, Nael; Najmabadi, Hossein; Laumonnier, Frédéric; Kleefstra, Tjitske; van Bokhoven, Hans

    2015-01-01

    We report on Dutch and Iranian families with affected individuals who present with moderate to severe intellectual disability and additional phenotypes including progressive tremor, speech impairment, and behavioral problems in certain individuals. A combination of exome sequencing and homozygosity mapping revealed homozygous mutations c.484G>A (p.Gly162Arg) and c.1898C>G (p.Pro633Arg) in SLC6A17. SLC6A17 is predominantly expressed in the brain, encodes a synaptic vesicular transporter of neutral amino acids and glutamate, and plays an important role in the regulation of glutamatergic synapses. Prediction programs and 3D modeling suggest that the identified mutations are deleterious to protein function. To directly test the functional consequences, we investigated the neuronal subcellular localization of overexpressed wild-type and mutant variants in mouse primary hippocampal neuronal cells. Wild-type protein was present in soma, axons, dendrites, and dendritic spines. p.Pro633Arg altered SLC6A17 was found in soma and proximal dendrites but did not reach spines. p.Gly162Arg altered SLC6A17 showed a normal subcellular distribution but was associated with an abnormal neuronal morphology mainly characterized by the loss of dendritic spines. In summary, our genetic findings implicate homozygous SLC6A17 mutations in autosomal-recessive intellectual disability, and their pathogenic role is strengthened by genetic evidence and in silico and in vitro functional analyses. PMID:25704603

  5. Whole-Exome Sequencing Identifies LRIT3 Mutations as a Cause of Autosomal-Recessive Complete Congenital Stationary Night Blindness

    PubMed Central

    Zeitz, Christina; Jacobson, Samuel G.; Hamel, Christian P.; Bujakowska, Kinga; Neuillé, Marion; Orhan, Elise; Zanlonghi, Xavier; Lancelot, Marie-Elise; Michiels, Christelle; Schwartz, Sharon B.; Bocquet, Béatrice; Antonio, Aline; Audier, Claire; Letexier, Mélanie; Saraiva, Jean-Paul; Luu, Tien D.; Sennlaub, Florian; Nguyen, Hoan; Poch, Olivier; Dollfus, Hélène; Lecompte, Odile; Kohl, Susanne; Sahel, José-Alain; Bhattacharya, Shomi S.; Audo, Isabelle

    2013-01-01

    Congenital stationary night blindness (CSNB) is a clinically and genetically heterogeneous retinal disorder. Two forms can be distinguished clinically: complete CSNB (cCSNB) and incomplete CSNB. Individuals with cCSNB have visual impairment under low-light conditions and show a characteristic electroretinogram (ERG). The b-wave amplitude is severely reduced in the dark-adapted state of the ERG, representing abnormal function of ON bipolar cells. Furthermore, individuals with cCSNB can show other ocular features such as nystagmus, myopia, and strabismus and can have reduced visual acuity and abnormalities of the cone ERG waveform. The mode of inheritance of this form can be X-linked or autosomal recessive, and the dysfunction of four genes (NYX, GRM6, TRPM1, and GPR179) has been described so far. Whole-exome sequencing in one simplex cCSNB case lacking mutations in the known genes led to the identification of a missense mutation (c.983G>A [p.Cys328Tyr]) and a nonsense mutation (c.1318C>T [p.Arg440∗]) in LRIT3, encoding leucine-rich-repeat (LRR), immunoglobulin-like, and transmembrane-domain 3 (LRIT3). Subsequent Sanger sequencing of 89 individuals with CSNB identified another cCSNB case harboring a nonsense mutation (c.1151C>G [p.Ser384∗]) and a deletion predicted to lead to a premature stop codon (c.1538_1539del [p.Ser513Cysfs∗59]) in the same gene. Human LRIT3 antibody staining revealed in the outer plexiform layer of the human retina a punctate-labeling pattern resembling the dendritic tips of bipolar cells; similar patterns have been observed for other proteins implicated in cCSNB. The exact role of this LRR protein in cCSNB remains to be elucidated. PMID:23246293

  6. An unusual clinical severity of 16p11.2 deletion syndrome caused by unmasked recessive mutation of CLN3.

    PubMed

    Pebrel-Richard, Céline; Debost-Legrand, Anne; Eymard-Pierre, Eléonore; Greze, Victoria; Kemeny, Stéphan; Gay-Bellile, Mathilde; Gouas, Laetitia; Tchirkov, Andreï; Vago, Philippe; Goumy, Carole; Francannet, Christine

    2014-03-01

    With the introduction of array comparative genomic hybridization (aCGH) techniques in the diagnostic setting of patients with developmental delay and congenital malformations, many new microdeletion syndromes have been recognized. One of these recently recognized microdeletion syndromes is the 16p11.2 deletion syndrome, associated with variable clinical outcomes including developmental delay, autism spectrum disorder, epilepsy, and obesity, but also apparently normal phenotype. We report on a 16-year-old patient with developmental delay, exhibiting retinis pigmentosa with progressive visual failure from the age of 9 years, ataxia, and peripheral neuropathy. Chromosomal microarray analysis identified a 1.7-Mb 16p11.2 deletion encompassing the 593-kb common deletion (∼29.5 to ∼30.1 Mb; Hg18) and the 220-kb distal deletion (∼28.74 to ∼28.95 Mb; Hg18) that partially included the CLN3 gene. As the patient's clinical findings were different from usual 16p11.2 microdeletion phenotypes and showed some features reminiscent of juvenile neuronal ceroid-lipofuscinosis (JNCL, Batten disease, OMIM 204200), we suspected and confirmed a mutation of the remaining CLN3 allele. This case further illustrates that unmasking of hemizygous recessive mutations by chromosomal deletion represents one explanation for the phenotypic variability observed in chromosomal deletion disorders.

  7. Mutations in CNNM4 Cause Jalili Syndrome, Consisting of Autosomal-Recessive Cone-Rod Dystrophy and Amelogenesis Imperfecta

    PubMed Central

    Parry, David A.; Mighell, Alan J.; El-Sayed, Walid; Shore, Roger C.; Jalili, Ismail K.; Dollfus, Hélène; Bloch-Zupan, Agnes; Carlos, Roman; Carr, Ian M.; Downey, Louise M.; Blain, Katharine M.; Mansfield, David C.; Shahrabi, Mehdi; Heidari, Mansour; Aref, Parissa; Abbasi, Mohsen; Michaelides, Michel; Moore, Anthony T.; Kirkham, Jennifer; Inglehearn, Chris F.

    2009-01-01

    The combination of recessively inherited cone-rod dystrophy (CRD) and amelogenesis imperfecta (AI) was first reported by Jalili and Smith in 1988 in a family subsequently linked to a locus on chromosome 2q11, and it has since been reported in a second small family. We have identified five further ethnically diverse families cosegregating CRD and AI. Phenotypic characterization of teeth and visual function in the published and new families reveals a consistent syndrome in all seven families, and all link or are consistent with linkage to 2q11, confirming the existence of a genetically homogenous condition that we now propose to call Jalili syndrome. Using a positional-candidate approach, we have identified mutations in the CNNM4 gene, encoding a putative metal transporter, accounting for the condition in all seven families. Nine mutations are described in all, three missense, three terminations, two large deletions, and a single base insertion. We confirmed expression of Cnnm4 in the neural retina and in ameloblasts in the developing tooth, suggesting a hitherto unknown connection between tooth biomineralization and retinal function. The identification of CNNM4 as the causative gene for Jalili syndrome, characterized by syndromic CRD with AI, has the potential to provide new insights into the roles of metal transport in visual function and biomineralization. PMID:19200525

  8. Buried in the Middle but Guilty: Intronic Mutations in the TCIRG1 Gene Cause Human Autosomal Recessive Osteopetrosis.

    PubMed

    Palagano, Eleonora; Blair, Harry C; Pangrazio, Alessandra; Tourkova, Irina; Strina, Dario; Angius, Andrea; Cuccuru, Gianmauro; Oppo, Manuela; Uva, Paolo; Van Hul, Wim; Boudin, Eveline; Superti-Furga, Andrea; Faletra, Flavio; Nocerino, Agostino; Ferrari, Matteo C; Grappiolo, Guido; Monari, Marta; Montanelli, Alessandro; Vezzoni, Paolo; Villa, Anna; Sobacchi, Cristina

    2015-10-01

    Autosomal recessive osteopetrosis (ARO) is a rare genetic bone disease with genotypic and phenotypic heterogeneity, sometimes translating into delayed diagnosis and treatment. In particular, cases of intermediate severity often constitute a diagnostic challenge and represent good candidates for exome sequencing. Here, we describe the tortuous path to identification of the molecular defect in two siblings, in which osteopetrosis diagnosed in early childhood followed a milder course, allowing them to reach the adult age in relatively good conditions with no specific therapy. No clearly pathogenic mutation was identified either with standard amplification and resequencing protocols or with exome sequencing analysis. While evaluating the possible impact of a 3'UTR variant on the TCIRG1 expression, we found a novel single nucleotide change buried in the middle of intron 15 of the TCIRG1 gene, about 150 nucleotides away from the closest canonical splice site. By sequencing a number of independent cDNA clones covering exons 14 to 17, we demonstrated that this mutation reduced splicing efficiency but did not completely abrogate the production of the normal transcript. Prompted by this finding, we sequenced the same genomic region in 33 patients from our unresolved ARO cohort and found three additional novel single nucleotide changes in a similar location and with a predicted disruptive effect on splicing, further confirmed in one of them at the transcript level. Overall, we identified an intronic region in TCIRG1 that seems to be particularly prone to splicing mutations, allowing the production of a small amount of protein sufficient to reduce the severity of the phenotype usually associated with TCIRG1 defects. On this basis, we would recommend including TCIRG1 not only in the molecular work-up of severe infantile osteopetrosis but also in intermediate cases and carefully evaluating the possible effects of intronic changes. PMID:25829125

  9. Buried in the Middle but Guilty: Intronic Mutations in the TCIRG1 Gene Cause Human Autosomal Recessive Osteopetrosis.

    PubMed

    Palagano, Eleonora; Blair, Harry C; Pangrazio, Alessandra; Tourkova, Irina; Strina, Dario; Angius, Andrea; Cuccuru, Gianmauro; Oppo, Manuela; Uva, Paolo; Van Hul, Wim; Boudin, Eveline; Superti-Furga, Andrea; Faletra, Flavio; Nocerino, Agostino; Ferrari, Matteo C; Grappiolo, Guido; Monari, Marta; Montanelli, Alessandro; Vezzoni, Paolo; Villa, Anna; Sobacchi, Cristina

    2015-10-01

    Autosomal recessive osteopetrosis (ARO) is a rare genetic bone disease with genotypic and phenotypic heterogeneity, sometimes translating into delayed diagnosis and treatment. In particular, cases of intermediate severity often constitute a diagnostic challenge and represent good candidates for exome sequencing. Here, we describe the tortuous path to identification of the molecular defect in two siblings, in which osteopetrosis diagnosed in early childhood followed a milder course, allowing them to reach the adult age in relatively good conditions with no specific therapy. No clearly pathogenic mutation was identified either with standard amplification and resequencing protocols or with exome sequencing analysis. While evaluating the possible impact of a 3'UTR variant on the TCIRG1 expression, we found a novel single nucleotide change buried in the middle of intron 15 of the TCIRG1 gene, about 150 nucleotides away from the closest canonical splice site. By sequencing a number of independent cDNA clones covering exons 14 to 17, we demonstrated that this mutation reduced splicing efficiency but did not completely abrogate the production of the normal transcript. Prompted by this finding, we sequenced the same genomic region in 33 patients from our unresolved ARO cohort and found three additional novel single nucleotide changes in a similar location and with a predicted disruptive effect on splicing, further confirmed in one of them at the transcript level. Overall, we identified an intronic region in TCIRG1 that seems to be particularly prone to splicing mutations, allowing the production of a small amount of protein sufficient to reduce the severity of the phenotype usually associated with TCIRG1 defects. On this basis, we would recommend including TCIRG1 not only in the molecular work-up of severe infantile osteopetrosis but also in intermediate cases and carefully evaluating the possible effects of intronic changes.

  10. [Population frequency and age of c.806C > T mutation in CYB5R3 gene as cause of recessive congenital methemoglobinemia in Yakutia].

    PubMed

    Galeeva, N M; Voevoda, M I; Spiridonova, M G; Stepanov, V A; Poliakov, A V

    2013-04-01

    Type-1recessive congenital methemoglobinemia (RCM) is a rare autosomal disease characterized by a deficiency of the soluble form of nicotineamide adenine dinucleotide (NADH)-cytochrome b5 reductase (b5R) and clinically manifests as cyanosis of skin and mucous membranes. In the Russian Federation, type-I RCM is widely disturbed in Yakutia due to the local founder effect. The molecular genetics cause of type-I RCM in Yakutia is mutation c.806C > T in the CYB5R3 gene. In this work we used 13 polymorphic markers, which flanking the CYB5R3 gene to establish the founder haplotype. The age of the mutation was estimated as about 285 +/- 135 years. In this work, we have evaluated the frequency of the c.806 C > T mutation in Yakutia, which averaged 55 : 1000 Yakuts. The calculated frequency of disease was 1: 1250 Yakuts. PMID:23866629

  11. Hypomorphic Mutations in PGAP2, Encoding a GPI-Anchor-Remodeling Protein, Cause Autosomal-Recessive Intellectual Disability

    PubMed Central

    Hansen, Lars; Tawamie, Hasan; Murakami, Yoshiko; Mang, Yuan; ur Rehman, Shoaib; Buchert, Rebecca; Schaffer, Stefanie; Muhammad, Safia; Bak, Mads; Nöthen, Markus M.; Bennett, Eric P.; Maeda, Yusuke; Aigner, Michael; Reis, André; Kinoshita, Taroh; Tommerup, Niels; Baig, Shahid Mahmood; Abou Jamra, Rami

    2013-01-01

    PGAP2 encodes a protein involved in remodeling the glycosylphosphatidylinositol (GPI) anchor in the Golgi apparatus. After synthesis in the endoplasmic reticulum (ER), GPI anchors are transferred to the proteins and are remodeled while transported through the Golgi to the cell membrane. Germline mutations in six genes (PIGA, PIGL, PIGM, PIGV, PIGN, and PIGO) in the ER-located part of the GPI-anchor-biosynthesis pathway have been reported, and all are associated with phenotypes extending from malformation and lethality to severe intellectual disability, epilepsy, minor dysmorphisms, and elevated alkaline phosphatase (ALP). We performed autozygosity mapping and ultra-deep sequencing followed by stringent filtering and identified two homozygous PGAP2 alterations, p.Tyr99Cys and p.Arg177Pro, in seven offspring with nonspecific autosomal-recessive intellectual disability from two consanguineous families. Rescue experiments with the altered proteins in PGAP2-deficient Chinese hamster ovary cell lines showed less expression of cell-surface GPI-anchored proteins DAF and CD59 than of the wild-type protein, substantiating the pathogenicity of the identified alterations. Furthermore, we observed a full rescue when we used strong promoters before the mutant cDNAs, suggesting a hypomorphic effect of the mutations. We report on alterations in the Golgi-located part of the GPI-anchor-biosynthesis pathway and extend the phenotypic spectrum of the GPI-anchor deficiencies to isolated intellectual disability with elevated ALP. GPI-anchor deficiencies can be interpreted within the concept of a disease family, and we propose that the severity of the phenotype is dependent on the location of the altered protein in the biosynthesis chain. PMID:23561846

  12. Mutations in LOXHD1, a Recessive-Deafness Locus, Cause Dominant Late-Onset Fuchs Corneal Dystrophy

    PubMed Central

    Riazuddin, S. Amer; Parker, David S.; McGlumphy, Elyse J.; Oh, Edwin C.; Iliff, Benjamin W.; Schmedt, Thore; Jurkunas, Ula; Schleif, Robert; Katsanis, Nicholas; Gottsch, John D.

    2012-01-01

    Fuchs corneal dystrophy (FCD) is a genetic disorder of the corneal endothelium and is the most common cause of corneal transplantation in the United States. Previously, we mapped a late-onset FCD locus, FCD2, on chromosome 18q. Here, we present next-generation sequencing of all coding exons in the FCD2 critical interval in a multigenerational pedigree in which FCD segregates as an autosomal-dominant trait. We identified a missense change in LOXHD1, a gene causing progressive hearing loss in humans, as the sole variant capable of explaining the phenotype in this pedigree. We observed LOXHD1 mRNA in cultured human corneal endothelial cells, whereas antibody staining of both human and mouse corneas showed staining in the corneal epithelium and endothelium. Corneal sections of the original proband were stained for LOXHD1 and demonstrated a distinct increase in antibody punctate staining in the endothelium and Descemet membrane; punctate staining was absent from both normal corneas and FCD corneas negative for causal LOXHD1 mutations. Subsequent interrogation of a cohort of >200 sporadic affected individuals identified another 15 heterozygous missense mutations that were absent from >800 control chromosomes. Furthermore, in silico analyses predicted that these mutations reside on the surface of the protein and are likely to affect the protein's interface and protein-protein interactions. Finally, expression of the familial LOXHD1 mutant allele as well as two sporadic mutations in cells revealed prominent cytoplasmic aggregates reminiscent of the corneal phenotype. All together, our data implicate rare alleles in LOXHD1 in the pathogenesis of FCD and highlight how different mutations in the same locus can potentially produce diverse phenotypes. PMID:22341973

  13. Recessive Mutations in TRMT10C Cause Defects in Mitochondrial RNA Processing and Multiple Respiratory Chain Deficiencies.

    PubMed

    Metodiev, Metodi D; Thompson, Kyle; Alston, Charlotte L; Morris, Andrew A M; He, Langping; Assouline, Zarah; Rio, Marlène; Bahi-Buisson, Nadia; Pyle, Angela; Griffin, Helen; Siira, Stefan; Filipovska, Aleksandra; Munnich, Arnold; Chinnery, Patrick F; McFarland, Robert; Rötig, Agnès; Taylor, Robert W

    2016-05-01

    Mitochondrial disorders are clinically and genetically diverse, with mutations in mitochondrial or nuclear genes able to cause defects in mitochondrial gene expression. Recently, mutations in several genes encoding factors involved in mt-tRNA processing have been identified to cause mitochondrial disease. Using whole-exome sequencing, we identified mutations in TRMT10C (encoding the mitochondrial RNase P protein 1 [MRPP1]) in two unrelated individuals who presented at birth with lactic acidosis, hypotonia, feeding difficulties, and deafness. Both individuals died at 5 months after respiratory failure. MRPP1, along with MRPP2 and MRPP3, form the mitochondrial ribonuclease P (mt-RNase P) complex that cleaves the 5' ends of mt-tRNAs from polycistronic precursor transcripts. Additionally, a stable complex of MRPP1 and MRPP2 has m(1)R9 methyltransferase activity, which methylates mt-tRNAs at position 9 and is vital for folding mt-tRNAs into their correct tertiary structures. Analyses of fibroblasts from affected individuals harboring TRMT10C missense variants revealed decreased protein levels of MRPP1 and an increase in mt-RNA precursors indicative of impaired mt-RNA processing and defective mitochondrial protein synthesis. The pathogenicity of the detected variants-compound heterozygous c.542G>T (p.Arg181Leu) and c.814A>G (p.Thr272Ala) changes in subject 1 and a homozygous c.542G>T (p.Arg181Leu) variant in subject 2-was validated by the functional rescue of mt-RNA processing and mitochondrial protein synthesis defects after lentiviral transduction of wild-type TRMT10C. Our study suggests that these variants affect MRPP1 protein stability and mt-tRNA processing without affecting m(1)R9 methyltransferase activity, identifying mutations in TRMT10C as a cause of mitochondrial disease and highlighting the importance of RNA processing for correct mitochondrial function.

  14. Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy.

    PubMed

    Chong, Jessica X; Caputo, Viviana; Phelps, Ian G; Stella, Lorenzo; Worgan, Lisa; Dempsey, Jennifer C; Nguyen, Alina; Leuzzi, Vincenzo; Webster, Richard; Pizzuti, Antonio; Marvin, Colby T; Ishak, Gisele E; Ardern-Holmes, Simone; Richmond, Zara; Bamshad, Michael J; Ortiz-Gonzalez, Xilma R; Tartaglia, Marco; Chopra, Maya; Doherty, Dan

    2016-04-01

    Infantile encephalopathies are a group of clinically and biologically heterogeneous disorders for which the genetic basis remains largely unknown. Here, we report a syndromic neonatal encephalopathy characterized by profound developmental disability, severe hypotonia, seizures, diminished respiratory drive requiring mechanical ventilation, brain atrophy, dysgenesis of the corpus callosum, cerebellar vermis hypoplasia, and facial dysmorphism. Biallelic inactivating mutations in TBCK (TBC1-domain-containing kinase) were independently identified by whole-exome sequencing as the cause of this condition in four unrelated families. Matching these families was facilitated by the sharing of phenotypic profiles and WES data in a recently released web-based tool (Geno2MP) that links phenotypic information to rare variants in families with Mendelian traits. TBCK is a putative GTPase-activating protein (GAP) for small GTPases of the Rab family and has been shown to control cell growth and proliferation, actin-cytoskeleton dynamics, and mTOR signaling. Two of the three mutations (c.376C>T [p.Arg126(∗)] and c.1363A>T [p.Lys455(∗)]) are predicted to truncate the protein, and loss of the major TBCK isoform was confirmed in primary fibroblasts from one affected individual. The third mutation, c.1532G>A (p.Arg511His), alters a conserved residue within the TBC1 domain. Structural analysis implicated Arg511 as a required residue for Rab-GAP function, and in silico homology modeling predicted impaired GAP function in the corresponding mutant. These results suggest that loss of Rab-GAP activity is the underlying mechanism of disease. In contrast to other disorders caused by dysregulated mTOR signaling associated with focal or global brain overgrowth, impaired TBCK function results in progressive loss of brain volume. PMID:27040692

  15. Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy

    PubMed Central

    Chong, Jessica X.; Caputo, Viviana; Phelps, Ian G.; Stella, Lorenzo; Worgan, Lisa; Dempsey, Jennifer C.; Nguyen, Alina; Leuzzi, Vincenzo; Webster, Richard; Pizzuti, Antonio; Marvin, Colby T.; Ishak, Gisele E.; Ardern-Holmes, Simone; Richmond, Zara; Bamshad, Michael J.; Ortiz-Gonzalez, Xilma R.; Tartaglia, Marco; Chopra, Maya; Doherty, Dan

    2016-01-01

    Infantile encephalopathies are a group of clinically and biologically heterogeneous disorders for which the genetic basis remains largely unknown. Here, we report a syndromic neonatal encephalopathy characterized by profound developmental disability, severe hypotonia, seizures, diminished respiratory drive requiring mechanical ventilation, brain atrophy, dysgenesis of the corpus callosum, cerebellar vermis hypoplasia, and facial dysmorphism. Biallelic inactivating mutations in TBCK (TBC1-domain-containing kinase) were independently identified by whole-exome sequencing as the cause of this condition in four unrelated families. Matching these families was facilitated by the sharing of phenotypic profiles and WES data in a recently released web-based tool (Geno2MP) that links phenotypic information to rare variants in families with Mendelian traits. TBCK is a putative GTPase-activating protein (GAP) for small GTPases of the Rab family and has been shown to control cell growth and proliferation, actin-cytoskeleton dynamics, and mTOR signaling. Two of the three mutations (c.376C>T [p.Arg126∗] and c.1363A>T [p.Lys455∗]) are predicted to truncate the protein, and loss of the major TBCK isoform was confirmed in primary fibroblasts from one affected individual. The third mutation, c.1532G>A (p.Arg511His), alters a conserved residue within the TBC1 domain. Structural analysis implicated Arg511 as a required residue for Rab-GAP function, and in silico homology modeling predicted impaired GAP function in the corresponding mutant. These results suggest that loss of Rab-GAP activity is the underlying mechanism of disease. In contrast to other disorders caused by dysregulated mTOR signaling associated with focal or global brain overgrowth, impaired TBCK function results in progressive loss of brain volume. PMID:27040692

  16. Recessive Inactivating Mutations in TBCK, Encoding a Rab GTPase-Activating Protein, Cause Severe Infantile Syndromic Encephalopathy.

    PubMed

    Chong, Jessica X; Caputo, Viviana; Phelps, Ian G; Stella, Lorenzo; Worgan, Lisa; Dempsey, Jennifer C; Nguyen, Alina; Leuzzi, Vincenzo; Webster, Richard; Pizzuti, Antonio; Marvin, Colby T; Ishak, Gisele E; Ardern-Holmes, Simone; Richmond, Zara; Bamshad, Michael J; Ortiz-Gonzalez, Xilma R; Tartaglia, Marco; Chopra, Maya; Doherty, Dan

    2016-04-01

    Infantile encephalopathies are a group of clinically and biologically heterogeneous disorders for which the genetic basis remains largely unknown. Here, we report a syndromic neonatal encephalopathy characterized by profound developmental disability, severe hypotonia, seizures, diminished respiratory drive requiring mechanical ventilation, brain atrophy, dysgenesis of the corpus callosum, cerebellar vermis hypoplasia, and facial dysmorphism. Biallelic inactivating mutations in TBCK (TBC1-domain-containing kinase) were independently identified by whole-exome sequencing as the cause of this condition in four unrelated families. Matching these families was facilitated by the sharing of phenotypic profiles and WES data in a recently released web-based tool (Geno2MP) that links phenotypic information to rare variants in families with Mendelian traits. TBCK is a putative GTPase-activating protein (GAP) for small GTPases of the Rab family and has been shown to control cell growth and proliferation, actin-cytoskeleton dynamics, and mTOR signaling. Two of the three mutations (c.376C>T [p.Arg126(∗)] and c.1363A>T [p.Lys455(∗)]) are predicted to truncate the protein, and loss of the major TBCK isoform was confirmed in primary fibroblasts from one affected individual. The third mutation, c.1532G>A (p.Arg511His), alters a conserved residue within the TBC1 domain. Structural analysis implicated Arg511 as a required residue for Rab-GAP function, and in silico homology modeling predicted impaired GAP function in the corresponding mutant. These results suggest that loss of Rab-GAP activity is the underlying mechanism of disease. In contrast to other disorders caused by dysregulated mTOR signaling associated with focal or global brain overgrowth, impaired TBCK function results in progressive loss of brain volume.

  17. 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.

  18. Recessive NEK9 mutation causes a lethal skeletal dysplasia with evidence of cell cycle and ciliary defects.

    PubMed

    Casey, Jillian P; Brennan, Kieran; Scheidel, Noemie; McGettigan, Paul; Lavin, Paul T; Carter, Stephen; Ennis, Sean; Dorkins, Huw; Ghali, Neeti; Blacque, Oliver E; Mc Gee, Margaret M; Murphy, Helen; Lynch, Sally Ann

    2016-05-01

    Skeletal dysplasias are a clinically and genetically heterogeneous group of bone and cartilage disorders. Whilst >450 skeletal dysplasias have been reported, 30% are genetically uncharacterized. We report two Irish Traveller families with a previously undescribed lethal skeletal dysplasia characterized by fetal akinesia, shortening of all long bones, multiple contractures, rib anomalies, thoracic dysplasia, pulmonary hypoplasia and protruding abdomen. Single nucleotide polymorphism homozygosity mapping and whole exome sequencing identified a novel homozygous stop-gain mutation in NEK9 (c.1489C>T; p.Arg497*) as the cause of this disorder. NEK9 encodes a never in mitosis gene A-related kinase involved in regulating spindle organization, chromosome alignment, cytokinesis and cell cycle progression. This is the first disorder to be associated with NEK9 in humans. Analysis of NEK9 protein expression and localization in patient fibroblasts showed complete loss of full-length NEK9 (107 kDa). Functional characterization of patient fibroblasts showed a significant reduction in cell proliferation and a delay in cell cycle progression. We also provide evidence to support possible ciliary associations for NEK9. Firstly, patient fibroblasts displayed a significant reduction in cilia number and length. Secondly, we show that the NEK9 orthologue in Caenorhabditis elegans, nekl-1, is almost exclusively expressed in a subset of ciliated cells, a strong indicator of cilia-related functions. In summary, we report the clinical and molecular characterization of a lethal skeletal dysplasia caused by NEK9 mutation and suggest that this disorder may represent a novel ciliopathy. PMID:26908619

  19. Mutations in CDC14A, Encoding a Protein Phosphatase Involved in Hair Cell Ciliogenesis, Cause Autosomal-Recessive Severe to Profound Deafness.

    PubMed

    Delmaghani, Sedigheh; Aghaie, Asadollah; Bouyacoub, Yosra; El Hachmi, Hala; Bonnet, Crystel; Riahi, Zied; Chardenoux, Sebastien; Perfettini, Isabelle; Hardelin, Jean-Pierre; Houmeida, Ahmed; Herbomel, Philippe; Petit, Christine

    2016-06-01

    By genetic linkage analysis in a large consanguineous Iranian family with eleven individuals affected by severe to profound congenital deafness, we were able to define a 2.8 Mb critical interval (at chromosome 1p21.2-1p21.1) for an autosomal-recessive nonsyndromic deafness locus (DFNB). Whole-exome sequencing allowed us to identify a CDC14A biallelic nonsense mutation, c.1126C>T (p.Arg376(∗)), which was present in the eight clinically affected individuals still alive. Subsequent screening of 115 unrelated individuals affected by severe or profound congenital deafness of unknown genetic cause led us to identify another CDC14A biallelic nonsense mutation, c.1015C>T (p.Arg339(∗)), in an individual originating from Mauritania. CDC14A encodes a protein tyrosine phosphatase. Immunofluorescence analysis of the protein distribution in the mouse inner ear showed a strong labeling of the hair cells' kinocilia. By using a morpholino strategy to knockdown cdc14a in zebrafish larvae, we found that the length of the kinocilia was reduced in inner-ear hair cells. Therefore, deafness caused by loss-of-function mutations in CDC14A probably arises from a morphogenetic defect of the auditory sensory cells' hair bundles, whose differentiation critically depends on the proper growth of their kinocilium.

  20. A missense mutation in ALDH18A1, encoding Delta1-pyrroline-5-carboxylate synthase (P5CS), causes an autosomal recessive neurocutaneous syndrome.

    PubMed

    Bicknell, Louise S; Pitt, James; Aftimos, Salim; Ramadas, Ram; Maw, Marion A; Robertson, Stephen P

    2008-10-01

    There are several rare syndromes combining wrinkled, redundant skin and neurological abnormalities. Although phenotypic overlap between conditions has suggested that some might be allelic to one another, the aetiology for many of them remains unknown. A consanguineous New Zealand Maori family has been characterised that segregates an autosomal recessive connective tissue disorder (joint dislocations, lax skin) associated with neurological abnormalities (severe global developmental delay, choreoathetosis) without metabolic abnormalities in four affected children. A genome-screen performed under a hypothesis of homozygosity by descent for an ancestral mutation, identified a locus at 10q23 (Z = 3.63). One gene within the candidate interval, ALDH18A1, encoding Delta1-pyrroline-5-carboxylate synthase (P5CS), was considered a plausible disease gene since a missense mutation had previously been shown to cause progressive neurodegeneration, cataracts, skin laxity, joint dislocations and metabolic derangement in a consanguineous Algerian family. A missense mutation, 2350C>T, was identified in ALDH18A1, which predicts the substitution H784Y. H784 is invariant across all phyla and lies within a previously unrecognised, conserved C-terminal motif in P5CS. In an in vivo assay of flux through this metabolic pathway using dermal fibroblasts obtained from an affected individual, proline and ornithine biosynthetic activity of P5CS was not affected by the H784Y substitution. These data suggest that P5CS may possess additional uncharacterised functions that affect connective tissue and central nervous system function.

  1. Autosomal-recessive cerebellar ataxia caused by a novel ADCK3 mutation that elongates the protein: clinical, genetic and biochemical characterisation

    PubMed Central

    Liu, Yo-Tsen; Hersheson, Joshua; Plagnol, Vincent; Fawcett, Katherine; Duberley, Kate E C; Preza, Elisavet; Hargreaves, Iain P; Chalasani, Annapurna; Laurá, Matilde; Wood, Nick W; Reilly, Mary M; Houlden, Henry

    2014-01-01

    Background The autosomal-recessive cerebellar ataxias (ARCA) are a clinically and genetically heterogeneous group of neurodegenerative disorders. The large number of ARCA genes leads to delay and difficulties obtaining an exact diagnosis in many patients and families. Ubiquinone (CoQ10) deficiency is one of the potentially treatable causes of ARCAs as some patients respond to CoQ10 supplementation. The AarF domain containing kinase 3 gene (ADCK3) is one of several genes associated with CoQ10 deficiency. ADCK3 encodes a mitochondrial protein which functions as an electron-transfer membrane protein complex in the mitochondrial respiratory chain (MRC). Methods We report two siblings from a consanguineous Pakistani family who presented with cerebellar ataxia and severe myoclonus from adolescence. Whole exome sequencing and biochemical assessment of fibroblasts were performed in the index patient. Results A novel homozygous frameshift mutation in ADCK3 (p.Ser616Leufs*114), was identified in both siblings. This frameshift mutation results in the loss of the stop codon, extending the coding protein by 81 amino acids. Significant CoQ10 deficiency and reduced MRC enzyme activities in the index patient's fibroblasts suggested that the mutant protein may reduce the efficiency of mitochondrial electron transfer. CoQ10 supplementation was initiated following these genetic and biochemical analyses. She gained substantial improvement in myoclonic movements, ataxic gait and dysarthric speech after treatment. Conclusion This study highlights the importance of diagnosing ADCK3 mutations and the potential benefit of treatment for patients. The identification of this new mutation broadens the phenotypic spectrum associated with ADCK3 mutations and provides further understanding of their pathogenic mechanism. PMID:24218524

  2. A mutation in SLC22A4 encoding an organic cation transporter expressed in the cochlea strial endothelium causes human recessive non-syndromic hearing loss DFNB60.

    PubMed

    Ben Said, Mariem; Grati, M'hamed; Ishimoto, Takahiro; Zou, Bing; Chakchouk, Imen; Ma, Qi; Yao, Qi; Hammami, Bouthaina; Yan, Denise; Mittal, Rahul; Nakamichi, Noritaka; Ghorbel, Abdelmonem; Neng, Lingling; Tekin, Mustafa; Shi, Xiao Rui; Kato, Yukio; Masmoudi, Saber; Lu, Zhongmin; Hmani, Mounira; Liu, Xuezhong

    2016-05-01

    The high prevalence/incidence of hearing loss (HL) in humans makes it the most common sensory defect. The majority of the cases are of genetic origin. Non-syndromic hereditary HL is extremely heterogeneous. Genetic approaches have been instrumental in deciphering genes that are crucial for auditory function. In this study, we first used NADf chip to exclude the implication of known North-African mutations in HL in a large consanguineous Tunisian family (FT13) affected by autosomal recessive non-syndromic HL (ARNSHL). We then performed genome-wide linkage analysis and assigned the deafness gene locus to ch:5q23.2-31.1, corresponding to the DFNB60 ARNSHL locus. Moreover, we performed whole exome sequencing on FT13 patient DNA and uncovered amino acid substitution p.Cys113Tyr in SLC22A4, a transporter of organic cations, cosegregating with HL in FT13 and therefore the cause of ARNSHL DFNB60. We also screened a cohort of small Tunisian HL families and uncovered an additional deaf proband of consanguineous parents that is homozygous for p.Cys113Tyr carried by the same microsatellite marker haplotype as in FT13, indicating that this mutation is ancestral. Using immunofluorescence, we found that Slc22a4 is expressed in stria vascularis (SV) endothelial cells of rodent cochlea and targets their apical plasma membrane. We also found Slc22a4 transcripts in our RNA-seq library from purified primary culture of mouse SV endothelial cells. Interestingly, p.Cys113Tyr mutation affects the trafficking of the transporter and severely alters ergothioneine uptake. We conclude that SLC22A4 is an organic cation transporter of the SV endothelium that is essential for hearing, and its mutation causes DFNB60 form of HL. PMID:27023905

  3. Biallelic Mutations in GNB3 Cause a Unique Form of Autosomal-Recessive Congenital Stationary Night Blindness.

    PubMed

    Vincent, Ajoy; Audo, Isabelle; Tavares, Erika; Maynes, Jason T; Tumber, Anupreet; Wright, Thomas; Li, Shuning; Michiels, Christelle; Condroyer, Christel; MacDonald, Heather; Verdet, Robert; Sahel, José-Alain; Hamel, Christian P; Zeitz, Christina; Héon, Elise

    2016-05-01

    Congenital stationary night blindness (CSNB) is a heterogeneous group of non-progressive inherited retinal disorders with characteristic electroretinogram (ERG) abnormalities. Riggs and Schubert-Bornschein are subtypes of CSNB and demonstrate distinct ERG features. Riggs CSNB demonstrates selective rod photoreceptor dysfunction and occurs due to mutations in genes encoding proteins involved in rod phototransduction cascade; night blindness is the only symptom and eye examination is otherwise normal. Schubert-Bornschein CSNB is a consequence of impaired signal transmission between the photoreceptors and bipolar cells. Schubert-Bornschein CSNB is subdivided into complete CSNB with an ON bipolar signaling defect and incomplete CSNB with both ON and OFF pathway involvement. Both subtypes are associated with variable degrees of night blindness or photophobia, reduced visual acuity, high myopia, and nystagmus. Whole-exome sequencing of a family screened negative for mutations in genes associated with CSNB identified biallelic mutations in the guanine nucleotide-binding protein subunit beta-3 gene (GNB3). Two siblings were compound heterozygous for a deletion (c.170_172delAGA [p.Lys57del]) and a nonsense mutation (c.1017G>A [p.Trp339(∗)]). The maternal aunt was homozygous for the nonsense mutation (c.1017G>A [p.Trp339(∗)]). Mutational analysis of GNB3 in a cohort of 58 subjects with CSNB identified a sporadic case individual with a homozygous GNB3 mutation (c.200C>T [p.Ser67Phe]). GNB3 encodes the β subunit of G protein heterotrimer (Gαβγ) and is known to modulate ON bipolar cell signaling and cone transducin function in mice. Affected human subjects showed an unusual CSNB phenotype with variable degrees of ON bipolar dysfunction and reduced cone sensitivity. This unique retinal disorder with dual anomaly in visual processing expands our knowledge about retinal signaling. PMID:27063057

  4. Mutations in the MGAT2 gene controlling complex N-glycan synthesis cause carbohydrate-deficient glycoprotein syndrome type II, an autosomal recessive disease with defective brain development

    SciTech Connect

    Tan, J.; Schachter, H.; Dunn, J.

    1996-10-01

    Carbohydrate-deficient glycoprotein syndrome (CDGS) type II is a multisystemic congenital disease with severe involvement of the nervous system. Two unrelated CDGS type II patients are shown to have point mutations (one patient having Ser{r_arrow}Phe and the other having His{r_arrow}Arg) in the catalytic domain of the gene MGAT2, encoding UDP-GlcNAc:{alpha}-6-D-mannoside {Beta}-1,2-N-ace-tylglucosaminyltransferase II (GnT II), an enzyme essential for biosynthesis of complex Asn-linked glycans. Both mutations caused both decreased expression of enzyme protein in a baculovirus/insect cell system and inactivation of enzyme activity. Restriction-endonuclease analysis of DNA from 23 blood relatives of one of these patients showed that 13 donors were heterozygotes; the other relatives and 21 unrelated donors were normal homozygotes. All heterozygotes showed a significant reduction (33%-68%) in mononuclear-cell GnT II activity. The data indicate that CDGS type II is an autosomal recessive disease and that complex Asn-linked glycans are essential for normal neurological development. 38 refs., 4 figs., 1 tab.

  5. New autosomal recessive mutations in aquaporin-2 causing nephrogenic diabetes insipidus through deficient targeting display normal expression in Xenopus oocytes.

    PubMed

    Leduc-Nadeau, Alexandre; Lussier, Yoann; Arthus, Marie-Françoise; Lonergan, Michèle; Martinez-Aguayo, Alejandro; Riveira-Munoz, Eva; Devuyst, Olivier; Bissonnette, Pierre; Bichet, Daniel G

    2010-06-15

    Aquaporin-2 (AQP2), located at the luminal side of the collecting duct principal cells, is a water channel responsible for the final concentration of urine. Lack of function, often occurring through mistargeting of mutated proteins, induces nephrogenic diabetes insipidus (NDI), a condition characterized by large urinary volumes. In the present study, two new mutations (K228E and V24A) identified in NDI-affected individuals from distinct families along with the already reported R187C were analysed in comparison to the wild-type protein (AQP2-wt) using Xenopus laevis oocytes and a mouse collecting duct cell-line (mIMCD-3). Initial data in oocytes showed that all mutations were adequately expressed at reduced levels when compared to AQP2-wt. K228E and V24A were found to be properly targeted at the plasma membrane and exhibited adequate functionality similar to AQP2-wt, as opposed to R187C which was retained in internal stores and was thus inactive. In coexpression studies using oocytes, R187C impeded the functionality of all other AQP2 variants while combinations with K228E, V24A and AQP2-wt only showed additive functionalities. When expressed in mIMCD-3 cells, forskolin treatment efficiently promoted the targeting of AQP2-wt at the plasma membrane (>90%) while K228E only weakly responded to the same treatment (approximately 20%) and both V24A and R187C remained completely insensitive to the treatment. We concluded that both V24A and K228E are intrinsically functional water channels that lack a proper response to vasopressin, which leads to NDI as found in both compound mutations studied (K228E + R187C and V24A + R187C). The discrepancies in plasma membrane targeting response found in both expression systems stress the need to evaluate such data using mammalian cell systems.

  6. 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

  7. A missense mutation in DCDC2 causes human recessive deafness DFNB66, likely by interfering with sensory hair cell and supporting cell cilia length regulation.

    PubMed

    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

    2015-05-01

    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.

  8. NEW BEST1 MUTATIONS IN AUTOSOMAL RECESSIVE BESTROPHINOPATHY

    PubMed Central

    FUNG, ADRIAN T.; YZER, SUZANNE; GOLDBERG, NAOMI; WANG, HAO; NISSEN, MICHAEL; GIOVANNINI, ALFONSO; MERRIAM, JOANNA E.; BUKANOVA, ELENA N.; CAI, CAROLYN; YANNUZZI, LAWRENCE A.; TSANG, STEPHEN H.; ALLIKMETS, RANDO

    2015-01-01

    Purpose To report the ocular phenotype in patients with autosomal recessive bestrophinopathy and carriers, and to describe novel BEST1 mutations. Methods Patients with clinically suspected and subsequently genetically proven autosomal recessive bestrophinopathy underwent full ophthalmic examination and investigation with fundus autofluorescence imaging, spectral domain optical coherence tomography, electroretinography, and electrooculography. Mutation analysis of the BEST1 gene was performed through direct Sanger sequencing. Results Five affected patients from four families were identified. Mean age was 16 years (range, 6–42 years). All affected patients presented with reduced visual acuity and bilateral, hyperautofluorescent subretinal yellowish deposits within the posterior pole. Spectral domain optical coherence tomography demonstrated submacular fluid and subretinal vitelliform material in all patients. A cystoid maculopathy was seen in all but one patient. In 1 patient, the location of the vitelliform material was seen to change over a follow-up period of 3 years despite relatively stable vision. Visual acuity and fundus changes were unresponsive to topical and systemic carbonic anhydrase inhibitors and systemic steroids. Carriers had normal ocular examinations including normal fundus autofluorescence. Three novel mutations were detected. Conclusion Three novel BEST1 mutations are described, suggesting that many deleterious variants in BEST1 resulting in haploinsufficiency are still unknown. Mutations causing autosomal recessive bestrophinopathy are mostly located outside of the exons that usually harbor vitelliform macular dystrophy–associated dominant mutations. PMID:25545482

  9. Autosomal Recessive HEM/Greenberg Skeletal Dysplasia Is Caused by 3β-Hydroxysterol Δ14-Reductase Deficiency Due to Mutations in the Lamin B Receptor Gene

    PubMed Central

    Waterham, Hans R.; Koster, Janet; Mooyer, Petra; Noort, Gerard van; Kelley, Richard I.; Wilcox, William R.; Wanders, Ronald J. A.; Hennekam, Raoul C. M.; Oosterwijk, Jan C.

    2003-01-01

    Hydrops-ectopic calcification-“moth-eaten” (HEM) or Greenberg skeletal dysplasia is an autosomal recessive chondrodystrophy with a lethal course, characterized by fetal hydrops, short limbs, and abnormal chondro-osseous calcification. We found elevated levels of cholesta-8,14-dien-3β-ol in cultured skin fibroblasts of an 18-wk-old fetus with HEM, compatible with a deficiency of the cholesterol biosynthetic enzyme 3β-hydroxysterol Δ14-reductase. Sequence analysis of two candidate genes encoding putative human sterol Δ14-reductases (TM7SF2 and LBR) identified a homozygous 1599–1605TCTTCTA→CTAGAAG substitution in exon 13 of the LBR gene encoding the lamin B receptor, which results in a truncated protein. Functional complementation of the HEM cells by transfection with control LBR cDNA confirmed that LBR encoded the defective sterol Δ14-reductase. Mutations in LBR recently have been reported also to cause Pelger-Huët anomaly, an autosomal dominant trait characterized by hypolobulated nuclei and abnormal chromatin structure in granulocytes. The fact that the healthy mother of the fetus showed hypolobulated nuclei in 60% of her granulocytes confirms that classic Pelger-Huët anomaly represents the heterozygous state of 3β-hydroxysterol Δ14-reductase deficiency. PMID:12618959

  10. Mutations in SLC13A5 Cause Autosomal-Recessive Epileptic Encephalopathy with Seizure Onset in the First Days of Life

    PubMed Central

    Thevenon, Julien; Milh, Mathieu; Feillet, François; St-Onge, Judith; Duffourd, Yannis; Jugé, Clara; Roubertie, Agathe; Héron, Delphine; Mignot, Cyril; Raffo, Emmanuel; Isidor, Bertrand; Wahlen, Sandra; Sanlaville, Damien; Villeneuve, Nathalie; Darmency-Stamboul, Véronique; Toutain, Annick; Lefebvre, Mathilde; Chouchane, Mondher; Huet, Frédéric; Lafon, Arnaud; de Saint Martin, Anne; Lesca, Gaetan; El Chehadeh, Salima; Thauvin-Robinet, Christel; Masurel-Paulet, Alice; Odent, Sylvie; Villard, Laurent; Philippe, Christophe; Faivre, Laurence; Rivière, Jean-Baptiste

    2014-01-01

    Epileptic encephalopathy (EE) refers to a clinically and genetically heterogeneous group of severe disorders characterized by seizures, abnormal interictal electro-encephalogram, psychomotor delay, and/or cognitive deterioration. We ascertained two multiplex families (including one consanguineous family) consistent with an autosomal-recessive inheritance pattern of EE. All seven affected individuals developed subclinical seizures as early as the first day of life, severe epileptic disease, and profound developmental delay with no facial dysmorphism. Given the similarity in clinical presentation in the two families, we hypothesized that the observed phenotype was due to mutations in the same gene, and we performed exome sequencing in three affected individuals. Analysis of rare variants in genes consistent with an autosomal-recessive mode of inheritance led to identification of mutations in SLC13A5, which encodes the cytoplasmic sodium-dependent citrate carrier, notably expressed in neurons. Disease association was confirmed by cosegregation analysis in additional family members. Screening of 68 additional unrelated individuals with early-onset epileptic encephalopathy for SLC13A5 mutations led to identification of one additional subject with compound heterozygous mutations of SLC13A5 and a similar clinical presentation as the index subjects. Mutations affected key residues for sodium binding, which is critical for citrate transport. These findings underline the value of careful clinical characterization for genetic investigations in highly heterogeneous conditions such as EE and further highlight the role of citrate metabolism in epilepsy. PMID:24995870

  11. Mutations in SLC13A5 cause autosomal-recessive epileptic encephalopathy with seizure onset in the first days of life.

    PubMed

    Thevenon, Julien; Milh, Mathieu; Feillet, François; St-Onge, Judith; Duffourd, Yannis; Jugé, Clara; Roubertie, Agathe; Héron, Delphine; Mignot, Cyril; Raffo, Emmanuel; Isidor, Bertrand; Wahlen, Sandra; Sanlaville, Damien; Villeneuve, Nathalie; Darmency-Stamboul, Véronique; Toutain, Annick; Lefebvre, Mathilde; Chouchane, Mondher; Huet, Frédéric; Lafon, Arnaud; de Saint Martin, Anne; Lesca, Gaetan; El Chehadeh, Salima; Thauvin-Robinet, Christel; Masurel-Paulet, Alice; Odent, Sylvie; Villard, Laurent; Philippe, Christophe; Faivre, Laurence; Rivière, Jean-Baptiste

    2014-07-01

    Epileptic encephalopathy (EE) refers to a clinically and genetically heterogeneous group of severe disorders characterized by seizures, abnormal interictal electro-encephalogram, psychomotor delay, and/or cognitive deterioration. We ascertained two multiplex families (including one consanguineous family) consistent with an autosomal-recessive inheritance pattern of EE. All seven affected individuals developed subclinical seizures as early as the first day of life, severe epileptic disease, and profound developmental delay with no facial dysmorphism. Given the similarity in clinical presentation in the two families, we hypothesized that the observed phenotype was due to mutations in the same gene, and we performed exome sequencing in three affected individuals. Analysis of rare variants in genes consistent with an autosomal-recessive mode of inheritance led to identification of mutations in SLC13A5, which encodes the cytoplasmic sodium-dependent citrate carrier, notably expressed in neurons. Disease association was confirmed by cosegregation analysis in additional family members. Screening of 68 additional unrelated individuals with early-onset epileptic encephalopathy for SLC13A5 mutations led to identification of one additional subject with compound heterozygous mutations of SLC13A5 and a similar clinical presentation as the index subjects. Mutations affected key residues for sodium binding, which is critical for citrate transport. These findings underline the value of careful clinical characterization for genetic investigations in highly heterogeneous conditions such as EE and further highlight the role of citrate metabolism in epilepsy.

  12. Biallelic truncating mutations in FMN2, encoding the actin-regulatory protein Formin 2, cause nonsyndromic autosomal-recessive intellectual disability.

    PubMed

    Law, Rosalind; Dixon-Salazar, Tracy; Jerber, Julie; Cai, Na; Abbasi, Ansar A; Zaki, Maha S; Mittal, Kirti; Gabriel, Stacey B; Rafiq, Muhammad Arshad; Khan, Valeed; Nguyen, Maria; Ali, Ghazanfar; Copeland, Brett; Scott, Eric; Vasli, Nasim; Mikhailov, Anna; Khan, Muhammad Nasim; Andrade, Danielle M; Ayaz, Muhammad; Ansar, Muhammad; Ayub, Muhammad; Vincent, John B; Gleeson, Joseph G

    2014-12-01

    Dendritic spines represent the major site of neuronal activity in the brain; they serve as the receiving point for neurotransmitters and undergo rapid activity-dependent morphological changes that correlate with learning and memory. Using a combination of homozygosity mapping and next-generation sequencing in two consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability, we identified truncating mutations in formin 2 (FMN2), encoding a protein that belongs to the formin family of actin cytoskeleton nucleation factors and is highly expressed in the maturing brain. We found that FMN2 localizes to punctae along dendrites and that germline inactivation of mouse Fmn2 resulted in animals with decreased spine density; such mice were previously demonstrated to have a conditioned fear-learning defect. Furthermore, patient neural cells derived from induced pluripotent stem cells showed correlated decreased synaptic density. Thus, FMN2 mutations link intellectual disability either directly or indirectly to the regulation of actin-mediated synaptic spine density.

  13. Mutations in the Mitochondrial Methionyl-tRNA Synthetase Cause a Neurodegenerative Phenotype in Flies and a Recessive Ataxia (ARSAL) in Humans

    PubMed Central

    Jaiswal, Manish; Tétreault, Martine; Donti, Taraka; Sasarman, Florin; Bernard, Geneviève; Demers-Lamarche, Julie; Dicaire, Marie-Josée; Mathieu, Jean; Vanasse, Michel; Bouchard, Jean-Pierre; Rioux, Marie-France; Lourenco, Charles M.; Li, Zhihong; Haueter, Claire; Shoubridge, Eric A.; Graham, Brett H.; Brais, Bernard; Bellen, Hugo J.

    2012-01-01

    An increasing number of genes required for mitochondrial biogenesis, dynamics, or function have been found to be mutated in metabolic disorders and neurological diseases such as Leigh Syndrome. In a forward genetic screen to identify genes required for neuronal function and survival in Drosophila photoreceptor neurons, we have identified mutations in the mitochondrial methionyl-tRNA synthetase, Aats-met, the homologue of human MARS2. The fly mutants exhibit age-dependent degeneration of photoreceptors, shortened lifespan, and reduced cell proliferation in epithelial tissues. We further observed that these mutants display defects in oxidative phosphorylation, increased Reactive Oxygen Species (ROS), and an upregulated mitochondrial Unfolded Protein Response. With the aid of this knowledge, we identified MARS2 to be mutated in Autosomal Recessive Spastic Ataxia with Leukoencephalopathy (ARSAL) patients. We uncovered complex rearrangements in the MARS2 gene in all ARSAL patients. Analysis of patient cells revealed decreased levels of MARS2 protein and a reduced rate of mitochondrial protein synthesis. Patient cells also exhibited reduced Complex I activity, increased ROS, and a slower cell proliferation rate, similar to Drosophila Aats-met mutants. PMID:22448145

  14. Recessive truncating titin gene, TTN, mutations presenting as centronuclear myopathy

    PubMed Central

    Ceyhan-Birsoy, Ozge; Agrawal, Pankaj B.; Hidalgo, Carlos; Schmitz-Abe, Klaus; DeChene, Elizabeth T.; Swanson, Lindsay C.; Soemedi, Rachel; Vasli, Nasim; Iannaccone, Susan T.; Shieh, Perry B.; Shur, Natasha; Dennison, Jane M.; Lawlor, Michael W.; Laporte, Jocelyn; Markianos, Kyriacos; Fairbrother, William G.; Granzier, Henk

    2013-01-01

    Objective: To identify causative genes for centronuclear myopathies (CNM), a heterogeneous group of rare inherited muscle disorders that often present in infancy or early life with weakness and hypotonia, using next-generation sequencing of whole exomes and genomes. Methods: Whole-exome or -genome sequencing was performed in a cohort of 29 unrelated patients with clinicopathologic diagnoses of CNM or related myopathy depleted for cases with mutations of MTM1, DNM2, and BIN1. Immunofluorescence analyses on muscle biopsies, splicing assays, and gel electrophoresis of patient muscle proteins were performed to determine the molecular consequences of mutations of interest. Results: Autosomal recessive compound heterozygous truncating mutations of the titin gene, TTN, were identified in 5 individuals. Biochemical analyses demonstrated increased titin degradation and truncated titin proteins in patient muscles, establishing the impact of the mutations. Conclusions: Our study identifies truncating TTN mutations as a cause of congenital myopathy that is reported as CNM. Unlike the classic CNM genes that are all involved in excitation-contraction coupling at the triad, TTN encodes the giant sarcomeric protein titin, which forms a myofibrillar backbone for the components of the contractile machinery. This study expands the phenotypic spectrum associated with TTN mutations and indicates that TTN mutation analysis should be considered in cases of possible CNM without mutations in the classic CNM genes. PMID:23975875

  15. Mutations in UNC80, Encoding Part of the UNC79-UNC80-NALCN Channel Complex, Cause Autosomal-Recessive Severe Infantile Encephalopathy

    PubMed Central

    Shamseldin, Hanan E.; Faqeih, Eissa; Alasmari, Ali; Zaki, Maha S.; Gleeson, Joseph G.; Alkuraya, Fowzan S.

    2016-01-01

    Brain channelopathies represent a growing class of brain disorders that usually result in paroxysmal disorders, although their role in other neurological phenotypes, including the recently described NALCN-related infantile encephalopathy, is increasingly recognized. In three Saudi Arabian families and one Egyptian family all affected by a remarkably similar phenotype (infantile encephalopathy and largely normal brain MRI) to that of NALCN-related infantile encephalopathy, we identified a locus on 2q34 in which whole-exome sequencing revealed three, including two apparently loss-of-function, recessive mutations in UNC80. UNC80 encodes a large protein that is necessary for the stability and function of NALCN and for bridging NALCN to UNC79 to form a functional complex. Our results expand the clinical relevance of the UNC79-UNC80-NALCN channel complex. PMID:26708753

  16. Parkin gene causing benign autosomal recessive juvenile parkinsonism.

    PubMed

    Nisipeanu, P; Inzelberg, R; Abo Mouch, S; Carasso, R L; Blumen, S C; Zhang, J; Matsumine, H; Hattori, N; Mizuno, Y

    2001-06-12

    Autosomal recessive juvenile parkinsonism (AR-JP) is an early-onset parkinsonism caused by exonic deletions or point mutations in the parkingene. The relationship between the type of the genetic defect and the clinical presentation, the response to therapy, and the evolution have not been yet determined. The authors describe a single-basepair deletion at nucleotide 202 in exon 2 of the parkin gene in a kindred with a benign clinical course. PMID:11402119

  17. Recessive mutations in the INS gene result in neonatal diabetes through reduced insulin biosynthesis

    PubMed Central

    Garin, Intza; Edghill, Emma L.; Akerman, Ildem; Rubio-Cabezas, Oscar; Rica, Itxaso; Locke, Jonathan M.; Maestro, Miguel Angel; Alshaikh, Adnan; Bundak, Ruveyde; del Castillo, Gabriel; Deeb, Asma; Deiss, Dorothee; Fernandez, Juan M.; Godbole, Koumudi; Hussain, Khalid; O’Connell, Michele; Klupa, Thomasz; Kolouskova, Stanislava; Mohsin, Fauzia; Perlman, Kusiel; Sumnik, Zdenek; Rial, Jose M.; Ugarte, Estibaliz; Vasanthi, Thiruvengadam; Johnstone, Karen; Flanagan, Sarah E.; Martínez, Rosa; Castaño, Carlos; Patch, Ann-Marie; Fernández-Rebollo, Eduardo; Raile, Klemens; Morgan, Noel; Harries, Lorna W.; Castaño, Luis; Ellard, Sian; Ferrer, Jorge; de Nanclares, Guiomar Perez; Hattersley, Andrew T.

    2010-01-01

    Heterozygous coding mutations in the INS gene that encodes preproinsulin were recently shown to be an important cause of permanent neonatal diabetes. These dominantly acting mutations prevent normal folding of proinsulin, which leads to beta-cell death through endoplasmic reticulum stress and apoptosis. We now report 10 different recessive INS mutations in 15 probands with neonatal diabetes. Functional studies showed that recessive mutations resulted in diabetes because of decreased insulin biosynthesis through distinct mechanisms, including gene deletion, lack of the translation initiation signal, and altered mRNA stability because of the disruption of a polyadenylation signal. A subset of recessive mutations caused abnormal INS transcription, including the deletion of the C1 and E1 cis regulatory elements, or three different single base-pair substitutions in a CC dinucleotide sequence located between E1 and A1 elements. In keeping with an earlier and more severe beta-cell defect, patients with recessive INS mutations had a lower birth weight (−3.2 SD score vs. −2.0 SD score) and were diagnosed earlier (median 1 week vs. 10 weeks) compared to those with dominant INS mutations. Mutations in the insulin gene can therefore result in neonatal diabetes as a result of two contrasting pathogenic mechanisms. Moreover, the recessively inherited mutations provide a genetic demonstration of the essential role of multiple sequence elements that regulate the biosynthesis of insulin in man. PMID:20133622

  18. Autosomal-Recessive Intellectual Disability with Cerebellar Atrophy Syndrome Caused by Mutation of the Manganese and Zinc Transporter Gene SLC39A8.

    PubMed

    Boycott, Kym M; Beaulieu, Chandree L; Kernohan, Kristin D; Gebril, Ola H; Mhanni, Aziz; Chudley, Albert E; Redl, David; Qin, Wen; Hampson, Sarah; Küry, Sébastien; Tetreault, Martine; Puffenberger, Erik G; Scott, James N; Bezieau, Stéphane; Reis, André; Uebe, Steffen; Schumacher, Johannes; Hegele, Robert A; McLeod, D Ross; Gálvez-Peralta, Marina; Majewski, Jacek; Ramaekers, Vincent T; Nebert, Daniel W; Innes, A Micheil; Parboosingh, Jillian S; Abou Jamra, Rami

    2015-12-01

    Manganese (Mn) and zinc (Zn) are essential divalent cations used by cells as protein cofactors; various human studies and animal models have demonstrated the importance of Mn and Zn for development. Here we describe an autosomal-recessive disorder in six individuals from the Hutterite community and in an unrelated Egyptian sibpair; the disorder is characterized by intellectual disability, developmental delay, hypotonia, strabismus, cerebellar atrophy, and variable short stature. Exome sequencing in one affected Hutterite individual and the Egyptian family identified the same homozygous variant, c.112G>C (p.Gly38Arg), affecting a conserved residue of SLC39A8. The affected Hutterite and Egyptian individuals did not share an extended common haplotype, suggesting that the mutation arose independently. SLC39A8 is a member of the solute carrier gene family known to import Mn, Zn, and other divalent cations across the plasma membrane. Evaluation of these two metal ions in the affected individuals revealed variably low levels of Mn and Zn in blood and elevated levels in urine, indicating renal wasting. Our findings identify a human Mn and Zn transporter deficiency syndrome linked to SLC39A8, providing insight into the roles of Mn and Zn homeostasis in human health and development.

  19. Autosomal-Recessive Intellectual Disability with Cerebellar Atrophy Syndrome Caused by Mutation of the Manganese and Zinc Transporter Gene SLC39A8

    PubMed Central

    Boycott, Kym M.; Beaulieu, Chandree L.; Kernohan, Kristin D.; Gebril, Ola H.; Mhanni, Aziz; Chudley, Albert E.; Redl, David; Qin, Wen; Hampson, Sarah; Küry, Sébastien; Tetreault, Martine; Puffenberger, Erik G.; Scott, James N.; Bezieau, Stéphane; Reis, André; Uebe, Steffen; Schumacher, Johannes; Hegele, Robert A.; McLeod, D. Ross; Gálvez-Peralta, Marina; Majewski, Jacek; Ramaekers, Vincent T.; Nebert, Daniel W.; Innes, A. Micheil; Parboosingh, Jillian S.; Abou Jamra, Rami

    2015-01-01

    Manganese (Mn) and zinc (Zn) are essential divalent cations used by cells as protein cofactors; various human studies and animal models have demonstrated the importance of Mn and Zn for development. Here we describe an autosomal-recessive disorder in six individuals from the Hutterite community and in an unrelated Egyptian sibpair; the disorder is characterized by intellectual disability, developmental delay, hypotonia, strabismus, cerebellar atrophy, and variable short stature. Exome sequencing in one affected Hutterite individual and the Egyptian family identified the same homozygous variant, c.112G>C (p.Gly38Arg), affecting a conserved residue of SLC39A8. The affected Hutterite and Egyptian individuals did not share an extended common haplotype, suggesting that the mutation arose independently. SLC39A8 is a member of the solute carrier gene family known to import Mn, Zn, and other divalent cations across the plasma membrane. Evaluation of these two metal ions in the affected individuals revealed variably low levels of Mn and Zn in blood and elevated levels in urine, indicating renal wasting. Our findings identify a human Mn and Zn transporter deficiency syndrome linked to SLC39A8, providing insight into the roles of Mn and Zn homeostasis in human health and development. PMID:26637978

  20. Autosomal-Recessive Intellectual Disability with Cerebellar Atrophy Syndrome Caused by Mutation of the Manganese and Zinc Transporter Gene SLC39A8.

    PubMed

    Boycott, Kym M; Beaulieu, Chandree L; Kernohan, Kristin D; Gebril, Ola H; Mhanni, Aziz; Chudley, Albert E; Redl, David; Qin, Wen; Hampson, Sarah; Küry, Sébastien; Tetreault, Martine; Puffenberger, Erik G; Scott, James N; Bezieau, Stéphane; Reis, André; Uebe, Steffen; Schumacher, Johannes; Hegele, Robert A; McLeod, D Ross; Gálvez-Peralta, Marina; Majewski, Jacek; Ramaekers, Vincent T; Nebert, Daniel W; Innes, A Micheil; Parboosingh, Jillian S; Abou Jamra, Rami

    2015-12-01

    Manganese (Mn) and zinc (Zn) are essential divalent cations used by cells as protein cofactors; various human studies and animal models have demonstrated the importance of Mn and Zn for development. Here we describe an autosomal-recessive disorder in six individuals from the Hutterite community and in an unrelated Egyptian sibpair; the disorder is characterized by intellectual disability, developmental delay, hypotonia, strabismus, cerebellar atrophy, and variable short stature. Exome sequencing in one affected Hutterite individual and the Egyptian family identified the same homozygous variant, c.112G>C (p.Gly38Arg), affecting a conserved residue of SLC39A8. The affected Hutterite and Egyptian individuals did not share an extended common haplotype, suggesting that the mutation arose independently. SLC39A8 is a member of the solute carrier gene family known to import Mn, Zn, and other divalent cations across the plasma membrane. Evaluation of these two metal ions in the affected individuals revealed variably low levels of Mn and Zn in blood and elevated levels in urine, indicating renal wasting. Our findings identify a human Mn and Zn transporter deficiency syndrome linked to SLC39A8, providing insight into the roles of Mn and Zn homeostasis in human health and development. PMID:26637978

  1. X-linked recessive atrophic macular degeneration from RPGR mutation.

    PubMed

    Ayyagari, Radha; Demirci, F Yesim; Liu, Jiafan; Bingham, Eve L; Stringham, Heather; Kakuk, Laura E; Boehnke, Michael; Gorin, Michael B; Richards, Julia E; Sieving, Paul A

    2002-08-01

    We mapped a new X-linked recessive atrophic macular degeneration locus to Xp21.1-p11.4 and show allelic involvement of the gene RPGR, which normally causes severe peripheral retinal degeneration leading to global blindness. Ten affected males whom we examined had primarily macular atrophy causing progressive loss of visual acuity with minimal peripheral visual impairment. One additional male showed extensive macular degeneration plus peripheral loss of retinal pigment epithelium and choriocapillaries. Full-field electroretinograms (ERGs) showed normal cone and rod responses in some affected males despite advanced macular degeneration, emphasizing the dissociation of atrophic macular degeneration from generalized cone degenerations, including X-linked cone dystrophy (COD1). The RPGR gene nonsense mutation G-->T at open reading frame (ORF)15+1164 cosegregated with the disease and may create a donor splice site. Identification of an RPGR mutation in atrophic maculardegeneration expands the phenotypic range associated with this gene and provides a new tool for the dissection of the relationship between clinically different retinal pathologies.

  2. Mineralocorticoid Receptor Mutations and a Severe Recessive Pseudohypoaldosteronism Type 1

    PubMed Central

    Hubert, Edwige-Ludiwyne; Teissier, Raphaël; Fernandes-Rosa, Fábio L.; Fay, Michel; Rafestin-Oblin, Marie-Edith; Jeunemaitre, Xavier; Metz, Chantal; Escoubet, Brigitte

    2011-01-01

    Pseudohypoaldosteronism type 1 (PHA1) is a rare genetic disease of mineralocorticoid resistance characterized by salt wasting and failure to thrive in infancy. Here we describe the first case of a newborn with severe recessive PHA1 caused by two heterozygous mutations in NR3C2, gene coding for the mineralocorticoid receptor (MR). Independent segregation of the mutations occurred in the family, with p.Ser166X being transmitted from the affected father and p.Trp806X from the asymptomatic mother Whereas the truncated MR166X protein was degraded, MR806X was expressed both at the mRNA and protein level. Functional studies demonstrated that despite its inability to bind aldosterone, MR806X had partial ligand-independent transcriptional activity. Partial nuclear localization of MR806X in the absence of hormone was identified as a prerequisite to initiate transcription. This exceptional case broadens the spectrum of clinical phenotypes of PHA1 and demonstrates that minimal residual activity of MR is compatible with life. It also suggests that rare hypomorphic NR3C2 alleles may be more common than expected from the prevalence of detected PHA1 cases. This might prove relevant for patient's care in neonatal salt losing disorders and may affect renal salt handling and blood pressure in the general population. PMID:21903996

  3. Recessive TRAPPC11 mutations cause a disease spectrum of limb girdle muscular dystrophy and myopathy with movement disorder and intellectual disability.

    PubMed

    Bögershausen, Nina; Shahrzad, Nassim; Chong, Jessica X; von Kleist-Retzow, Jürgen-Christoph; Stanga, Daniela; Li, Yun; Bernier, Francois P; Loucks, Catrina M; Wirth, Radu; Puffenberger, Eric G; Hegele, Robert A; Schreml, Julia; Lapointe, Gabriel; Keupp, Katharina; Brett, Christopher L; Anderson, Rebecca; Hahn, Andreas; Innes, A Micheil; Suchowersky, Oksana; Mets, Marilyn B; Nürnberg, Gudrun; McLeod, D Ross; Thiele, Holger; Waggoner, Darrel; Altmüller, Janine; Boycott, Kym M; Schoser, Benedikt; Nürnberg, Peter; Ober, Carole; Heller, Raoul; Parboosingh, Jillian S; Wollnik, Bernd; Sacher, Michael; Lamont, Ryan E

    2013-07-11

    Myopathies are a clinically and etiologically heterogeneous group of disorders that can range from limb girdle muscular dystrophy (LGMD) to syndromic forms with associated features including intellectual disability. Here, we report the identification of mutations in transport protein particle complex 11 (TRAPPC11) in three individuals of a consanguineous Syrian family presenting with LGMD and in five individuals of Hutterite descent presenting with myopathy, infantile hyperkinetic movements, ataxia, and intellectual disability. By using a combination of whole-exome or genome sequencing with homozygosity mapping, we identified the homozygous c.2938G>A (p.Gly980Arg) missense mutation within the gryzun domain of TRAPPC11 in the Syrian LGMD family and the homozygous c.1287+5G>A splice-site mutation resulting in a 58 amino acid in-frame deletion (p.Ala372_Ser429del) in the foie gras domain of TRAPPC11 in the Hutterite families. TRAPPC11 encodes a component of the multiprotein TRAPP complex involved in membrane trafficking. We demonstrate that both mutations impair the binding ability of TRAPPC11 to other TRAPP complex components and disrupt the Golgi apparatus architecture. Marker trafficking experiments for the p.Ala372_Ser429del deletion indicated normal ER-to-Golgi trafficking but dramatically delayed exit from the Golgi to the cell surface. Moreover, we observed alterations of the lysosomal membrane glycoproteins lysosome-associated membrane protein 1 (LAMP1) and LAMP2 as a consequence of TRAPPC11 dysfunction supporting a defect in the transport of secretory proteins as the underlying pathomechanism.

  4. Recessive TRAPPC11 Mutations Cause a Disease Spectrum of Limb Girdle Muscular Dystrophy and Myopathy with Movement Disorder and Intellectual Disability

    PubMed Central

    Bögershausen, Nina; Shahrzad, Nassim; Chong, Jessica X.; von Kleist-Retzow, Jürgen-Christoph; Stanga, Daniela; Li, Yun; Bernier, Francois P.; Loucks, Catrina M.; Wirth, Radu; Puffenberger, Eric G.; Hegele, Robert A.; Schreml, Julia; Lapointe, Gabriel; Keupp, Katharina; Brett, Christopher L.; Anderson, Rebecca; Hahn, Andreas; Innes, A. Micheil; Suchowersky, Oksana; Mets, Marilyn B.; Nürnberg, Gudrun; McLeod, D. Ross; Thiele, Holger; Waggoner, Darrel; Altmüller, Janine; Boycott, Kym M.; Schoser, Benedikt; Nürnberg, Peter; Ober, Carole; Heller, Raoul; Parboosingh, Jillian S.; Wollnik, Bernd; Sacher, Michael; Lamont, Ryan E.

    2013-01-01

    Myopathies are a clinically and etiologically heterogeneous group of disorders that can range from limb girdle muscular dystrophy (LGMD) to syndromic forms with associated features including intellectual disability. Here, we report the identification of mutations in transport protein particle complex 11 (TRAPPC11) in three individuals of a consanguineous Syrian family presenting with LGMD and in five individuals of Hutterite descent presenting with myopathy, infantile hyperkinetic movements, ataxia, and intellectual disability. By using a combination of whole-exome or genome sequencing with homozygosity mapping, we identified the homozygous c.2938G>A (p.Gly980Arg) missense mutation within the gryzun domain of TRAPPC11 in the Syrian LGMD family and the homozygous c.1287+5G>A splice-site mutation resulting in a 58 amino acid in-frame deletion (p.Ala372_Ser429del) in the foie gras domain of TRAPPC11 in the Hutterite families. TRAPPC11 encodes a component of the multiprotein TRAPP complex involved in membrane trafficking. We demonstrate that both mutations impair the binding ability of TRAPPC11 to other TRAPP complex components and disrupt the Golgi apparatus architecture. Marker trafficking experiments for the p.Ala372_Ser429del deletion indicated normal ER-to-Golgi trafficking but dramatically delayed exit from the Golgi to the cell surface. Moreover, we observed alterations of the lysosomal membrane glycoproteins lysosome-associated membrane protein 1 (LAMP1) and LAMP2 as a consequence of TRAPPC11 dysfunction supporting a defect in the transport of secretory proteins as the underlying pathomechanism. PMID:23830518

  5. Mutational founder effect in recessive dystrophic epidermolysis bullosa families from Southern Tunisia.

    PubMed

    Ben Brick, Ahlem Sabrine; Laroussi, Nadia; Mesrati, Hela; Kefi, Rym; Bchetnia, Mbarka; Lasram, Khaled; Ben Halim, Nizar; Romdhane, Lilia; Ouragini, Houyem; Marrakchi, Salaheddine; Boubaker, Mohamed Samir; Meddeb Cherif, Mounira; Castiglia, Daniele; Hovnanian, Alain; Abdelhak, Sonia; Turki, Hamida

    2014-05-01

    Dystrophic epidermolysis bullosa (DEB) is a group of heritable bullous skin disorders caused by mutations in the COL7A1 gene. One of the most severe forms of DEB is the severe generalized [recessive dystrophic epidermolysis bullosa (RDEB-SG)] subtype, which is inherited in an autosomal recessive manner. This subtype is most often due to COL7A1 mutations resulting in a premature termination codon on both alleles. We report here, the molecular investigation of 15 patients belonging to 14 nuclear families from the city of Sfax in Southern Tunisia, with clinical features of RDEB-SG complicated by squamous cell carcinoma in 3 patients. We identified two novel mutations, p.Val769LeufsX1 and p.Ala2297SerfsX91, in addition to one previously reported mutation (p.Arg2063Trp). The p.Val769LeufsX1 mutation was shared by 11 families and haplotype analysis indicated that it is a founder mutation. The p.Ala2297SerfsX91 mutation was a private mutation found in only one family. Together with the previously described recurrent mutations in Tunisia, screening for the founder p.Val769LeufsX1 mutation should provide a rapid molecular diagnosis tool for mutation screening in RDEB patients from Southern Tunisia and possibly from other Mediterranean populations sharing the same genetic background.

  6. Recessive axonal Charcot-Marie-Tooth disease due to compound heterozygous mitofusin 2 mutations

    PubMed Central

    Polke, J.M.; Laurá, M.; Pareyson, D.; Taroni, F.; Milani, M.; Bergamin, G.; Gibbons, V.S.; Houlden, H.; Chamley, S.C.; Blake, J.; DeVile, C.; Sandford, R.; Sweeney, M.G.; Davis, M.B.

    2011-01-01

    Objective: Mutations in mitofusin 2 (MFN2) are the most common cause of axonal Charcot-Marie-Tooth disease (CMT2). Over 50 mutations have been reported, mainly causing autosomal dominant disease, though families with homozygous or compound heterozygous mutations have been described. We present 3 families with early-onset CMT2 associated with compound heterozygous MFN2 mutations. Transcriptional analysis was performed to investigate the effects of the mutations. Methods: Patients were examined clinically and electrophysiologically; parents were also examined where available. Genetic investigations included MFN2 DNA sequencing and dosage analysis by multiplex ligation-dependent probe amplification. MFN2 mRNA transcripts from blood lymphocytes were analyzed in 2 families. Results: Compound heterozygosity for MFN2 mutations was associated with early-onset CMT2 of varying severity between pedigrees. Parents, where examined, were unaffected and were heterozygous for the expected mutations. Four novel mutations were detected (one missense, one nonsense, an intragenic deletion of exons 7 + 8, and a 3–base pair deletion), as well as 2 previously reported missense mutations. Transcriptional analysis demonstrated aberrant splicing of the exonic deletion and indicated nonsense-mediated decay of mutant alleles with premature truncating mutations. Conclusions: Our findings confirm that MFN2 mutations can cause early-onset CMT2 with apparent recessive inheritance. Novel genetic findings include an intragenic MFN2 deletion and nonsense-mediated decay. Carrier parents were asymptomatic, suggesting that MFN2 null alleles can be nonpathogenic unless coinherited with another mutation. PMID:21715711

  7. Mutations of the tyrosinase gene produce autosomal recessive ocular albinism

    SciTech Connect

    King, R.A.; Summers, C.G.; Oetting, W.S.

    1994-09-01

    Albinism has historically been divided into ocular (OA) and oculocutaneous (OCA) types based on the presence or absence of clinically apparent skin and hair involvement in an individual with the ocular features of albinism. The major genes for OCA include the tyrosinase gene in OCA1 and the P gene in OCA2. X-linked and autosomal recessive OA have been described and the responsible genes have not been identified. We now present six Caucasian individuals who have the phenotype of autosomal recessive OA but who have OCA1 as shown by the presence of mutations of the tyrosinase. They had white or very light hair and white skin at birth, and cutaneous pigment developed in the first decade of life. At ages ranging from 1.5-23 years, hair color was dark blond to light brown. The skin had generalized pigment and well developed tan was present on the exposed arm and face skin of four. Iris pigment was present and iris translucency varied. Molecular analysis of the tyrosinase gene, using PCR amplification and direct di-deoxy sequencing showed the following mutations: E398Z/E398Q, P406S/g346a, R402E/T373K, ?/D383N, and H211N/T373K. The homozygous individual was not from a known consanguineous mating. T373K is the most common tyrosinase gene mutation in our laboratory. Three of these mutations are associated with a total loss of tyrosinase activity (g346a splice-site, T373K, and D383N), while four are associated with residual enzyme activity (H211N, R402E, E398Q, and P406S). These studies show that mutations of the tyrosinase gene can produce the phenotype of autosomal recessive OA in an individual who has normal amounts of cutaneous pigment and the ability to tan after birth. This extends the phenotypic range of OCA1 to normal cutaneous pigment after early childhood, and suggest that mutations of the tyrosinase gene account for a significant number of individuals with autosomal recessive OA.

  8. The fate of 12 recessive mutations in a single village.

    PubMed

    Zlotogora, J; Hujerat, Y; Barges, S; Shalev, S A; Chakravarti, A

    2007-03-01

    In a Muslim Arab village, relatively isolated because of the preference of consanguineous marriages, we studied the fate of 12 mutations in 5 different genes. The study was based on carriers detected among relatives of affected patients and of carriers discovered in a random sample of 424 adults. Most of the mutations have been introduced by a carrier(s) originating from another village, but a few have been de novo events. Mutations that are very frequent in the entire village were introduced soon after the foundation of the village. Examples of such mutations are [GBJ2, 35Gdel] and [MEFV, M680I], with a carrier frequency of 7.8% and 6.2%, respectively. Many of the other mutations that are rare were introduced recently into the village and are frequent only among the descendants of the first couple carrying the mutation. For instance all the carriers of [ARSA, Q190H], responsible for metachromatic leukodystrophy, were found among the 218 descendants of a couple who were living in the village 4 generations ago. Since the village is typical for the region this study allows for some general conclusions to be drawn. In a population with a high degree of inbreeding the diagnosis of a single family with a patient(s) affected with a recessive disorder points to a recent event, while the finding of a rare disease in several families from an inbred population points to an older mutation. Mutations are often "exported" from one population to another by marriage. In the new inbred population this novel mutation will either be lost or will become frequent as the result of a founder effect. These observations are important for genetic counselling in the case of a recent mutation, since only the descendants of the founder couple are at risk, while in the case of older mutations the risk may be for the entire village. In the case of those frequent ancient mutations, the risk for a relative of an affected individual will be similar whether he marries a close relative or any random

  9. Pathophysiological mechanisms of dominant and recessive GLRA1 mutations in hyperekplexia.

    PubMed

    Chung, Seo-Kyung; Vanbellinghen, Jean-François; Mullins, Jonathan G L; Robinson, Angela; Hantke, Janina; Hammond, Carrie L; Gilbert, Daniel F; Freilinger, Michael; Ryan, Monique; Kruer, Michael C; Masri, Amira; Gurses, Candan; Ferrie, Colin; Harvey, Kirsten; Shiang, Rita; Christodoulou, John; Andermann, Frederick; Andermann, Eva; Thomas, Rhys H; Harvey, Robert J; Lynch, Joseph W; Rees, Mark I

    2010-07-14

    Hyperekplexia is a rare, but potentially fatal, neuromotor disorder characterized by exaggerated startle reflexes and hypertonia in response to sudden, unexpected auditory or tactile stimuli. This disorder is primarily caused by inherited mutations in the genes encoding the glycine receptor (GlyR) alpha1 subunit (GLRA1) and the presynaptic glycine transporter GlyT2 (SLC6A5). In this study, systematic DNA sequencing of GLRA1 in 88 new unrelated human hyperekplexia patients revealed 19 sequence variants in 30 index cases, of which 21 cases were inherited in recessive or compound heterozygote modes. This indicates that recessive hyperekplexia is far more prevalent than previous estimates. From the 19 GLRA1 sequence variants, we have investigated the functional effects of 11 novel and 2 recurrent mutations. The expression levels and functional properties of these hyperekplexia mutants were analyzed using a high-content imaging system and patch-clamp electrophysiology. When expressed in HEK293 cells, either as homomeric alpha1 or heteromeric alpha1beta GlyRs, subcellular localization defects were the major mechanism underlying recessive mutations. However, mutants without trafficking defects typically showed alterations in the glycine sensitivity suggestive of disrupted receptor function. This study also reports the first hyperekplexia mutation associated with a GlyR leak conductance, suggesting tonic channel opening as a new mechanism in neuronal ligand-gated ion channels. PMID:20631190

  10. Adult-onset autosomal recessive ataxia associated with neuronal ceroid lipofuscinosis type 5 gene (CLN5) mutations.

    PubMed

    Mancini, Cecilia; Nassani, Stefano; Guo, Yiran; Chen, Yulan; Giorgio, Elisa; Brussino, Alessandro; Di Gregorio, Eleonora; Cavalieri, Simona; Lo Buono, Nicola; Funaro, Ada; Pizio, Nicola Renato; Nmezi, Bruce; Kyttala, Aija; Santorelli, Filippo Maria; Padiath, Quasar Salem; Hakonarson, Hakon; Zhang, Hao; Brusco, Alfredo

    2015-01-01

    Autosomal recessive inherited ataxias are a growing group of genetic disorders. We report two Italian siblings presenting in their mid-50s with difficulty in walking, dysarthria and progressive cognitive decline. Visual loss, ascribed to glaucoma, manifested a few years before the other symptoms. Brain MRI showed severe cerebellar atrophy, prevalent in the vermis, with marked cortical atrophy of both hemispheres. Exome sequencing identified a novel homozygous mutation (c.935G > A;p.Ser312Asn) in the ceroid neuronal lipofuscinosis type 5 gene (CLN5). Bioinformatics predictions and in vitro studies showed that the mutation was deleterious and likely affects ER-lysosome protein trafficking. Our findings support CLN5 hypomorphic mutations cause autosomal recessive cerebellar ataxia, confirming other reports showing CLN mutations are associated with adult-onset neurodegenerative disorders. We suggest CLN genes should be considered in the molecular analyses of patients presenting with adult-onset autosomal recessive cerebellar ataxia.

  11. A novel frameshift mutation of DDHD1 in a Japanese patient with autosomal recessive spastic paraplegia.

    PubMed

    Miura, Shiroh; Morikawa, Takuya; Fujioka, Ryuta; Kosaka, Kengo; Yamada, Kohei; Hattori, Gohsuke; Motomura, Manabu; Taniwaki, Takayuki; Shibata, Hiroki

    2016-08-01

    Spastic paraplegia (SPG) type 28 is an autosomal recessive SPG caused by mutations in the DDHD1 gene. We examined a Japanese 54-years-old male patient with autosomal recessive SPG. His parents were consanguineous. He needed a wheelchair for transfer due to spastic paraplegia. There was a history of operations for bilateral hallux valgus, thoracic ossification of the yellow ligament, bilateral carpal tunnel syndrome, bilateral ankle contracture, and lumbar spinal canal stenosis. He noticed gait disturbance at age 14. He used a cane for walking in his 40s. On neurological examination, he showed hyperreflexia, spasticity, and weakness in the lower extremities and bilateral Babinski reflexes. Urinary dysfunctions and impaired vibration sense in the lower limbs were observed. By exome sequencing analysis using Agilent SureSelect and Illumina MiSeq, we identified 17,248 homozygous nucleotide variants in the patient. Through the examination of 48 candidate genes known to be responsible for autosomal recessive SPG, we identified a novel homozygous 4-bp deletion, c.914_917delGTAA, p.Ser305Ilefs*2 in exon2 of the DDHD1 gene encoding phosphatidic acid-preferring phospholipase A1 (PA-PLA1). The mutation is expected to cause a frameshift generating a premature stop codon 3-bp downstream from the deletion. In consequence, the DDHD domain that is known to be critical for PLA1 activity is completely depleted in the mutated DDHD1 protein, predicted to be a functionally null mutation of the DDHD1 gene. By Sanger sequencing, we confirmed that both parents are heterozygous for the mutation. This variation was not detected in 474 Japanese control subjects as well as the data of the 1,000G Project. We conclude that the novel mutation in DDHD1 is the causative variant for the SPG28 patient that is the first record of the disease in Japanese population. PMID:27216551

  12. 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

  13. 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

  14. Homozygous MYH7 R1820W mutation results in recessive myosin storage myopathy: scapuloperoneal and respiratory weakness with dilated cardiomyopathy.

    PubMed

    Yüceyar, Nur; Ayhan, Özgecan; Karasoy, Hatice; Tolun, Aslıhan

    2015-04-01

    Myosin storage myopathy (MSM) is a protein aggregate myopathy caused by the accumulation of myosin in muscle fibres and results from MYH7 mutation. Although MYH7 mutation is also an established cause of variable cardiomyopathy with or without skeletal myopathy, cardiomyopathy with MSM is a rare combination. Here, we update the clinical findings in the two brothers that we previously reported as having recessively inherited MSM characterized by scapuloperoneal distribution of weakness and typical hyaline-like bodies in type 1 muscle fibres. One of the patients, weak from childhood but not severely symptomatic until 28 years of age, had an unusual combination of MSM, severe dilated cardiomyopathy, and respiratory impairment at the age of 44 years. We identified homozygous missense mutation c.5458C>T (p.R1820W) in exon 37 in these patients as the second recessive MYH7 mutation reported to date.

  15. Recessive and dominant mutations in retinoic acid receptor beta in cases with microphthalmia and diaphragmatic hernia.

    PubMed

    Srour, Myriam; Chitayat, David; Caron, Véronique; Chassaing, Nicolas; Bitoun, Pierre; Patry, Lysanne; Cordier, Marie-Pierre; Capo-Chichi, José-Mario; Francannet, Christine; Calvas, Patrick; Ragge, Nicola; Dobrzeniecka, Sylvia; Hamdan, Fadi F; Rouleau, Guy A; Tremblay, André; Michaud, Jacques L

    2013-10-01

    Anophthalmia and/or microphthalmia, pulmonary hypoplasia, diaphragmatic hernia, and cardiac defects are the main features of PDAC syndrome. Recessive mutations in STRA6, encoding a membrane receptor for the retinol-binding protein, have been identified in some cases with PDAC syndrome, although many cases have remained unexplained. Using whole-exome sequencing, we found that two PDAC-syndrome-affected siblings, but not their unaffected sibling, were compound heterozygous for nonsense (c.355C>T [p.Arg119(∗)]) and frameshift (c.1201_1202insCT [p.Ile403Serfs(∗)15]) mutations in retinoic acid receptor beta (RARB). Transfection studies showed that p.Arg119(∗) and p.Ile403Serfs(∗)15 altered RARB had no transcriptional activity in response to ligands, confirming that the mutations induced a loss of function. We then sequenced RARB in 15 subjects with anophthalmia and/or microphthalmia and at least one other feature of PDAC syndrome. Surprisingly, three unrelated subjects with microphthalmia and diaphragmatic hernia showed de novo missense mutations affecting the same codon; two of the subjects had the c.1159C>T (Arg387Cys) mutation, whereas the other one carried the c.1159C>A (p.Arg387Ser) mutation. We found that compared to the wild-type receptor, p.Arg387Ser and p.Arg387Cys altered RARB induced a 2- to 3-fold increase in transcriptional activity in response to retinoic acid ligands, suggesting a gain-of-function mechanism. Our study thus suggests that both recessive and dominant mutations in RARB cause anophthalmia and/or microphthalmia and diaphragmatic hernia, providing further evidence of the crucial role of the retinoic acid pathway during eye development and organogenesis.

  16. Panel-based NGS Reveals Novel Pathogenic Mutations in Autosomal Recessive Retinitis Pigmentosa.

    PubMed

    Perez-Carro, Raquel; Corton, Marta; Sánchez-Navarro, Iker; Zurita, Olga; Sanchez-Bolivar, Noelia; Sánchez-Alcudia, Rocío; Lelieveld, Stefan H; Aller, Elena; Lopez-Martinez, Miguel Angel; López-Molina, Ma Isabel; Fernandez-San Jose, Patricia; Blanco-Kelly, Fiona; Riveiro-Alvarez, Rosa; Gilissen, Christian; Millan, Jose M; Avila-Fernandez, Almudena; Ayuso, Carmen

    2016-01-25

    Retinitis pigmentosa (RP) is a group of inherited progressive retinal dystrophies (RD) characterized by photoreceptor degeneration. RP is highly heterogeneous both clinically and genetically, which complicates the identification of causative genes and mutations. Targeted next-generation sequencing (NGS) has been demonstrated to be an effective strategy for the detection of mutations in RP. In our study, an in-house gene panel comprising 75 known RP genes was used to analyze a cohort of 47 unrelated Spanish families pre-classified as autosomal recessive or isolated RP. Disease-causing mutations were found in 27 out of 47 cases achieving a mutation detection rate of 57.4%. In total, 33 pathogenic mutations were identified, 20 of which were novel mutations (60.6%). Furthermore, not only single nucleotide variations but also copy-number variations, including three large deletions in the USH2A and EYS genes, were identified. Finally seven out of 27 families, displaying mutations in the ABCA4, RP1, RP2 and USH2A genes, could be genetically or clinically reclassified. These results demonstrate the potential of our panel-based NGS strategy in RP diagnosis.

  17. The stability of mutator (MR)-induced X-chromosomal recessive visible mutations in Drosophila melanogaster.

    PubMed

    Eeken, J C

    1982-10-01

    In Drosophila, MR (male recombination) second chromosomes are known to act as mutators and recombination inducers in males. The induction of visible mutations by MR is observed at only a limited number of genes, such as singed bristle (sn), raspberry eye colour (ras), yellow body colour (y) and a carmine eye colour (car). Furthermore, sn mutations induced by MR are highly unstable, changing from a strong to a weak expression or reverting to the wild-type. It has been hypothesized by analogy with IS mutations in microorganisms, that MR-induced mutations also represent mutations of the insertion type. In this investigation the stability of two MR-h12-induced X-linked visible mutations was tested, one singed (snMR) and one raspberry (rasMR). The reversion frequency of both MR-induced mutations was low in the base population as well as upon outcrossing to C(1)DX, yw f females. The data reported here show that the MR-induced mutations become highly unstable when MR is re-introduced. The change of expression of an MR-induced mutation to a weaker phenotype or to the wild-type occurred at a frequency of 3.3 X 10(-3) (ras) to 20.4 X 10(-3) (sn). Recessive lethal mutations induced by MR in the X-chromosomes carrying the MR-induced singed or raspberry mutation were isolated and analysed. Among 11 independently MR-induced lethals in the rasMR-carrying X-chromosome, 4 were found to be allelic to a small deficiency that included the raspberry gene. 13 lethals were induced by MR in the snMR-carrying X-chromosome. Of these, 3 were located near the sn locus but none was allelic to a deficiency including the singed gene. PMID:6815525

  18. Comparative induction of somatic eye-color mutations and sex-linked recessive lethals in Drosophila melanogaster by tryptophan pyrolysates.

    PubMed

    Fujikawa, K; Inagaki, E; Uchibori, M; Kondo, S

    1983-12-01

    The mutagenicities of the products of pyrolysis of tryptophan, Trp-P-1 and Trp-P-2, on Drosophila melanogaster were examined by measuring the effects of these compounds in inducing recessive lethals and somatic eye-color mutations. Since negative results have already been obtained by the standard procedure in males, Trp-P-1 and Trp-P-2 (0.75 to 6 mg/ml) in sucrose solution were given to females for assay of recessive lethal mutations in X-chromosomes. These compounds caused a marginal increase above the control level in the mutation frequency. For the assay of effects on somatic eye-color mutations, Trp-P-1 (200 and 400 ppm) and Trp-P-2 (400 and 800 ppm) were fed to male larvae of a tester strain carrying a genetically unstable marker set of z and w+ on the X-chromosome. These compounds caused dose-dependent increases above the control level in somatic eye-color mutations in adults. It is concluded that, under the conditions used, the somatic eye-color mutation system was more sensitive than the recessive lethal system to the mutagenic effects of tryptophan pyrolysates. PMID:6419091

  19. Neuropathology of the recessive A673V APP mutation: Alzheimer disease with distinctive features.

    PubMed

    Giaccone, Giorgio; Morbin, Michela; Moda, Fabio; Botta, Mario; Mazzoleni, Giulia; Uggetti, Andrea; Catania, Marcella; Moro, Maria Luisa; Redaelli, Veronica; Spagnoli, Alberto; Rossi, Roberta Simona; Salmona, Mario; Di Fede, Giuseppe; Tagliavini, Fabrizio

    2010-12-01

    Mutations of three different genes, encoding β-amyloid precursor protein (APP), presenilin 1 and presenilin 2 are associated with familial Alzheimer's disease (AD). Recently, the APP mutation A673V has been identified that stands out from all the genetic defects previously reported in these three genes, since it causes the disease only in the homozygous state (Di Fede et al. in Science 323:1473-1477, 2009). We here provide the detailed neuropathological picture of the proband of this family, who was homozygous for the APP A673V mutation and recently came to death. The brain has been studied by histological and immunohistochemical techniques, at the optical and ultrastructural levels. Cerebral Aβ accumulation and tau pathology were severe and extensive. Peculiar features were the configuration of the Aβ deposits that were of large size, mostly perivascular and exhibited a close correspondence between the pattern elicited by amyloid stainings and the labeling obtained with immunoreagents specific for Aβ40 or Aβ42. Moreover, Aβ deposition spared the neostriatum while deeply affecting the cerebellum, and therefore was not in compliance with the hierarchical topographical sequence of involvement documented in sporadic AD. Therefore, the neuropathological picture of familial AD caused by the APP recessive mutation A673V presents distinctive characteristics compared to sporadic AD or familial AD inherited as a dominant trait. Main peculiar features are the morphology, structural properties and composition of the Aβ deposits as well as their topographic distribution in the brain.

  20. How many loci on the X-chromosome of Drosophila melanogaster can mutate to recessive lethals

    SciTech Connect

    Abrahamson, S.; Wuergler, F.E.; DeJongh, C.; Meyer, H.U.

    1980-01-01

    The sensitivity of the sex-linked recessive lethal test is due to the fact that a very large number of loci are included in the mutation study. From extensive studies on the spontaneous sex-linked recessive lethal frequency and spontaneous specific locus mutation rates, it is possible to derive an estimate of the number of loci included in the recessive lethal test. The average number derived from three estimates on male and female germ cells in 563 loci. A second independent approach derives from published data which analyzed short regions of the genome and the proportion of loci within these regions which mutate to lethality. This analysis suggests that 830 loci are potentially lethal mutables. We describe the reasons for concluding that 600 to 800 loci of the approximately 1000 loci on the X-chromosome are involved in the X-linked recessive lethal test.

  1. Autosomal recessive PGM3 mutations link glycosylation defects to atopy, immune deficiency, autoimmunity, and neurocognitive impairment

    PubMed Central

    Zhang, Yu; Yu, Xiaomin; Ichikawa, Mie; Lyons, Jonathan J.; Datta, Shrimati; Lamborn, Ian T.; Jing, Huie; Kim, Emily S.; Biancalana, Matthew; Wolfe, Lynne A.; DiMaggio, Thomas; Matthews, Helen F.; Kranick, Sarah M.; Stone, Kelly D.; Holland, Steven M.; Reich, Daniel S.; Hughes, Jason D.; Mehmet, Huseyin; McElwee, Joshua; Freeman, Alexandra F.; Freeze, Hudson H.; Su, Helen C.; Milner, Joshua D.

    2014-01-01

    Background Identifying genetic syndromes that lead to significant atopic disease can open new pathways for investigation and intervention in allergy. Objective To define a genetic syndrome of severe atopy, elevated serum IgE, immune deficiency, autoimmunity, and motor and neurocognitive impairment. Methods Eight patients from two families who had similar syndromic features were studied. Thorough clinical evaluations, including brain MRI and sensory evoked potentials, were performed. Peripheral lymphocyte flow cytometry, antibody responses, and T cell cytokine production were measured. Whole exome sequencing was performed to identify disease-causing mutations. Immunoblotting, qRT-PCR, enzymatic assays, nucleotide sugar and sugar phosphate analyses along with MALDI-TOF mass spectrometry of glycans were used to determine the molecular consequences of the mutations. Results Marked atopy and autoimmunity were associated with increased TH2 and TH17 cytokine production by CD4+ T cells. Bacterial and viral infection susceptibility were noted along with T cell lymphopenia, particularly of CD8+ T cells, and reduced memory B cells. Apparent brain hypomyelination resulted in markedly delayed evoked potentials and likely contributed to neurological abnormalities. Disease segregated with novel autosomal recessive mutations in a single gene, phosphoglucomutase 3 (PGM3). Although PGM3 protein expression was variably diminished, impaired function was demonstrated by decreased enzyme activity and reduced UDP-GlcNAc, along with decreased O- and N-linked protein glycosylation in patients’ cells. These results define a new Congenital Disorder of Glycosylation. Conclusions Autosomal recessive, hypomorphic PGM3 mutations underlie a disorder of severe atopy, immune deficiency, autoimmunity, intellectual disability and hypomyelination. PMID:24589341

  2. Prostaglandin transporter mutations cause pachydermoperiostosis with myelofibrosis.

    PubMed

    Diggle, Christine P; Parry, David A; Logan, Clare V; Laissue, Paul; Rivera, Carolina; Restrepo, Carlos Martín; Fonseca, Dora J; Morgan, Joanne E; Allanore, Yannick; Fontenay, Michaela; Wipff, Julien; Varret, Mathilde; Gibault, Laure; Dalantaeva, Nadezhda; Korbonits, Márta; Zhou, Bowen; Yuan, Gang; Harifi, Ghita; Cefle, Kivanc; Palanduz, Sukru; Akoglu, Hadim; Zwijnenburg, Petra J; Lichtenbelt, Klaske D; Aubry-Rozier, Bérengère; Superti-Furga, Andrea; Dallapiccola, Bruno; Accadia, Maria; Brancati, Francesco; Sheridan, Eamonn G; Taylor, Graham R; Carr, Ian M; Johnson, Colin A; Markham, Alexander F; Bonthron, David T

    2012-08-01

    Pachydermoperiostosis, or primary hypertrophic osteoarthropathy (PHO), is an inherited multisystem disorder, whose features closely mimic the reactive osteoarthropathy that commonly accompanies neoplastic and inflammatory pathologies. We previously described deficiency of the prostaglandin-degrading enzyme 15-hydroxyprostaglandin dehydrogenase (HPGD) as a cause of this condition, implicating elevated circulating prostaglandin E(2) (PGE(2)) as causative of PHO, and perhaps also as the principal mediator of secondary HO. However, PHO is genetically heterogeneous. Here, we use whole-exome sequencing to identify recessive mutations of the prostaglandin transporter SLCO2A1, in individuals lacking HPGD mutations. We performed exome sequencing of four probands with severe PHO, followed by conventional mutation analysis of SLCO2A1 in nine others. Biallelic SLCO2A1 mutations were identified in 12 of the 13 families. Affected individuals had elevated urinary PGE(2), but unlike HPGD-deficient patients, also excreted considerable quantities of the PGE(2) metabolite, PGE-M. Clinical differences between the two groups were also identified, notably that SLCO2A1-deficient individuals have a high frequency of severe anemia due to myelofibrosis. These findings reinforce the key role of systemic or local prostaglandin excess as the stimulus to HO. They also suggest that the induction or maintenance of hematopoietic stem cells by prostaglandin may depend upon transporter activity. PMID:22553128

  3. Proof-of-principle rapid noninvasive prenatal diagnosis of autosomal recessive founder mutations

    PubMed Central

    Zeevi, David A.; Altarescu, Gheona; Weinberg-Shukron, Ariella; Zahdeh, Fouad; Dinur, Tama; Chicco, Gaya; Herskovitz, Yair; Renbaum, Paul; Elstein, Deborah; Levy-Lahad, Ephrat; Rolfs, Arndt; Zimran, Ari

    2015-01-01

    BACKGROUND. Noninvasive prenatal testing can be used to accurately detect chromosomal aneuploidies in circulating fetal DNA; however, the necessity of parental haplotype construction is a primary drawback to noninvasive prenatal diagnosis (NIPD) of monogenic disease. Family-specific haplotype assembly is essential for accurate diagnosis of minuscule amounts of circulating cell-free fetal DNA; however, current haplotyping techniques are too time-consuming and laborious to be carried out within the limited time constraints of prenatal testing, hampering practical application of NIPD in the clinic. Here, we have addressed this pitfall and devised a universal strategy for rapid NIPD of a prevalent mutation in the Ashkenazi Jewish (AJ) population. METHODS. Pregnant AJ couples, carrying mutation(s) in GBA, which encodes acid β-glucosidase, were recruited at the SZMC Gaucher Clinic. Targeted next-generation sequencing of GBA-flanking SNPs was performed on peripheral blood samples from each couple, relevant mutation carrier family members, and unrelated individuals who are homozygotes for an AJ founder mutation. Allele-specific haplotypes were constructed based on linkage, and a consensus Gaucher disease–associated founder mutation–flanking haplotype was fine mapped. Together, these haplotypes were used for NIPD. All test results were validated by conventional prenatal or postnatal diagnostic methods. RESULTS. Ten parental alleles in eight unrelated fetuses were diagnosed successfully based on the noninvasive method developed in this study. The consensus mutation–flanking haplotype aided diagnosis for 6 of 9 founder mutation alleles. CONCLUSIONS. The founder NIPD method developed and described here is rapid, economical, and readily adaptable for prenatal testing of prevalent autosomal recessive disease-causing mutations in an assortment of worldwide populations. FUNDING. SZMC, Protalix Biotherapeutics Inc., and Centogene AG. PMID:26426075

  4. Whole exome sequencing identified novel CRB1 mutations in Chinese and Indian populations with autosomal recessive retinitis pigmentosa

    PubMed Central

    Yang, Yin; Yang, Yeming; Huang, Lulin; Zhai, Yaru; Li, Jie; Jiang, Zhilin; Gong, Bo; Fang, Hao; Kim, Ramasamy; Yang, Zhenglin; Sundaresan, Periasamy; Zhu, Xianjun; Zhou, Yu

    2016-01-01

    Retinitis pigmentosa (RP) is a leading cause of inherited blindness characterized by progressive degeneration of the retinal photoreceptor cells. This study aims to identify genetic mutations in a Chinese family RP-2236, an Indian family RP-IC-90 and 100 sporadic Indian individuals with autosomal recessive RP (arRP). Whole exome sequencing was performed on the index patients of RP-2236, RP-IC-90 and all of the 100 sporadic Indian patients. Direct Sanger sequencing was used to validate the mutations identified. Four novel mutations and one reported mutation in the crumbs homolog 1 (CRB1) gene, which has been known to cause severe retinal dystrophies, were identified. A novel homozygous splicing mutation c.2129-1G>C was found in the three patients In family RP-2236. A homozygous point mutation p.R664C was found in RP-IC-90. A novel homozygous mutation p.G1310C was identified in patient I-44, while novel compound heterozygous mutations p.N629D and p.A593T were found in patient I-7. All mutations described above were not present in the 1000 normal controls. In conclusion, we identified four novel mutations in CRB1 in a cohort of RP patients from the Chinese and Indian populations. Our data enlarges the CRB1 mutation spectrums and may provide new target loci for RP diagnose and treatment. PMID:27670293

  5. A novel frameshift mutation in KCNQ4 in a family with autosomal recessive non-syndromic hearing loss.

    PubMed

    Wasano, Koichiro; Mutai, Hideki; Obuchi, Chie; Masuda, Sawako; Matsunaga, Tatsuo

    2015-08-01

    Mutation of KCNQ4 has been reported to cause autosomal dominant non-syndromic hearing loss (DFNA2A) that usually presents as progressive hearing loss starting from mild to moderate hearing loss during childhood. Here, we identified a novel KCNQ4 mutation, c.1044_1051del8, in a family with autosomal recessive non-syndromic hearing loss. The proband was homozygous for the mutation and was born to consanguineous parents; she showed severe hearing loss that was either congenital or of early childhood onset. The proband had a sister who was heterozygous for the mutation but showed normal hearing. The mutation caused a frameshift that eliminated most of the cytoplasmic C-terminus, including the A-domain, which has an important role for protein tetramerization, and the B-segment, which is a binding site for calmodulin (CaM) that regulates channel function via Ca ions. The fact that the heterozygote had normal hearing indicates that sufficient tetramerization and CaM binding sites were present to preserve a normal phenotype even when only half the proteins contained an A-domain and B-segment. On the other hand, the severe hearing loss in the homozygote suggests that complete loss of the A-domain and B-segment in the protein caused loss of function due to the failure of tetramer formation and CaM binding. This family suggests that some KCNQ4 mutations can cause autosomal recessive hearing loss with more severe phenotype in addition to autosomal dominant hearing loss with milder phenotype. This genotype-phenotype correlation is analogous to that in KCNQ1 which causes autosomal dominant hereditary long QT syndrome 1 with milder phenotype and the autosomal recessive Jervell and Lange-Nielsen syndrome 1 with more severe phenotype due to deletion of the cytoplasmic C-terminus of the potassium channel.

  6. Whole exome resequencing reveals recessive mutations in TRAP1 in individuals with CAKUT and VACTERL association

    PubMed Central

    Saisawat, Pawaree; Kohl, Stefan; Hilger, Alina C.; Hwang, Daw-Yang; Gee, Heon Yung; Dworschak, Gabriel C.; Tasic, Velibor; Pennimpede, Tracie; Natarajan, Sivakumar; Sperry, Ethan; Matassa, Danilo S.; Stajić, Nataša; Bogdanovic, Radovan; de Blaauw, Ivo; Marcelis, Carlo L.M.; Wijers, Charlotte H.W.; Bartels, Enrika; Schmiedeke, Eberhard; Schmidt, Dominik; Mäzheuser, Stefanie; Grasshoff-Derr, Sabine; Holland-Cunz, Stefan; Ludwig, Michael; Nöhen, Markus M.; Draaken, Markus; Brosens, Erwin; Heij, Hugo; Tibboel, Dick; Herrmann, Bernhard G.; Solomon, Benjamin D.; de Klein, Annelies; van Rooij, Iris A.L.M.; Esposito, Franca; Reutter, Heiko M.; Hildebrandt, Friedhelm

    2014-01-01

    Congenital abnormalities of the kidney and urinary tract (CAKUT) account for approximately half of children with chronic kidney disease and they are the most frequent cause of end-stage renal disease in children in the US. However, its genetic etiology remains mostly elusive. VACTERL association is a rare disorder that involves congenital abnormalities in multiple organs including the kidney and urinary tract in up to 60% of the cases. By homozygosity mapping and whole exome resequencing combined with high-throughput mutation analysis by array-based multiplex PCR and next-generation sequencing, we identified recessive mutations in the gene TNF receptor-associated protein 1 (TRAP1) in two families with isolated CAKUT and three families with VACTERL association. TRAP1 is a heat shock protein 90-related mitochondrial chaperone possibly involved in antiapoptotic and endoplasmic reticulum-stress signaling. Trap1 is expressed in renal epithelia of developing mouse kidney E13.5 and in the kidney of adult rats, most prominently in proximal tubules and in thick medullary ascending limbs of Henle’s loop. Thus, we identified mutations in TRAP1 as highly likely causing CAKUT or CAKUT in VACTERL association. PMID:24152966

  7. Novel AE1 mutations in recessive distal renal tubular acidosis. Loss-of-function is rescued by glycophorin A.

    PubMed

    Tanphaichitr, V S; Sumboonnanonda, A; Ideguchi, H; Shayakul, C; Brugnara, C; Takao, M; Veerakul, G; Alper, S L

    1998-12-15

    The AE1 gene encodes band 3 Cl-/HCO3- exchangers that are expressed both in the erythrocyte and in the acid-secreting, type A intercalated cells of the kidney. Kidney AE1 contributes to urinary acidification by providing the major exit route for HCO3- across the basolateral membrane. Several AE1 mutations cosegregate with dominantly transmitted nonsyndromic renal tubular acidosis (dRTA). However, the modest degree of in vitro hypofunction exhibited by these dRTA-associated mutations fails to explain the disease phenotype in light of the normal urinary acidification associated with the complete loss-of-function exhibited by AE1 mutations linked to dominant spherocytosis. We report here novel AE1 mutations linked to a recessive syndrome of dRTA and hemolytic anemia in which red cell anion transport is normal. Both affected individuals were triply homozygous for two benign mutations M31T and K56E and for the loss-of-function mutation, G701D. AE1 G701D loss-of-function was accompanied by impaired trafficking to the Xenopus oocyte surface. Coexpression with AE1 G701D of the erythroid AE1 chaperonin, glycophorin A, rescued both AE1-mediated Cl- transport and AE1 surface expression in oocytes. The genetic and functional data both suggest that the homozygous AE1 G701D mutation causes recessively transmitted dRTA in this kindred with apparently normal erythroid anion transport. PMID:9854053

  8. Autosomal Recessive Primary Microcephaly (MCPH): clinical manifestations, genetic heterogeneity and mutation continuum.

    PubMed

    Mahmood, Saqib; Ahmad, Wasim; Hassan, Muhammad J

    2011-01-01

    Autosomal Recessive Primary Microcephaly (MCPH) is a rare disorder of neurogenic mitosis characterized by reduced head circumference at birth with variable degree of mental retardation. In MCPH patients, brain size reduced to almost one-third of its original volume due to reduced number of generated cerebral cortical neurons during embryonic neurogensis. So far, seven genetic loci (MCPH1-7) for this condition have been mapped with seven corresponding genes (MCPH1, WDR62, CDK5RAP2, CEP152, ASPM, CENPJ, and STIL) identified from different world populations. Contribution of ASPM and WDR62 gene mutations in MCPH World wide is more than 50%. By and large, primary microcephaly patients are phenotypically indistinguishable, however, recent studies in patients with mutations in MCPH1, WDR62 and ASPM genes showed a broader clinical and/or cellular phenotype. It has been proposed that mutations in MCPH genes can cause the disease phenotype by disturbing: 1) orientation of mitotic spindles, 2) chromosome condensation mechanism during embryonic neurogenesis, 3) DNA damage-response signaling, 4) transcriptional regulations and microtubule dynamics, 5) certain unknown centrosomal mechanisms that control the number of neurons generated by neural precursor cells. Recent discoveries of mammalian models for MCPH have open up horizons for researchers to add more knowledge regarding the etiology and pathophysiology of MCPH. High incidence of MCPH in Pakistani population reflects the most probable involvement of consanguinity. Genetic counseling and clinical management through carrier detection/prenatal diagnosis in MCPH families can help reducing the incidence of this autosomal recessive disorder. PMID:21668957

  9. Recessive mutations in SPTBN2 implicate β-III spectrin in both cognitive and motor development.

    PubMed

    Lise, Stefano; Clarkson, Yvonne; Perkins, Emma; Kwasniewska, Alexandra; Sadighi Akha, Elham; Schnekenberg, Ricardo Parolin; Suminaite, Daumante; Hope, Jilly; Baker, Ian; Gregory, Lorna; Green, Angie; Allan, Chris; Lamble, Sarah; Jayawant, Sandeep; Quaghebeur, Gerardine; Cader, M Zameel; Hughes, Sarah; Armstrong, Richard J E; Kanapin, Alexander; Rimmer, Andrew; Lunter, Gerton; Mathieson, Iain; Cazier, Jean-Baptiste; Buck, David; Taylor, Jenny C; Bentley, David; McVean, Gilean; Donnelly, Peter; Knight, Samantha J L; Jackson, Mandy; Ragoussis, Jiannis; Németh, Andrea H

    2012-01-01

    β-III spectrin is present in the brain and is known to be important in the function of the cerebellum. Heterozygous mutations in SPTBN2, the gene encoding β-III spectrin, cause Spinocerebellar Ataxia Type 5 (SCA5), an adult-onset, slowly progressive, autosomal-dominant pure cerebellar ataxia. SCA5 is sometimes known as "Lincoln ataxia," because the largest known family is descended from relatives of the United States President Abraham Lincoln. Using targeted capture and next-generation sequencing, we identified a homozygous stop codon in SPTBN2 in a consanguineous family in which childhood developmental ataxia co-segregates with cognitive impairment. The cognitive impairment could result from mutations in a second gene, but further analysis using whole-genome sequencing combined with SNP array analysis did not reveal any evidence of other mutations. We also examined a mouse knockout of β-III spectrin in which ataxia and progressive degeneration of cerebellar Purkinje cells has been previously reported and found morphological abnormalities in neurons from prefrontal cortex and deficits in object recognition tasks, consistent with the human cognitive phenotype. These data provide the first evidence that β-III spectrin plays an important role in cortical brain development and cognition, in addition to its function in the cerebellum; and we conclude that cognitive impairment is an integral part of this novel recessive ataxic syndrome, Spectrin-associated Autosomal Recessive Cerebellar Ataxia type 1 (SPARCA1). In addition, the identification of SPARCA1 and normal heterozygous carriers of the stop codon in SPTBN2 provides insights into the mechanism of molecular dominance in SCA5 and demonstrates that the cell-specific repertoire of spectrin subunits underlies a novel group of disorders, the neuronal spectrinopathies, which includes SCA5, SPARCA1, and a form of West syndrome.

  10. Mutations in the PLEKHG5 gene is relevant with autosomal recessive intermediate Charcot-Marie-Tooth disease

    PubMed Central

    2013-01-01

    Background Mutations in the Pleckstrin homology domain-containing, family G member 5 (PLEKHG5) gene has been reported in a family harboring an autosomal recessive lower motor neuron disease (LMND). However, the PLEKHG5 mutation has not been described to cause Charcot-Marie-Tooth disease (CMT). Methods To identify the causative mutation in an autosomal recessive intermediate CMT (RI-CMT) family with childhood onset, whole exome sequencing (WES), histopathology, and lower leg MRIs were performed. Expression and activity of each mutant protein were analyzed. Results We identified novel compound heterozygous (p.Thr663Met and p.Gly820Arg) mutations in the PLEKHG5 gene in the present family. The patient revealed clinical manifestations of sensory neuropathy. Fatty replacements in the distal lower leg muscles were more severe than in the thigh muscles. Although the symptoms and signs of this patient harboring slow nerve conduction velocities suggested the possibility of demyelinating neuropathy, a distal sural nerve biopsy was compatible with axonal neuropathy. Immunohistochemical analysis revealed that the patient has a low level of PLEKHG5 in the distal sural nerve and an in vitro assay suggested that the mutant proteins have a defect in activating the NF-κB signaling pathway. Conclusions This study identifies compound heterozygous PLEKHG5 mutations as the cause of RI-CMT. We suggest that PLEKHG5 might play a role in the peripheral motor and sensory nervous system. This study expands the phenotypic spectrum of PLEKHG5 mutations. PMID:23844677

  11. Novel mutations in the genes TGM1 and ALOXE3 underlying autosomal recessive congenital ichthyosis

    PubMed Central

    Ullah, Rahim; Ansar, Muhammad; Durrani, Zaka Ullah; Lee, Kwanghyuk; Santos-Cortez, Regie Lyn P.; Muhammad, Dost; Ali, Mahboob; Zia, Muhammad; Ayub, Muhammad; Khan, Suliman; Smith, Josh D.; Nickerson, Deborah A.; Shendure, Jay; Bamshad, Michael; Leal, Suzanne M.; Ahmad, Wasim

    2016-01-01

    Background Ichthyoses are clinically characterized by scaling or hyperkeratosis of the skin or both. It can be an isolated condition limited to the skin or appear secondarily with involvement of other cutaneous or systemic abnormalities. Methods The present study investigated clinical and molecular characterization of three consanguineous families (A, B, C) segregating two different forms of autosomal recessive congenital ichthyosis (ARCI). Linkage in three consanguineous families (A, B, C) segregating two different forms of ARCI was searched by typing microsatellite and single nucleotide polymorphism marker analysis. Sequencing of the two genes TGM1 and ALOXE3 was performed by the dideoxy chain termination method. Results Genome-wide linkage analysis established linkage in family A to TGM1 gene on chromosome 14q11 and in families B and C to ALOXE3 gene on chromosome 17p13. Subsequently, sequencing of these genes using samples from affected family members led to the identification of three novel mutations: a missense variant p.Trp455Arg in TGM1 (family A); a nonsense variant p.Arg140* in ALOXE3 (family B); and a complex rearrangement in ALOXE3 (family C). Conclusion The present study further extends the spectrum of mutations in the two genes involved in causing ARCI. Characterizing the clinical spectrum resulting from mutations in the TGM1 and ALOXE3 genes will improve diagnosis and may direct clinical care of the family members. PMID:26578203

  12. Spinocerebellar ataxia with axonal neuropathy: consequence of a Tdp1 recessive neomorphic mutation?

    PubMed Central

    Hirano, Ryuki; Interthal, Heidrun; Huang, Cheng; Nakamura, Tomonori; Deguchi, Kimiko; Choi, Kunho; Bhattacharjee, Meenakshi B; Arimura, Kimiyoshi; Umehara, Fujio; Izumo, Shuji; Northrop, Jennifer L; Salih, Mustafa A M; Inoue, Ken; Armstrong, Dawna L; Champoux, James J; Takashima, Hiroshi; Boerkoel, Cornelius F

    2007-01-01

    Tyrosyl-DNA phosphodiesterase 1 (Tdp1) cleaves the phosphodiester bond between a covalently stalled topoisomerase I (Topo I) and the 3′ end of DNA. Stalling of Topo I at DNA strand breaks is induced by endogenous DNA damage and the Topo I-specific anticancer drug camptothecin (CPT). The H493R mutation of Tdp1 causes the neurodegenerative disorder spinocerebellar ataxia with axonal neuropathy (SCAN1). Contrary to the hypothesis that SCAN1 arises from catalytically inactive Tdp1, Tdp1−/− mice are indistinguishable from wild-type mice, physically, histologically, behaviorally, and electrophysiologically. However, compared to wild-type mice, Tdp1−/− mice are hypersensitive to CPT and bleomycin but not to etoposide. Consistent with earlier in vitro studies, we show that the H493R Tdp1 mutant protein retains residual activity and becomes covalently trapped on the DNA after CPT treatment of SCAN1 cells. This result provides a direct demonstration that Tdp1 repairs Topo I covalent lesions in vivo and suggests that SCAN1 arises from the recessive neomorphic mutation H493R. This is a novel mechanism for disease since neomorphic mutations are generally dominant. PMID:17948061

  13. The mouse rumpshaker mutation of the proteolipid protein in human X-linked recessive spastic paraplegia

    SciTech Connect

    Kobayashi, H.; Hoffman, E.P.; Matise, T.C.

    1994-09-01

    X-linked recessive spastic paraplegia is a rare neurodegenerative disorder characterized by slowly progressive weakness and spasticity of the lower extremities. We have recently genetically analyzed the original X-linked recessive spastic paraplegia family reported by Johnston and McKusick in 1962. We employed a fluorescent multiplex CA repeat strategy using a 22 locus, 10 cM framework map of the human X chromosome and localized the gene within a 36 cM region of Xq2l.3-q24 which includes the PLP locus. Saugier-Veber et al. recently reported a point mutation (His139Tyr) in exon 3B of the PLP gene in an X-linked recessive spastic paraplegia family (SPG2). This family shows no optic atrophy, in contrast to the family we have studied. This data showed that SPG2 and Pelizaeus-Merzbacher disease were allelic disorders. We investigated the PLP gene as a candidate gene for the original X-linked recessive spastic paraplegia family using SSCP and direct sequencing methods. We found a point mutation (T to C) in exon 4 of affected males which alters the amino-acid (Ile to Thr) at residue 186. This change was absent in the unaffected males of the family and in 40 unrelated control females (80 X chromosomes). Surprisingly, this mutation is identical to the mutation previously identified in the rumpshaker mouse model. The complete homology between both the mouse and human PLP sequence, and the mouse rumpshaker mutation and human spastic paraplegia mutation in our family, permit direct parallels to be drawn with regards to pathophysiology. Our data indicates that the well-documented and striking clinical differences between Pelizaeus-Merzbacher disease and X-linked recessive spastic paraplegia is due to the specific effect of different mutations of the human PLP gene on oligodendrocyte differentiation and development and on later myelin production and maintenance.

  14. An Estimate of the Average Number of Recessive Lethal Mutations Carried by Humans

    PubMed Central

    Gao, Ziyue; Waggoner, Darrel; Stephens, Matthew; Ober, Carole; Przeworski, Molly

    2015-01-01

    The effects of inbreeding on human health depend critically on the number and severity of recessive, deleterious mutations carried by individuals. In humans, existing estimates of these quantities are based on comparisons between consanguineous and nonconsanguineous couples, an approach that confounds socioeconomic and genetic effects of inbreeding. To overcome this limitation, we focused on a founder population that practices a communal lifestyle, for which there is almost complete Mendelian disease ascertainment and a known pedigree. Focusing on recessive lethal diseases and simulating allele transmissions, we estimated that each haploid set of human autosomes carries on average 0.29 (95% credible interval [0.10, 0.84]) recessive alleles that lead to complete sterility or death by reproductive age when homozygous. Comparison to existing estimates in humans suggests that a substantial fraction of the total burden imposed by recessive deleterious variants is due to single mutations that lead to sterility or death between birth and reproductive age. In turn, comparison to estimates from other eukaryotes points to a surprising constancy of the average number of recessive lethal mutations across organisms with markedly different genome sizes. PMID:25697177

  15. COL11A2 mutation associated with autosomal recessive Weissenbacher-Zweymuller syndrome: molecular and clinical overlap with otospondylomegaepiphyseal dysplasia (OSMED).

    PubMed

    Harel, Tamar; Rabinowitz, Ronen; Hendler, Netta; Galil, Aharon; Flusser, Hagit; Chemke, Juan; Gradstein, Libe; Lifshitz, Tova; Ofir, Rivka; Elbedour, Khalil; Birk, Ohad S

    2005-01-01

    Autosomal recessive Weissenbacher-Zweymuller syndrome (WZS) is a skeletal dysplasia characterized by rhizomelic dwarfism and severe hearing loss. Mutations in the COL11A2 gene have been implicated in causing the autosomal dominant form of this syndrome as well as non-ocular Stickler syndrome and the autosomal recessive syndrome otospondylomegaepiphyseal dysplasia (OSMED). In a consanguineous Bedouin tribe living in Southern Israel, five individuals affected by autosomal recessive WZS were available for genetic analysis. Homozygosity of a mutation in the COL11A2 gene was found in all affected individuals. This finding lends molecular support to the clinical notion that autosomal recessive WZS and OSMED are a single entity. PMID:15558753

  16. Novel mutations confirm that COL11A2 is responsible for autosomal recessive non-syndromic hearing loss DFNB53.

    PubMed

    Chakchouk, Imen; Grati, M'hamed; Bademci, Guney; Bensaid, Mariem; Ma, Qi; Chakroun, Amine; Foster, Joseph; Yan, Denise; Duman, Duygu; Diaz-Horta, Oscar; Ghorbel, Abdelmonem; Mittal, Rahul; Farooq, Amjad; Tekin, Mustafa; Masmoudi, Saber; Liu, Xue Zhong

    2015-08-01

    Hearing loss (HL) is a major public health issue. It is clinically and genetically heterogeneous.The identification of the causal mutation is important for early diagnosis, clinical follow-up, and genetic counseling. HL due to mutations in COL11A2, encoding collagen type XI alpha-2, can be non-syndromic autosomal-dominant or autosomal-recessive, and also syndromic as in Otospondylomegaepiphyseal Dysplasia, Stickler syndrome type III, and Weissenbacher-Zweymuller syndrome. However, thus far only one mutation co-segregating with autosomal recessive non-syndromic hearing loss (ARNSHL) in a single family has been reported. In this study, whole exome sequencing of two consanguineous families with ARNSHL from Tunisia and Turkey revealed two novel causative COL11A2 mutations, c.109G > T (p.Ala37Ser) and c.2662C > A (p.Pro888Thr). The variants identified co-segregated with deafness in both families. All homozygous individuals in those families had early onset profound hearing loss across all frequencies without syndromic findings. The variants are predicted to be damaging the protein function. The p.Pro888Thr mutation affects a -Gly-X-Y- triplet repeat motif. The novel p.Ala37Ser is the first missense mutation located in the NC4 domain of the COL11A2 protein. Structural model suggests that this mutation will likely obliterate, or at least partially compromise, the ability of NC4 domain to interact with its cognate ligands. In conclusion, we confirm that COL11A2 mutations cause ARNSHL and broaden the mutation spectrum that may shed new light on genotype-phenotype correlation for the associated phenotypes and clinical follow-up. PMID:25633957

  17. Novel mutations confirm that COL11A2 is responsible for autosomal recessive non-syndromic hearing loss DFNB53

    PubMed Central

    Chakchouk, Imen; Grati, M’hamed; Bademci, Guney; Bensaid, Mariem; Ma, Qi; Chakroun, Amine; Foster, Joseph; Yan, Denise; Duman, Duygu; Diaz-Horta, Oscar; Ghorbel, Abdelmonem; Mittal, Rahul; Farooq, Amjad; Tekin, Mustafa

    2015-01-01

    Hearing loss (HL) is a major public health issue. It is clinically and genetically heterogeneous. The identification of the causal mutation is important for early diagnosis, clinical follow-up, and genetic counseling. HL due to mutations in COL11A2, encoding collagen type XI alpha-2, can be non-syndromic autosomal-dominant or autosomal-recessive, and also syndromic as in Otospondylomegaepiphyseal Dysplasia, Stickler syndrome type III, and Weissenbacher–Zweymuller syndrome. However, thus far only one mutation co-segregating with autosomal recessive non-syndromic hearing loss (ARNSHL) in a single family has been reported. In this study, whole exome sequencing of two consanguineous families with ARNSHL from Tunisia and Turkey revealed two novel causative COL11A2 mutations, c.109G > T (p.Ala37Ser) and c.2662C > A (p.Pro888Thr). The variants identified co-segregated with deafness in both families. All homozygous individuals in those families had early onset profound hearing loss across all frequencies without syndromic findings. The variants are predicted to be damaging the protein function. The p.Pro888Thr mutation affects a -Gly-X–Y- triplet repeat motif. The novel p.Ala37Ser is the first missense mutation located in the NC4 domain of the COL11A2 protein. Structural model suggests that this mutation will likely obliterate, or at least partially compromise, the ability of NC4 domain to interact with its cognate ligands. In conclusion, we confirm that COL11A2 mutations cause ARNSHL and broaden the mutation spectrum that may shed new light on genotype–phenotype correlation for the associated phenotypes and clinical follow-up. PMID:25633957

  18. Recessive optic atrophy, sensorimotor neuropathy and cataract associated with novel compound heterozygous mutations in OPA1

    PubMed Central

    LEE, JINHO; JUNG, SUNG-CHUL; HONG, YOUNG BIN; YOO, JEONG HYUN; KOO, HEASOO; LEE, JA HYUN; HONG, HYUN DAE; KIM, SANG-BEOM; CHUNG, KI WHA; CHOI, BYUNG-OK

    2016-01-01

    Mutations in the optic atrophy 1 gene (OPA1) are associated with autosomal dominant optic atrophy and 20% of patients demonstrate extra-ocular manifestations. In addition to these autosomal dominant cases, only a few syndromic cases have been reported thus far with compound heterozygous OPA1 mutations, suggestive of either recessive or semi-dominant patterns of inheritance. The majority of these patients were diagnosed with Behr syndrome, characterized by optic atrophy, ataxia and peripheral neuropathy. The present study describes a 10-year-old boy with Behr syndrome presenting with early-onset severe optic atrophy, sensorimotor neuropathy, ataxia and congenital cataracts. He had optic atrophy and was declared legally blind at six years old. Electrophysiological, radiological, and histopathological findings were compatible with axonal sensorimotor polyneuropathy. At birth, he presented with a congenital cataract, which has not been previously described in patients with OPA1 mutations. Whole exome sequencing indicated a pair of novel compound heterozygous mutations: p.L620fs*13 (c.1857–1858delinsT) and p.R905Q (c.G2714A). Neither mutation was observed in controls (n=300), and thus, they were predicted to be pathogenic by multiple in silico analyses. The mutation sites were highly conserved throughout different vertebrate species. The patients parents did not have any ophthalmic or neurologic symptoms and the results of electrophysiological studies were normal, suggestive of an autosomal recessive pattern of inheritance. The present study identified novel compound heterozygous OPA1 mutations in a patient with recessive optic atrophy, sensorimotor neuropathy and congenital cataracts, indicating an expansion of the clinical spectrum of pathologies associated with OPA1 mutations. Thus, OPA1 gene screening is advisable in the workup of patients with recessive optic atrophy, particularly with Behr syndrome and cataracts. PMID:27150940

  19. FAT1 mutations cause a glomerulotubular nephropathy.

    PubMed

    Gee, Heon Yung; Sadowski, Carolin E; Aggarwal, Pardeep K; Porath, Jonathan D; Yakulov, Toma A; Schueler, Markus; Lovric, Svjetlana; Ashraf, Shazia; Braun, Daniela A; Halbritter, Jan; Fang, Humphrey; Airik, Rannar; Vega-Warner, Virginia; Cho, Kyeong Jee; Chan, Timothy A; Morris, Luc G T; ffrench-Constant, Charles; Allen, Nicholas; McNeill, Helen; Büscher, Rainer; Kyrieleis, Henriette; Wallot, Michael; Gaspert, Ariana; Kistler, Thomas; Milford, David V; Saleem, Moin A; Keng, Wee Teik; Alexander, Stephen I; Valentini, Rudolph P; Licht, Christoph; Teh, Jun C; Bogdanovic, Radovan; Koziell, Ania; Bierzynska, Agnieszka; Soliman, Neveen A; Otto, Edgar A; Lifton, Richard P; Holzman, Lawrence B; Sibinga, Nicholas E S; Walz, Gerd; Tufro, Alda; Hildebrandt, Friedhelm

    2016-01-01

    Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease (CKD). Here we show that recessive mutations in FAT1 cause a distinct renal disease entity in four families with a combination of SRNS, tubular ectasia, haematuria and facultative neurological involvement. Loss of FAT1 results in decreased cell adhesion and migration in fibroblasts and podocytes and the decreased migration is partially reversed by a RAC1/CDC42 activator. Podocyte-specific deletion of Fat1 in mice induces abnormal glomerular filtration barrier development, leading to podocyte foot process effacement. Knockdown of Fat1 in renal tubular cells reduces migration, decreases active RAC1 and CDC42, and induces defects in lumen formation. Knockdown of fat1 in zebrafish causes pronephric cysts, which is partially rescued by RAC1/CDC42 activators, confirming a role of the two small GTPases in the pathogenesis. These findings provide new insights into the pathogenesis of SRNS and tubulopathy, linking FAT1 and RAC1/CDC42 to podocyte and tubular cell function. PMID:26905694

  20. FAT1 mutations cause a glomerulotubular nephropathy

    PubMed Central

    Gee, Heon Yung; Sadowski, Carolin E.; Aggarwal, Pardeep K.; Porath, Jonathan D.; Yakulov, Toma A.; Schueler, Markus; Lovric, Svjetlana; Ashraf, Shazia; Braun, Daniela A.; Halbritter, Jan; Fang, Humphrey; Airik, Rannar; Vega-Warner, Virginia; Cho, Kyeong Jee; Chan, Timothy A.; Morris, Luc G. T.; ffrench-Constant, Charles; Allen, Nicholas; McNeill, Helen; Büscher, Rainer; Kyrieleis, Henriette; Wallot, Michael; Gaspert, Ariana; Kistler, Thomas; Milford, David V.; Saleem, Moin A.; Keng, Wee Teik; Alexander, Stephen I.; Valentini, Rudolph P.; Licht, Christoph; Teh, Jun C.; Bogdanovic, Radovan; Koziell, Ania; Bierzynska, Agnieszka; Soliman, Neveen A.; Otto, Edgar A.; Lifton, Richard P.; Holzman, Lawrence B.; Sibinga, Nicholas E. S.; Walz, Gerd; Tufro, Alda; Hildebrandt, Friedhelm

    2016-01-01

    Steroid-resistant nephrotic syndrome (SRNS) causes 15% of chronic kidney disease (CKD). Here we show that recessive mutations in FAT1 cause a distinct renal disease entity in four families with a combination of SRNS, tubular ectasia, haematuria and facultative neurological involvement. Loss of FAT1 results in decreased cell adhesion and migration in fibroblasts and podocytes and the decreased migration is partially reversed by a RAC1/CDC42 activator. Podocyte-specific deletion of Fat1 in mice induces abnormal glomerular filtration barrier development, leading to podocyte foot process effacement. Knockdown of Fat1 in renal tubular cells reduces migration, decreases active RAC1 and CDC42, and induces defects in lumen formation. Knockdown of fat1 in zebrafish causes pronephric cysts, which is partially rescued by RAC1/CDC42 activators, confirming a role of the two small GTPases in the pathogenesis. These findings provide new insights into the pathogenesis of SRNS and tubulopathy, linking FAT1 and RAC1/CDC42 to podocyte and tubular cell function. PMID:26905694

  1. Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction.

    PubMed Central

    Boerjan, W; Cervera, M T; Delarue, M; Beeckman, T; Dewitte, W; Bellini, C; Caboche, M; Van Onckelen, H; Van Montagu, M; Inzé, D

    1995-01-01

    We have isolated seven allelic recessive Arabidopsis mutants, designated superroot (sur1-1 to sur1-7), displaying several abnormalities reminiscent of auxin effects. These characteristics include small and epinastic cotyledons, an elongated hypocotyl in which the connection between the stele and cortical and epidermal cells disintegrates, the development of excess adventitious and lateral roots, a reduced number of leaves, and the absence of an inflorescence. When germinated in the dark, sur1 mutants did not develop the apical hook characteristic of etiolated seedlings. We were able to phenocopy the Sur1- phenotype by supplying auxin to wild-type seedlings, to propagate sur1 explants on phytohormone-deficient medium, and to regenerate shoots from these explants by the addition of cytokinins alone to the culture medium. Analysis by gas chromatography coupled to mass spectrometry indicated increased levels of both free and conjugated indole-3-acetic acid. sur1 was crossed to the mutant axr2 and the altered-auxin response mutant ctr1. The phenotype of both double mutants was additive. The sur1 gene was mapped on chromosome 2 at 0.5 centimorgans from the gene encoding phytochrome B. PMID:8589625

  2. Gingival recession: its causes and types, and the importance of orthodontic treatment

    PubMed Central

    Jati, Ana Suzy; Furquim, Laurindo Zanco; Consolaro, Alberto

    2016-01-01

    abstract Gingival recession has direct causes and predisposing factors. Orthodontic treatment is able to prevent recession and even contribute to its treatment, with or without periodontal approach, depending on the type and severity of gingival tissue damage. There is no evidence on the fact that orthodontic treatment alone might induce gingival recession, although it might lead the affected teeth (usually mandibular incisors or maxillary canines) to be involved in situations that act as predisposing factors, allowing direct causes to act and, therefore, trigger recession, especially when the buccal bone plate is very thin or presents with dehiscence. Several aspects regarding the relationship between orthodontic treatment and gingival recession have been addressed, and so has the importance of the periosteum to the mechanism of gingival recession formation. Clinical as well as experimental trials on the subject would help to clarify this matter, of which understanding is not very deep in the related literature. PMID:27409650

  3. Gingival recession: its causes and types, and the importance of orthodontic treatment.

    PubMed

    Jati, Ana Suzy; Furquim, Laurindo Zanco; Consolaro, Alberto

    2016-06-01

    Gingival recession has direct causes and predisposing factors. Orthodontic treatment is able to prevent recession and even contribute to its treatment, with or without periodontal approach, depending on the type and severity of gingival tissue damage. There is no evidence on the fact that orthodontic treatment alone might induce gingival recession, although it might lead the affected teeth (usually mandibular incisors or maxillary canines) to be involved in situations that act as predisposing factors, allowing direct causes to act and, therefore, trigger recession, especially when the buccal bone plate is very thin or presents with dehiscence. Several aspects regarding the relationship between orthodontic treatment and gingival recession have been addressed, and so has the importance of the periosteum to the mechanism of gingival recession formation. Clinical as well as experimental trials on the subject would help to clarify this matter, of which understanding is not very deep in the related literature. PMID:27409650

  4. Autosomal Recessive Retinitis Pigmentosa with Early Macular Affectation Caused by Premature Truncation in PROM1

    PubMed Central

    Permanyer, Jon; Navarro, Rafael; Friedman, James; Pomares, Esther; Castro-Navarro, Joaquín; Marfany, Gemma; Swaroop, Anand

    2010-01-01

    Purpose. To identify the genetic basis of a large consanguineous Spanish pedigree affected with autosomal recessive retinitis pigmentosa (arRP) with premature macular atrophy and myopia. Methods. After a high-throughput cosegregation gene chip was used to exclude all known RP and Leber congenital amaurosis (LCA) candidates, genome-wide screening and linkage analysis were performed. Direct mutational screening identified the pathogenic mutation, and primers were designed to obtain the RT-PCR products for isoform characterization. Results. Mutational analysis detected a novel homozygous PROM1 mutation, c.869delG in exon 8 cosegregating with the disease. This variant causes a frameshift that introduces a premature stop codon, producing truncation of approximately two-thirds of the protein. Analysis of PROM1 expression in the lymphocytes of patients, carriers, and control subjects revealed an aberrant transcript that is degraded by the nonsense-mediated decay pathway, suggesting that the disease is caused by the absence of the PROM1 protein. Three (s2, s11 and s12) of the seven alternatively spliced isoforms reported in humans, accounted for 98% of the transcripts in the retina. Given that these three contained exon 8, no PROM1 isoform is expected in the affected retinas. Conclusions. A remarkable clinical finding in the affected family is early macular atrophy with concentric spared areas. The authors propose that the hallmark of PROM1 truncating mutations is early and severe progressive degeneration of both rods and cones and highlight this gene as a candidate of choice to prioritize in the molecular genetic study of patients with noncanonical clinical peripheral and macular affectation. PMID:20042663

  5. Functional Recovery of AQP2 Recessive Mutations Through Hetero-Oligomerization with Wild-Type Counterpart.

    PubMed

    El Tarazi, Abdulah; Lussier, Yoann; Da Cal, Sandra; Bissonnette, Pierre; Bichet, Daniel G

    2016-01-01

    Aquaporin-2 (AQP2) is a homotetrameric water channel responsible for the final water reuptake in the kidney. Mutations in the protein induce nephrogenic diabetes insipidus (NDI), which challenges the water balance by producing large urinary volumes. Although recessive AQP2 mutations are believed to generate non-functional and monomeric proteins, the literature identifies several mild mutations which suggest the existence of mixed wt/mut tetramers likely to carry function in heterozygotes. Using Xenopus oocytes, we tested this hypothesis and found that mild mutants (V24A, D150E) can associate with wt-AQP2 in mixed heteromers, providing clear functional gain in the process (62 ± 17% and 63 ± 17% increases, respectively), conversely to the strong monomeric R187C mutant which fails to associate with wt-AQP2. In kidney cells, both V24A and D150E display restored targeting while R187C remains in intracellular stores. Using a collection of mutations to expand recovery analyses, we demonstrate that inter-unit contacts are central to this recovery process. These results not only present the ground data for the functional recovery of recessive AQP2 mutants through heteromerization, which prompt to revisit the accepted NDI model, but more importantly describe a general recovery process that could impact on all multimeric systems where recessive mutations are found. PMID:27641679

  6. Functional Recovery of AQP2 Recessive Mutations Through Hetero-Oligomerization with Wild-Type Counterpart

    PubMed Central

    El Tarazi, Abdulah; Lussier, Yoann; Da Cal, Sandra; Bissonnette, Pierre; Bichet, Daniel G.

    2016-01-01

    Aquaporin-2 (AQP2) is a homotetrameric water channel responsible for the final water reuptake in the kidney. Mutations in the protein induce nephrogenic diabetes insipidus (NDI), which challenges the water balance by producing large urinary volumes. Although recessive AQP2 mutations are believed to generate non-functional and monomeric proteins, the literature identifies several mild mutations which suggest the existence of mixed wt/mut tetramers likely to carry function in heterozygotes. Using Xenopus oocytes, we tested this hypothesis and found that mild mutants (V24A, D150E) can associate with wt-AQP2 in mixed heteromers, providing clear functional gain in the process (62 ± 17% and 63 ± 17% increases, respectively), conversely to the strong monomeric R187C mutant which fails to associate with wt-AQP2. In kidney cells, both V24A and D150E display restored targeting while R187C remains in intracellular stores. Using a collection of mutations to expand recovery analyses, we demonstrate that inter-unit contacts are central to this recovery process. These results not only present the ground data for the functional recovery of recessive AQP2 mutants through heteromerization, which prompt to revisit the accepted NDI model, but more importantly describe a general recovery process that could impact on all multimeric systems where recessive mutations are found. PMID:27641679

  7. Cartilage matrix deficiency (cmd): a new autosomal recessive lethal mutation in the mouse.

    PubMed

    Rittenhouse, E; Dunn, L C; Cookingham, J; Calo, C; Spiegelman, M; Dooher, G B; Bennett, D

    1978-02-01

    A new autosomal recessive lethal mutation in the mouse designated cartilage matrix deficiency (cmd) is described. Homozygotes are dwarfed, and have abnormally short trunk, limbs, tail and snout, as well as a protruding tongue and cleft palate. The abdomen is distended because the foreshortened rib cage and spinal column forces the liver ventrad from its normal location. Histological and electron microscopic study reveals a deficiency of cartilage matrix in tracheal cartilage and in all cartilagenous bones examined. The syndrome closely resembles the rare lethal condition achondrogenesis, found in human infants, which is also believed to be due to an autosomal recessive gene. PMID:632744

  8. Mutation Screening of Multiple Genes in Spanish Patients with Autosomal Recessive Retinitis Pigmentosa by Targeted Resequencing

    PubMed Central

    González-del Pozo, María; Borrego, Salud; Barragán, Isabel; Pieras, Juan I.; Santoyo, Javier; Matamala, Nerea; Naranjo, Belén; Dopazo, Joaquín; Antiñolo, Guillermo

    2011-01-01

    Retinitis Pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterised ultimately by the loss of photoreceptor cells. RP is the leading cause of visual loss in individuals younger than 60 years, with a prevalence of about 1 in 4000. The molecular genetic diagnosis of autosomal recessive RP (arRP) is challenging due to the large genetic and clinical heterogeneity. Traditional methods for sequencing arRP genes are often laborious and not easily available and a screening technique that enables the rapid detection of the genetic cause would be very helpful in the clinical practice. The goal of this study was to develop and apply microarray-based resequencing technology capable of detecting both known and novel mutations on a single high-throughput platform. Hence, the coding regions and exon/intron boundaries of 16 arRP genes were resequenced using microarrays in 102 Spanish patients with clinical diagnosis of arRP. All the detected variations were confirmed by direct sequencing and potential pathogenicity was assessed by functional predictions and frequency in controls. For validation purposes 4 positive controls for variants consisting of previously identified changes were hybridized on the array. As a result of the screening, we detected 44 variants, of which 15 are very likely pathogenic detected in 14 arRP families (14%). Finally, the design of this array can easily be transformed in an equivalent diagnostic system based on targeted enrichment followed by next generation sequencing. PMID:22164218

  9. 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.

  10. Targeted Next-generation Sequencing Reveals Novel EYS Mutations in Chinese Families with Autosomal Recessive Retinitis Pigmentosa

    PubMed Central

    Chen, Xue; Liu, Xiaoxing; Sheng, Xunlun; Gao, Xiang; Zhang, Xiumei; Li, Zili; Li, Huiping; Liu, Yani; Rong, Weining; Zhao, Kanxing; Zhao, Chen

    2015-01-01

    EYS mutations demonstrate great genotypic and phenotypic varieties, and are one of the major causes for patients with autosomal recessive retinitis pigmentosa (ARRP). Here, we aim to determine the genetic lesions with phenotypic correlations in two Chinese families with ARRP. Medical histories and ophthalmic documentations were obtained from all participants from the two pedigrees. Targeted next-generation sequencing (NGS) on 189 genes was performed to screen for RP causative mutations in the two families. Two biallelic mutations in EYS, p.[R164*];[C2139Y] and p.[W2640*];[F2954S], were identified in the two families, respectively. EYS p.R164* and p.F2954S are novel alleles associated with RP, while p.C2139Y and p.W2640* are known mutations. Crystal structure modeling on the protein eyes shut homolog encoded by the EYS gene revealed abnormal hydrogen bonds generated by p.C2139Y and p.F2954S, which would likely affect the solubility and cause significant structural changes of the two mutated proteins. In conclusion, our study expands the genotypic spectrums for EYS mutations, and may provide novel insights into the relevant pathogenesis for RP. We also demonstrate targeted NGS approach as a valuable tool for genetic diagnosis. PMID:25753737

  11. Recessive loss-of-function mutations in AP4S1 cause mild fever-sensitive seizures, developmental delay and spastic paraplegia through loss of AP-4 complex assembly

    PubMed Central

    Hardies, Katia; May, Patrick; Djémié, Tania; Tarta-Arsene, Oana; Deconinck, Tine; Craiu, Dana; Helbig, Ingo; Suls, Arvid; Balling, Rudy; Weckhuysen, Sarah; De Jonghe, Peter; Hirst, Jennifer; Afawi, Zaid; Barisic, Nina; Baulac, Stéphanie; Caglayan, Hande; Depienne, Christel; De Kovel, Carolien G.F.; Dimova, Petia; Guerrero-López, Rosa; Guerrini, Renzo; Hjalgrim, Helle; Hoffman-Zacharska, Dorota; Jahn, Johanna; Klein, Karl Martin; Koeleman, Bobby P.C.; Leguern, Eric; Lehesjoki, Anna-Elina; Lemke, Johannes; Lerche, Holger; Marini, Carla; Muhle, Hiltrud; Rosenow, Felix; Serratosa, Jose M.; Møller, Rikke S.; Stephani, Ulrich; Striano, Pasquale; Talvik, Tiina; Von Spiczak, Sarah; Weber, Yvonne; Zara, Federico

    2015-01-01

    We report two siblings with infantile onset seizures, severe developmental delay and spastic paraplegia, in whom whole-genome sequencing revealed compound heterozygous mutations in the AP4S1 gene, encoding the σ subunit of the adaptor protein complex 4 (AP-4). The effect of the predicted loss-of-function variants (p.Gln46Profs*9 and p.Arg97*) was further investigated in a patient's fibroblast cell line. We show that the premature stop mutations in AP4S1 result in a reduction of all AP-4 subunits and loss of AP-4 complex assembly. Recruitment of the AP-4 accessory protein tepsin, to the membrane was also abolished. In retrospect, the clinical phenotype in the family is consistent with previous reports of the AP-4 deficiency syndrome. Our study reports the second family with mutations in AP4S1 and describes the first two patients with loss of AP4S1 and seizures. We further discuss seizure phenotypes in reported patients, highlighting that seizures are part of the clinical manifestation of the AP-4 deficiency syndrome. We also hypothesize that endosomal trafficking is a common theme between heritable spastic paraplegia and some inherited epilepsies. PMID:25552650

  12. Recessive loss-of-function mutations in AP4S1 cause mild fever-sensitive seizures, developmental delay and spastic paraplegia through loss of AP-4 complex assembly.

    PubMed

    Hardies, Katia; May, Patrick; Djémié, Tania; Tarta-Arsene, Oana; Deconinck, Tine; Craiu, Dana; Helbig, Ingo; Suls, Arvid; Balling, Rudy; Weckhuysen, Sarah; De Jonghe, Peter; Hirst, Jennifer

    2015-04-15

    We report two siblings with infantile onset seizures, severe developmental delay and spastic paraplegia, in whom whole-genome sequencing revealed compound heterozygous mutations in the AP4S1 gene, encoding the σ subunit of the adaptor protein complex 4 (AP-4). The effect of the predicted loss-of-function variants (p.Gln46Profs*9 and p.Arg97*) was further investigated in a patient's fibroblast cell line. We show that the premature stop mutations in AP4S1 result in a reduction of all AP-4 subunits and loss of AP-4 complex assembly. Recruitment of the AP-4 accessory protein tepsin, to the membrane was also abolished. In retrospect, the clinical phenotype in the family is consistent with previous reports of the AP-4 deficiency syndrome. Our study reports the second family with mutations in AP4S1 and describes the first two patients with loss of AP4S1 and seizures. We further discuss seizure phenotypes in reported patients, highlighting that seizures are part of the clinical manifestation of the AP-4 deficiency syndrome. We also hypothesize that endosomal trafficking is a common theme between heritable spastic paraplegia and some inherited epilepsies.

  13. A compound heterozygote of novel and recurrent DTDST mutations results in a novel intermediate phenotype of Desbuquois dysplasia, diastrophic dysplasia, and recessive form of multiple epiphyseal dysplasia.

    PubMed

    Miyake, Atsushi; Nishimura, Gen; Futami, Toru; Ohashi, Hirofumi; Chiba, Kazuhiro; Toyama, Yoshiaki; Furuichi, Tatsuya; Ikegawa, Shiro

    2008-01-01

    Diastrophic dysplasia sulfate transporter (DTDST) is required for synthesis of sulfated proteoglycans in cartilage, and its loss-of-function mutations result in recessively inherited chondrodysplasias. The 40 or so DTDST mutations reported to date cause a group of disorders termed the diastrophic dysplasia (DTD) group. The group ranges from the mildest recessive form of multiple epiphyseal dysplasia (r-MED) through the most common DTD to perinatally lethal atelosteogenesis type II and achondrogenesis 1B. Furthermore, the relationship between DTDST mutations, their sulfate transport function, and disease phenotypes has been described. Here we report a girl with DTDST mutations: a compound heterozygote of a novel p.T266I mutation and a recurrent p.DeltaV340 mutation commonly found in severe phenotypes of the DTD group. In infancy, the girl presented with skeletal manifestations reminiscent of Desbuquois dysplasia, another recessively inherited chondrodysplasia, the mutations of which have never been identified. Her phenotype evolved with age into an intermediate phenotype between r-MED and DTD. Considering her clinical phenotypes and known phenotypes of p.DeltaV340, p.T266I was predicted to be responsible for mild phenotypes of the DTD group. Our results further extend the phenotypic spectrum of DTDST mutations, adding Desbuquois dysplasia to the list of differential diagnosis of the DTD group. PMID:18553123

  14. Exome Sequencing Identifies Biallelic MSH3 Germline Mutations as a Recessive Subtype of Colorectal Adenomatous Polyposis.

    PubMed

    Adam, Ronja; Spier, Isabel; Zhao, Bixiao; Kloth, Michael; Marquez, Jonathan; Hinrichsen, Inga; Kirfel, Jutta; Tafazzoli, Aylar; Horpaopan, Sukanya; Uhlhaas, Siegfried; Stienen, Dietlinde; Friedrichs, Nicolaus; Altmüller, Janine; Laner, Andreas; Holzapfel, Stefanie; Peters, Sophia; Kayser, Katrin; Thiele, Holger; Holinski-Feder, Elke; Marra, Giancarlo; Kristiansen, Glen; Nöthen, Markus M; Büttner, Reinhard; Möslein, Gabriela; Betz, Regina C; Brieger, Angela; Lifton, Richard P; Aretz, Stefan

    2016-08-01

    In ∼30% of families affected by colorectal adenomatous polyposis, no germline mutations have been identified in the previously implicated genes APC, MUTYH, POLE, POLD1, and NTHL1, although a hereditary etiology is likely. To uncover further genes with high-penetrance causative mutations, we performed exome sequencing of leukocyte DNA from 102 unrelated individuals with unexplained adenomatous polyposis. We identified two unrelated individuals with differing compound-heterozygous loss-of-function (LoF) germline mutations in the mismatch-repair gene MSH3. The impact of the MSH3 mutations (c.1148delA, c.2319-1G>A, c.2760delC, and c.3001-2A>C) was indicated at the RNA and protein levels. Analysis of the diseased individuals' tumor tissue demonstrated high microsatellite instability of di- and tetranucleotides (EMAST), and immunohistochemical staining illustrated a complete loss of nuclear MSH3 in normal and tumor tissue, confirming the LoF effect and causal relevance of the mutations. The pedigrees, genotypes, and frequency of MSH3 mutations in the general population are consistent with an autosomal-recessive mode of inheritance. Both index persons have an affected sibling carrying the same mutations. The tumor spectrum in these four persons comprised colorectal and duodenal adenomas, colorectal cancer, gastric cancer, and an early-onset astrocytoma. Additionally, we detected one unrelated individual with biallelic PMS2 germline mutations, representing constitutional mismatch-repair deficiency. Potentially causative variants in 14 more candidate genes identified in 26 other individuals require further workup. In the present study, we identified biallelic germline MSH3 mutations in individuals with a suspected hereditary tumor syndrome. Our data suggest that MSH3 mutations represent an additional recessive subtype of colorectal adenomatous polyposis. PMID:27476653

  15. Autosomal Recessive Disorder Otospondylomegaepiphyseal Dysplasia Is Associated with Loss-of-Function Mutations in the COL11A2 Gene

    PubMed Central

    Melkoniemi, MiiaÂ; Brunner, Han G.Â; Manouvrier, SylvieÂ; Hennekam, RaoulÂ; Superti-Furga, AndreaÂ; Kääriäinen, HelenaÂ; Pauli, Richard M.Â; van Essen, TonÂ; Warman, Matthew L.Â; Bonaventure, JackyÂ; Miny, PeterÂ; Ala-Kokko, LeenaÂ

    2000-01-01

    Summary Otospondylomegaepiphyseal dysplasia (OSMED) is an autosomal recessive skeletal dysplasia accompanied by severe hearing loss. The phenotype overlaps that of the autosomal dominant disorders—Stickler and Marshall syndromes—but can be distinguished by disproportionately short limbs, severe hearing loss, and lack of ocular involvement. In one family with OSMED, a homozygous Gly→Arg substitution has been described in COL11A2, which codes for the α2 chain of type XI collagen. We report seven further families with OSMED. All affected individuals had a remarkably similar phenotype: profound sensorineural hearing loss, skeletal dysplasia with limb shortening and large epiphyses, cleft palate, an extremely flat face, hypoplasia of the mandible, a short nose with anteverted nares, and a flat nasal bridge. We screened affected individuals for mutations in COL11A2 and found different mutations in each family. Individuals from four families, including three with consanguineous parents, were homozygous for mutations. Individuals from three other families, in whom parents were nonconsanguineous, were compound heterozygous. Of the 10 identified mutations, 9 are predicted to cause premature termination of translation, and 1 is predicted to cause an in-frame deletion. We conclude that the OSMED phenotype is highly homogenous and results from homozygosity or compound heterozygosity for COL11A2 mutations, most of which are predicted to cause complete absence of α2(XI) chains. PMID:10677296

  16. 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.

  17. Expansion load: recessive mutations and the role of standing genetic variation.

    PubMed

    Peischl, Stephan; Excoffier, Laurent

    2015-05-01

    Expanding populations incur a mutation burden - the so-called expansion load. Previous studies of expansion load have focused on codominant mutations. An important consequence of this assumption is that expansion load stems exclusively from the accumulation of new mutations occurring in individuals living at the wave front. Using individual-based simulations, we study here the dynamics of standing genetic variation at the front of expansions, and its consequences on mean fitness if mutations are recessive. We find that deleterious genetic diversity is quickly lost at the front of the expansion, but the loss of deleterious mutations at some loci is compensated by an increase of their frequencies at other loci. The frequency of deleterious homozygotes therefore increases along the expansion axis, whereas the average number of deleterious mutations per individual remains nearly constant across the species range. This reveals two important differences to codominant models: (i) mean fitness at the front of the expansion drops much faster if mutations are recessive, and (ii) mutation load can increase during the expansion even if the total number of deleterious mutations per individual remains constant. We use our model to make predictions about the shape of the site frequency spectrum at the front of range expansion, and about correlations between heterozygosity and fitness in different parts of the species range. Importantly, these predictions provide opportunities to empirically validate our theoretical results. We discuss our findings in the light of recent results on the distribution of deleterious genetic variation across human populations and link them to empirical results on the correlation of heterozygosity and fitness found in many natural range expansions.

  18. The R402Q tyrosinase variant does not cause autosomal recessive ocular albinism.

    PubMed

    Oetting, William S; Pietsch, Jacy; Brott, Marcia J; Savage, Sarah; Fryer, James P; Summers, C Gail; King, Richard A

    2009-03-01

    Mutations in the gene for tyrosinase, the key enzyme in melanin synthesis, are responsible for oculocutaneous albinism type 1, and more than 100 mutations of this gene have been identified. The c.1205G > A variant of the tyrosinase gene (rs1126809) predicts p.R402Q and expression studies show thermolabile enzyme activity for the variant protein. The Q402 allele has been associated with autosomal recessive ocular albinism when it is in trans with a tyrosinase gene mutation associated with oculocutaneous albinism type 1. We have identified 12 families with oculocutaneous albinism type 1 that exhibit segregation of the c.1205G > A variant with a known pathologic mutation on the homologous chromosome, and demonstrate no genetic association between autosomal recessive oculocutaneous albinism and the Q402 variant. We conclude that the codon 402 variant of the tyrosinase gene is not associated with albinism. PMID:19208379

  19. Gene Editing for the Efficient Correction of a Recurrent COL7A1 Mutation in Recessive Dystrophic Epidermolysis Bullosa Keratinocytes

    PubMed Central

    Chamorro, Cristina; Mencía, Angeles; Almarza, David; Duarte, Blanca; Büning, Hildegard; Sallach, Jessica; Hausser, Ingrid; Del Río, Marcela; Larcher, Fernando; Murillas, Rodolfo

    2016-01-01

    Clonal gene therapy protocols based on the precise manipulation of epidermal stem cells require highly efficient gene-editing molecular tools. We have combined adeno-associated virus (AAV)-mediated delivery of donor template DNA with transcription activator-like nucleases (TALE) expressed by adenoviral vectors to address the correction of the c.6527insC mutation in the COL7A1 gene, causing recessive dystrophic epidermolysis bullosa in a high percentage of Spanish patients. After transduction with these viral vectors, high frequencies of homology-directed repair were found in clones of keratinocytes derived from a recessive dystrophic epidermolysis bullosa (RDEB) patient homozygous for the c.6527insC mutation. Gene-edited clones recovered the expression of the COL7A1 transcript and collagen VII protein at physiological levels. In addition, treatment of patient keratinocytes with TALE nucleases in the absence of a donor template DNA resulted in nonhomologous end joining (NHEJ)-mediated indel generation in the vicinity of the c.6527insC mutation site in a large proportion of keratinocyte clones. A subset of these indels restored the reading frame of COL7A1 and resulted in abundant, supraphysiological expression levels of mutant or truncated collagen VII protein. Keratinocyte clones corrected both by homology-directed repair (HDR) or NHEJ were used to regenerate skin displaying collagen VII in the dermo-epidermal junction. PMID:27045209

  20. Whole exome sequencing identifies three recessive FIG4 mutations in an apparently dominant pedigree with Charcot-Marie-Tooth disease.

    PubMed

    Menezes, Manoj P; Waddell, Leigh; Lenk, Guy M; Kaur, Simranpreet; MacArthur, Daniel G; Meisler, Miriam H; Clarke, Nigel F

    2014-08-01

    Charcot-Marie-Tooth disease (CMT) is genetically heterogeneous and classification based on motor nerve conduction velocity and inheritance is used to direct genetic testing. With the less common genetic forms of CMT, identifying the causative genetic mutation by Sanger sequencing of individual genes can be time-consuming and costly. Next-generation sequencing technologies show promise for clinical testing in diseases where a similar phenotype is caused by different genes. We report the unusual occurrence of CMT4J, caused by mutations in FIG4, in a apparently dominant pedigree. The affected proband and her mother exhibit different disease severities associated with different combinations of compound heterozygous FIG4 mutations, identified by whole exome sequencing. The proband was also shown to carry a de novo nonsense mutation in the dystrophin gene, which may contribute to her more severe phenotype. This study is a cautionary reminder that in families with two generations affected, explanations other than dominant inheritance are possible, such as recessive inheritance due to three mutations segregating in the family. It also emphasises the advantages of next-generation sequencing approaches that screen multiple CMT genes at once for patients in whom the common genes have been excluded.

  1. Mutations in IMPG1 Cause Vitelliform Macular Dystrophies

    PubMed Central

    Manes, Gaël; Meunier, Isabelle; Avila-Fernández, Almudena; Banfi, Sandro; Le Meur, Guylène; Zanlonghi, Xavier; Corton, Marta; Simonelli, Francesca; Brabet, Philippe; Labesse, Gilles; Audo, Isabelle; Mohand-Said, Saddek; Zeitz, Christina; Sahel, José-Alain; Weber, Michel; Dollfus, Hélène; Dhaenens, Claire-Marie; Allorge, Delphine; De Baere, Elfride; Koenekoop, Robert K.; Kohl, Susanne; Cremers, Frans P.M.; Hollyfield, Joe G.; Sénéchal, Audrey; Hebrard, Maxime; Bocquet, Béatrice; Ayuso García, Carmen; Hamel, Christian P.

    2013-01-01

    Vitelliform macular dystrophies (VMD) are inherited retinal dystrophies characterized by yellow, round deposits visible upon fundus examination and encountered in individuals with juvenile Best macular dystrophy (BMD) or adult-onset vitelliform macular dystrophy (AVMD). Although many BMD and some AVMD cases harbor mutations in BEST1 or PRPH2, the underlying genetic cause remains unknown for many affected individuals. In a large family with autosomal-dominant VMD, gene mapping and whole-exome sequencing led to the identification of a c.713T>G (p.Leu238Arg) IMPG1 mutation, which was subsequently found in two other families with autosomal-dominant VMD and the same phenotype. IMPG1 encodes the SPACR protein, a component of the rod and cone photoreceptor extracellular matrix domains. Structural modeling indicates that the p.Leu238Arg substitution destabilizes the conserved SEA1 domain of SPACR. Screening of 144 probands who had various forms of macular dystrophy revealed three other IMPG1 mutations. Two individuals from one family affected by autosomal-recessive VMD were homozygous for the splice-site mutation c.807+1G>T, and two from another family were compound heterozygous for the mutations c.461T>C (p.Leu154Pro) and c.1519C>T (p.Arg507∗). Most cases had a normal or moderately decreased electrooculogram Arden ratio. We conclude that IMPG1 mutations cause both autosomal-dominant and -recessive forms of VMD, thus indicating that impairment of the interphotoreceptor matrix might be a general cause of VMD. PMID:23993198

  2. Case Report: Whole exome sequencing reveals a novel frameshift deletion mutation p.G2254fs in COL7A1 associated with autosomal recessive dystrophic epidermolysis bullosa

    PubMed Central

    Karuthedath Vellarikkal, Shamsudheen; Jayarajan, Rijith; Verma, Ankit; Nair, Sreelata; Ravi, Rowmika; Senthivel, Vigneshwar; Sivasubbu, Sridhar; Scaria, Vinod

    2016-01-01

    Dystrophic epidermolysis bullosa simplex (DEB) is a phenotypically diverse inherited skin fragility disorder. It is majorly manifested by appearance of epidermal bullae upon friction caused either by physical or environmental trauma. The phenotypic manifestations also include appearance of milia, scarring all over the body and nail dystrophy. DEB can be inherited in a recessive or dominant form and the recessive form of DEB (RDEB) is more severe. In the present study, we identify a novel p.G2254fs mutation in COL7A1 gene causing a sporadic case of RDEB by whole exome sequencing (WES). Apart from adding a novel frameshift Collagen VII mutation to the repertoire of known mutations reported in the disease, to the best of our knowledge, this is the first report of a genetically characterized case of DEB from India. PMID:27408687

  3. Thomsen or Becker myotonia? A novel autosomal recessive nonsense mutation in the CLCN1 gene associated with a mild phenotype.

    PubMed

    Gurgel-Giannetti, Juliana; Senkevics, Adriano S; Zilbersztajn-Gotlieb, Dinorah; Yamamoto, Lydia U; Muniz, Viviane P; Pavanello, Rita C M; Oliveira, Acary B; Zatz, Mayana; Vainzof, Mariz

    2012-02-01

    We describe a large Brazilian consanguineous kindred with 3 clinically affected patients with a Thomsen myotonia phenotype. They carry a novel homozygous nonsense mutation in the CLCN1 gene (K248X). None of the 6 heterozygote carriers show any sign of myotonia on clinical evaluation or electromyography. These findings confirm the autosomal recessive inheritance of the novel mutation in this family, as well as the occurrence of phenotypic variability in the autosomal recessive forms of myotonia.

  4. Mapping of mutation causing Friedreich's ataxia to human chromosome 9.

    PubMed

    Chamberlain, S; Shaw, J; Rowland, A; Wallis, J; South, S; Nakamura, Y; von Gabain, A; Farrall, M; Williamson, R

    1988-07-21

    Friedreich's ataxia is an autosomal recessive disease with progressive degeneration of the central and peripheral nervous system. The biochemical abnormality underlying the disorder has not been identified. Prompted by the success in localizing the mutations causing Duchenne muscular dystrophy, Huntington's disease and cystic fibrosis, we have undertaken molecular genetic linkage studies to determine the chromosomal site of the Friedreich's ataxia mutation as an initial step towards the isolation and characterization of the defective gene. We report the assignment of the gene mutation for this disorder to chromosome 9p22-CEN by genetic linkage to an anonymous DNA marker MCT112 and the interferon-beta gene probe. In contrast to the clinical variation seen for the disorder, no evidence of genetic heterogeneity is observed.

  5. Alternative splicing modifies the effect of mutations in COL11A1 and results in recessive type 2 Stickler syndrome with profound hearing loss

    PubMed Central

    Richards, Allan J; Fincham, Gregory S; McNinch, Annie; Hill, David; Poulson, Arabella V; Castle, Bruce; Lees, Melissa M; Moore, Anthony T; Scott, John D; Snead, Martin P

    2013-01-01

    Background Stickler syndromes types 1, 2 and 3 are usually dominant disorders caused by mutations in the genes COL2A1, COL11A1 and COL11A2 that encode the fibrillar collagens types II and XI present in cartilage and vitreous. Rare recessive forms of Stickler syndrome exist that are due to mutations in genes encoding type IX collagen (COL9A1 type 4 Stickler syndrome and COL9A2 type 5 Stickler syndrome). Recently, recessive mutations in the COL11A1 gene have been demonstrated to result in fibrochondrogenesis, a much more severe skeletal dysplasia, which is often lethal. Here we demonstrate that some mutations in COL11A1 are recessive, modified by alternative splicing and result in type 2 Stickler syndrome rather than fibrochondrogenesis. Methods Patients referred to the national Stickler syndrome diagnostic service for England, UK were assessed clinically and subsequently sequenced for mutations in COL11A1. Additional in silico and functional studies to assess the effect of sequence variants on pre-mRNA processing and collagen structure were performed. Results In three different families, heterozygous COL11A1 biallelic null, null/missense or silent/missense mutations, were found. They resulted in a recessive form of type 2 Stickler syndrome characterised by particularly profound hearing loss and are clinically distinct from the recessive types 4 and 5 variants of Stickler syndrome. One mutant allele in each family is capable of synthesising a normal α1(XI) procollagen molecule, via variable pre-mRNA processing. Conclusion This new variant has important implications for molecular diagnosis and counselling families with type 2 Stickler syndrome. PMID:23922384

  6. Autosomal recessive cerebellar ataxia of adult onset due to STUB1 mutations.

    PubMed

    Depondt, Chantal; Donatello, Simona; Simonis, Nicolas; Rai, Myriam; van Heurck, Roxane; Abramowicz, Marc; D'Hooghe, Marc; Pandolfo, Massimo

    2014-05-13

    Autosomal recessive ataxias affect about 1 person in 20,000. Friedreich ataxia accounts for one-third of the cases in Caucasians; the others are due to a growing list of very rare molecular defects, including mild forms of metabolic diseases. In nearly 50%, the genetic cause remains undetermined.

  7. Mitochondrial Hsp60 Chaperonopathy Causes an Autosomal-Recessive Neurodegenerative Disorder Linked to Brain Hypomyelination and Leukodystrophy

    PubMed Central

    Magen, Daniella; Georgopoulos, Costa; Bross, Peter; Ang, Debbie; Segev, Yardena; Goldsher, Dorit; Nemirovski, Alexandra; Shahar, Eli; Ravid, Sarit; Luder, Anthony; Heno, Bayan; Gershoni-Baruch, Ruth; Skorecki, Karl; Mandel, Hanna

    2008-01-01

    Hypomyelinating leukodystrophies (HMLs) are disorders involving aberrant myelin formation. The prototype of primary HMLs is the X-linked Pelizaeus-Merzbacher disease (PMD) caused by mutations in PLP1. Recently, homozygous mutations in GJA12 encoding connexin 47 were found in patients with autosomal-recessive Pelizaeus-Merzbacher-like disease (PMLD). However, many patients of both genders with PMLD carry neither PLP1 nor GJA12 mutations. We report a consanguineous Israeli Bedouin kindred with clinical and radiological findings compatible with PMLD, in which linkage to PLP1 and GJA12 was excluded. Using homozygosity mapping and mutation analysis, we have identified a homozygous missense mutation (D29G) not previously described in HSPD1, encoding the mitochondrial heat-shock protein 60 (Hsp60) in all affected individuals. The D29G mutation completely segregates with the disease-associated phenotype. The pathogenic effect of D29G on Hsp60-chaperonin activity was verified by an in vivo E. coli complementation assay, which demonstrated compromised ability of the D29G-Hsp60 mutant protein to support E. coli survival, especially at high temperatures. The disorder, which we have termed MitCHAP-60 disease, can be distinguished from spastic paraplegia 13 (SPG13), another Hsp60-associated autosomal-dominant neurodegenerative disorder, by its autosomal-recessive inheritance pattern, as well as by its early-onset, profound cerebral involvement and lethality. Our findings suggest that Hsp60 defects can cause neurodegenerative pathologies of varying severity, not previously suspected on the basis of the SPG13 phenotype. These findings should help to clarify the important role of Hsp60 in myelinogenesis and neurodegeneration. PMID:18571143

  8. Mitochondrial hsp60 chaperonopathy causes an autosomal-recessive neurodegenerative disorder linked to brain hypomyelination and leukodystrophy.

    PubMed

    Magen, Daniella; Georgopoulos, Costa; Bross, Peter; Ang, Debbie; Segev, Yardena; Goldsher, Dorit; Nemirovski, Alexandra; Shahar, Eli; Ravid, Sarit; Luder, Anthony; Heno, Bayan; Gershoni-Baruch, Ruth; Skorecki, Karl; Mandel, Hanna

    2008-07-01

    Hypomyelinating leukodystrophies (HMLs) are disorders involving aberrant myelin formation. The prototype of primary HMLs is the X-linked Pelizaeus-Merzbacher disease (PMD) caused by mutations in PLP1. Recently, homozygous mutations in GJA12 encoding connexin 47 were found in patients with autosomal-recessive Pelizaeus-Merzbacher-like disease (PMLD). However, many patients of both genders with PMLD carry neither PLP1 nor GJA12 mutations. We report a consanguineous Israeli Bedouin kindred with clinical and radiological findings compatible with PMLD, in which linkage to PLP1 and GJA12 was excluded. Using homozygosity mapping and mutation analysis, we have identified a homozygous missense mutation (D29G) not previously described in HSPD1, encoding the mitochondrial heat-shock protein 60 (Hsp60) in all affected individuals. The D29G mutation completely segregates with the disease-associated phenotype. The pathogenic effect of D29G on Hsp60-chaperonin activity was verified by an in vivo E. coli complementation assay, which demonstrated compromised ability of the D29G-Hsp60 mutant protein to support E. coli survival, especially at high temperatures. The disorder, which we have termed MitCHAP-60 disease, can be distinguished from spastic paraplegia 13 (SPG13), another Hsp60-associated autosomal-dominant neurodegenerative disorder, by its autosomal-recessive inheritance pattern, as well as by its early-onset, profound cerebral involvement and lethality. Our findings suggest that Hsp60 defects can cause neurodegenerative pathologies of varying severity, not previously suspected on the basis of the SPG13 phenotype. These findings should help to clarify the important role of Hsp60 in myelinogenesis and neurodegeneration.

  9. Phenotypes of Recessive Pediatric Cataract in a Cohort of Children with Identified Homozygous Gene Mutations (An American Ophthalmological Society Thesis)

    PubMed Central

    Khan, Arif O.; Aldahmesh, Mohammed A.; Alkuraya, Fowzan S.

    2015-01-01

    Purpose: To assess for phenotype-genotype correlations in families with recessive pediatric cataract and identified gene mutations. Methods: Retrospective review (2004 through 2013) of 26 Saudi Arabian apparently nonsyndromic pediatric cataract families referred to one of the authors (A.O.K.) and for which recessive gene mutations were identified. Results: Fifteen different homozygous recessive gene mutations were identified in the 26 consanguineous families; two genes and five families are novel to this study. Ten families had a founder CRYBB1 deletion (all with bilateral central pulverulent cataract), two had the same missense mutation in CRYAB (both with bilateral juvenile cataract with marked variable expressivity), and two had different mutations in FYCO1 (both with bilateral posterior capsular abnormality). The remaining 12 families each had mutations in 12 different genes (CRYAA, CRYBA1, AKR1E2, AGK, BFSP2, CYP27A1, CYP51A1, EPHA2, GCNT2, LONP1, RNLS, WDR87) with unique phenotypes noted for CYP27A1 (bilateral juvenile fleck with anterior and/or posterior capsular cataract and later cerebrotendinous xanthomatosis), EPHA2 (bilateral anterior persistent fetal vasculature), and BFSP2 (bilateral flecklike with cloudy cortex). Potential carrier signs were documented for several families. Conclusions: In this recessive pediatric cataract case series most identified genes are noncrystallin. Recessive pediatric cataract phenotypes are generally nonspecific, but some notable phenotypes are distinct and associated with specific gene mutations. Marked variable expressivity can occur from a recessive missense CRYAB mutation. Genetic analysis of apparently isolated pediatric cataract can sometimes uncover mutations in a syndromic gene. Some gene mutations seem to be associated with apparent heterozygous carrier signs. PMID:26622071

  10. A recessive Nav1.4 mutation underlies congenital myasthenic syndrome with periodic paralysis

    PubMed Central

    Habbout, Karima; Poulin, Hugo; Rivier, François; Giuliano, Serena; Sternberg, Damien; Fontaine, Bertrand; Eymard, Bruno; Morales, Raul Juntas; Echenne, Bernard; King, Louise; Hanna, Michael G.; Männikkö, Roope; Chahine, Mohamed; Nicole, Sophie

    2016-01-01

    Objective: To determine the molecular basis of a complex phenotype of congenital muscle weakness observed in an isolated but consanguineous patient. Methods: The proband was evaluated clinically and neurophysiologically over a period of 15 years. Genetic testing of candidate genes was performed. Functional characterization of the candidate mutation was done in mammalian cell background using whole cell patch clamp technique. Results: The proband had fatigable muscle weakness characteristic of congenital myasthenic syndrome with acute and reversible attacks of most severe muscle weakness as observed in periodic paralysis. We identified a novel homozygous SCN4A mutation (p.R1454W) linked to this recessively inherited phenotype. The p.R1454W substitution induced an important enhancement of fast and slow inactivation, a slower recovery for these inactivated states, and a frequency-dependent regulation of Nav1.4 channels in the heterologous expression system. Conclusion: We identified a novel loss-of-function mutation of Nav1.4 that leads to a recessive phenotype combining clinical symptoms and signs of congenital myasthenic syndrome and periodic paralysis, probably by decreasing channel availability for muscle action potential genesis at the neuromuscular junction and propagation along the sarcolemma. PMID:26659129

  11. Mutations in the gene encoding the alpha subunit of the rod cGMP-gated channel in autosomal recessive retinitis pigmentosa.

    PubMed

    Dryja, T P; Finn, J T; Peng, Y W; McGee, T L; Berson, E L; Yau, K W

    1995-10-24

    Mutations in the genes encoding two proteins of the retinal rod phototransduction cascade, opsin and the beta subunit of rod cGMP phosphodiesterase, cause retinitis pigmentosa (RP) in some families. Here we report defects in a third member of this biochemical pathway in still other patients with this disease. We screened 94 unrelated patients with autosomal dominant RP and 173 unrelated patients with autosomal recessive RP for mutations in the gene encoding the alpha subunit of the rod cGMP-gated cation channel. Five mutant sequences cosegregated with disease among four unrelated families with autosomal recessive RP. Two of these were nonsense mutations early in the reading frame (Glu76End and Lys139End) and one was a deletion encompassing most if not all of the transcriptional unit; these three alleles would not be expected to encode a functional channel. The remaining two mutations were a missense mutation (Ser316Phe) and a frameshift [Arg654(1-bp del)] mutation truncating the last 32 aa in the C terminus. The latter two mutations were expressed in vitro and found to encode proteins that were predominantly retained inside the cell instead of being targeted to the plasma membrane. We conclude that the absence or paucity of functional cGMP-gated cation channels in the plasma membrane is deleterious to rod photoreceptors and is an uncommon cause of RP.

  12. Mutations in TNK2 in severe autosomal recessive infantile onset epilepsy.

    PubMed

    Hitomi, Yuki; Heinzen, Erin L; Donatello, Simona; Dahl, Hans-Henrik; Damiano, John A; McMahon, Jacinta M; Berkovic, Samuel F; Scheffer, Ingrid E; Legros, Benjamin; Rai, Myriam; Weckhuysen, Sarah; Suls, Arvid; De Jonghe, Peter; Pandolfo, Massimo; Goldstein, David B; Van Bogaert, Patrick; Depondt, Chantal

    2013-09-01

    We identified a small family with autosomal recessive, infantile onset epilepsy and intellectual disability. Exome sequencing identified a homozygous missense variant in the gene TNK2, encoding a brain-expressed tyrosine kinase. Sequencing of the coding region of TNK2 in 110 patients with a similar phenotype failed to detect further homozygote or compound heterozygote mutations. Pathogenicity of the variant is supported by the results of our functional studies, which demonstrated that the variant abolishes NEDD4 binding to TNK2, preventing its degradation after epidermal growth factor stimulation. Definitive proof of pathogenicity will require confirmation in unrelated patients.

  13. Mutations in TNK2 in severe autosomal recessive infantile-onset epilepsy

    PubMed Central

    Hitomi, Yuki; Heinzen, Erin L.; Donatello, Simona; Dahl, Hans-Henrik; Damiano, John A.; McMahon, Jacinta M.; Berkovic, Samuel F.; Scheffer, Ingrid E.; Legros, Benjamin; Rai, Myriam; Weckhuysen, Sarah; Suls, Arvid; De Jonghe, Peter; Pandolfo, Massimo; Goldstein, David B.; Van Bogaert, Patrick; Depondt, Chantal

    2013-01-01

    We identified a small family with autosomal recessive, infantile-onset epilepsy and intellectual disability. Exome sequencing identified a homozygous missense variant in the gene TNK2, encoding a brain-expressed tyrosine kinase. Sequencing of the coding region of TNK2 in 110 patients with a similar phenotype failed to detect further homozygote or compound heterozygote mutations. Pathogenicity of the variant is supported by the results of our functional studies, which demonstrated that the variant abolishes NEDD4 binding to TNK2, preventing its degradation after epidermal growth factor stimulation. Definitive proof of pathogenicity will require confirmation in unrelated patients. PMID:23686771

  14. LAMB3 mutations causing autosomal-dominant amelogenesis imperfecta.

    PubMed

    Kim, J W; Seymen, F; Lee, K E; Ko, J; Yildirim, M; Tuna, E B; Gencay, K; Shin, T J; Kyun, H K; Simmer, J P; Hu, J C-C

    2013-10-01

    Amelogenesis imperfecta (AI) can be either isolated or part of a larger syndrome. Junctional epidermolysis bullosa (JEB) is a collection of autosomal-recessive disorders featuring AI associated with skin fragility and other symptoms. JEB is a recessive syndrome usually caused by mutations in both alleles of COL17A1, LAMA3, LAMB3, or LAMC2. In rare cases, heterozygous carriers in JEB kindreds display enamel malformations in the absence of skin fragility (isolated AI). We recruited two kindreds with autosomal-dominant amelogenesis imperfecta (ADAI) characterized by generalized severe enamel hypoplasia with deep linear grooves and pits. Whole-exome sequencing of both probands identified novel heterozygous mutations in the last exon of LAMB3 that likely truncated the protein. The mutations perfectly segregated with the enamel defects in both families. In Family 1, an 8-bp deletion (c.3446_3453del GACTGGAG) shifted the reading frame (p.Gly 1149Glufs*8). In Family 2, a single nucleotide substitution (c.C3431A) generated an in-frame translation termination codon (p.Ser1144*). We conclude that enamel formation is particularly sensitive to defects in hemidesmosome/basement-membrane complexes and that syndromic and non-syndromic forms of AI can be etiologically related. PMID:23958762

  15. Mutations in CDK5RAP2 cause Seckel syndrome

    PubMed Central

    Yigit, Gökhan; Brown, Karen E; Kayserili, Hülya; Pohl, Esther; Caliebe, Almuth; Zahnleiter, Diana; Rosser, Elisabeth; Bögershausen, Nina; Uyguner, Zehra Oya; Altunoglu, Umut; Nürnberg, Gudrun; Nürnberg, Peter; Rauch, Anita; Li, Yun; Thiel, Christian Thomas; Wollnik, Bernd

    2015-01-01

    Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152. PMID:26436113

  16. Mutations in CDK5RAP2 cause Seckel syndrome.

    PubMed

    Yigit, Gökhan; Brown, Karen E; Kayserili, Hülya; Pohl, Esther; Caliebe, Almuth; Zahnleiter, Diana; Rosser, Elisabeth; Bögershausen, Nina; Uyguner, Zehra Oya; Altunoglu, Umut; Nürnberg, Gudrun; Nürnberg, Peter; Rauch, Anita; Li, Yun; Thiel, Christian Thomas; Wollnik, Bernd

    2015-09-01

    Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152.

  17. Mutations in CDK5RAP2 cause Seckel syndrome.

    PubMed

    Yigit, Gökhan; Brown, Karen E; Kayserili, Hülya; Pohl, Esther; Caliebe, Almuth; Zahnleiter, Diana; Rosser, Elisabeth; Bögershausen, Nina; Uyguner, Zehra Oya; Altunoglu, Umut; Nürnberg, Gudrun; Nürnberg, Peter; Rauch, Anita; Li, Yun; Thiel, Christian Thomas; Wollnik, Bernd

    2015-09-01

    Seckel syndrome is a heterogeneous, autosomal recessive disorder marked by prenatal proportionate short stature, severe microcephaly, intellectual disability, and characteristic facial features. Here, we describe the novel homozygous splice-site mutations c.383+1G>C and c.4005-9A>G in CDK5RAP2 in two consanguineous families with Seckel syndrome. CDK5RAP2 (CEP215) encodes a centrosomal protein which is known to be essential for centrosomal cohesion and proper spindle formation and has been shown to be causally involved in autosomal recessive primary microcephaly. We establish CDK5RAP2 as a disease-causing gene for Seckel syndrome and show that loss of functional CDK5RAP2 leads to severe defects in mitosis and spindle organization, resulting in cells with abnormal nuclei and centrosomal pattern, which underlines the important role of centrosomal and mitotic proteins in the pathogenesis of the disease. Additionally, we present an intriguing case of possible digenic inheritance in Seckel syndrome: A severely affected child of nonconsanguineous German parents was found to carry heterozygous mutations in CDK5RAP2 and CEP152. This finding points toward a potential additive genetic effect of mutations in CDK5RAP2 and CEP152. PMID:26436113

  18. Periaxin mutations cause a broad spectrum of demyelinating neuropathies.

    PubMed

    Takashima, Hiroshi; Boerkoel, Cornelius F; De Jonghe, Peter; Ceuterick, Chantal; Martin, Jean-Jacques; Voit, Thomas; Schröder, J-Michael; Williams, Anna; Brophy, Peter J; Timmerman, Vincent; Lupski, James R

    2002-06-01

    Previous studies have demonstrated that apparent loss-of-function mutations in the periaxin gene cause autosomal recessive Dejerine-Sottas neuropathy or severe demyelinating Charcot-Marie-Tooth disease. In this report, we extend the associated phenotypes with the identification of two additional families with novel periaxin gene mutations (C715X and R82fsX96) and provide detailed neuropathology. Each patient had marked sensory involvement; two siblings with a homozygous C715X mutation had much worse sensory impairment than motor impairment. Despite early disease onset, these siblings with the C715X mutation had relatively slow disease progression and adult motor impairment typical of classic demyelinating Charcot-Marie-Tooth neuropathy. In contrast, a patient with the homozygous R82fsX96 mutation had a disease course consistent with Dejerine-Sottas neuropathy. The neuropathology of patients in both families was remarkable for demyelination, onion bulb and occasional tomacula formation with focal myelin thickening, abnormalities of the paranodal myelin loops, and focal absence of paranodal septate-like junctions between the terminal loops and axon. Our study indicates a prominent sensory neuropathy resulting from periaxin gene mutations and suggests a role for the carboxyl terminal domain of the periaxin protein. PMID:12112076

  19. The search for mutations in the gene for the beta subunit of the cGMP phosphodiesterase (PDEB) in patients with autosomal recessive retinitis pigmentosa

    SciTech Connect

    Riess, O.; Weber, B.; Hayden, M.R. ); Noerremoelle, A. ); Musarella, M.A. )

    1992-10-01

    The finding of a mutation in the beta subunit of the cyclic GMP (cGMP) phosphodiesterase gene causing retinal degeneration in mice (the Pdeb gene) prompted a search for disease-causing mutations in the human phosphodiesterase gene (PDEB gene) in patients with retinitis pigmentosa. All 22 exons including 196 bp of the 5[prime] region of the PDEB gene have been assessed for mutations by using single-strand conformational polymorphism analysis in 14 patients from 13 unrelated families with autosomal recessive retinitis pigmentosa (ARRP). No disease-causing mutations were found in this group of affected individuals of seven different ancestries. However, a frequent intronic and two exonic polymorphisms (Leu[sup 489][yields]Gln and Gly[sup 842][yields]Gly) were identified. Segregation analysis using these polymorphic sites excludes linkage of ARRP to the PDEB gene in a family with two affected children. 43 refs., 3 figs., 2 tabs.

  20. Novel Deletion of SERPINF1 Causes Autosomal Recessive Osteogenesis Imperfecta Type VI in Two Brazilian Families

    PubMed Central

    Moldenhauer Minillo, Renata; Sobreira, Nara; de Fatima de Faria Soares, Maria; Jurgens, Julie; Ling, Hua; Hetrick, Kurt N.; Doheny, Kimberly F.; Valle, David; Brunoni, Decio; Alvarez Perez, Ana B.

    2014-01-01

    Autosomal recessive osteogenesis imperfecta (OI) accounts for 10% of all OI cases, and, currently, mutations in 10 genes (CRTAP, LEPRE1, PPIB, SERPINH1, FKBP10, SERPINF1, SP7, BMP1, TMEM38B, and WNT1) are known to be responsible for this form of the disease. PEDF is a secreted glycoprotein of the serpin superfamily that maintains bone homeostasis and regulates osteoid mineralization, and it is encoded by SERPINF1, currently associated with OI type VI (MIM 172860). Here, we report a consanguineous Brazilian family in which multiple individuals from at least 4 generations are affected with a severe form of OI, and we also report an unrelated individual from the same small city in Brazil with a similar but more severe phenotype. In both families the same homozygous SERPINF1 19-bp deletion was identified which is not known in the literature yet. We described intra- and interfamilial clinical and radiological phenotypic variability of OI type VI caused by the same homozygous SERPINF1 19-bp deletion and suggest a founder effect. Furthermore, the SERPINF1 genotypes/phenotypes reported so far in the literature are reviewed. PMID:25565926

  1. Proteins linked to autosomal dominant and autosomal recessive disorders harbor characteristic rare missense mutation distribution patterns.

    PubMed

    Turner, Tychele N; Douville, Christopher; Kim, Dewey; Stenson, Peter D; Cooper, David N; Chakravarti, Aravinda; Karchin, Rachel

    2015-11-01

    The role of rare missense variants in disease causation remains difficult to interpret. We explore whether the clustering pattern of rare missense variants (MAF < 0.01) in a protein is associated with mode of inheritance. Mutations in genes associated with autosomal dominant (AD) conditions are known to result in either loss or gain of function, whereas mutations in genes associated with autosomal recessive (AR) conditions invariably result in loss-of-function. Loss-of-function mutations tend to be distributed uniformly along protein sequence, whereas gain-of-function mutations tend to localize to key regions. It has not previously been ascertained whether these patterns hold in general for rare missense mutations. We consider the extent to which rare missense variants are located within annotated protein domains and whether they form clusters, using a new unbiased method called CLUstering by Mutation Position. These approaches quantified a significant difference in clustering between AD and AR diseases. Proteins linked to AD diseases exhibited more clustering of rare missense mutations than those linked to AR diseases (Wilcoxon P = 5.7 × 10(-4), permutation P = 8.4 × 10(-4)). Rare missense mutation in proteins linked to either AD or AR diseases was more clustered than controls (1000G) (Wilcoxon P = 2.8 × 10(-15) for AD and P = 4.5 × 10(-4) for AR, permutation P = 3.1 × 10(-12) for AD and P = 0.03 for AR). The differences in clustering patterns persisted even after removal of the most prominent genes. Testing for such non-random patterns may reveal novel aspects of disease etiology in large sample studies. PMID:26246501

  2. Mutations in the PDE6B gene in autosomal recessive retinitis pigmentosa

    SciTech Connect

    Danciger, M.; Blaney, J.; Gao, Y.Q.; Zhao, D.Y.

    1995-11-01

    We have studied 24 small families with presumed autosomal recessive inheritance of retinitis pigmentosa by a combination of haplotype analysis and exon screening. Initial analysis of the families was made with a dinucleotide repeat polymorphism adjacent to the gene for rod cGMP-phosphodiesterase (PDE6B). This was followed by denaturing gradient gel electrophoresis (DGGE) and single-strand conformation polymorphism electrophoresis (SSCPE) of the 22 exons and a portion of the 5{prime} untranslated region of the PDE6B gene in the probands of each family in which the PDE6B locus could not be ruled out from segregating with disease. Two probands were found with compound heterozygous mutations: Gly576Asp and His620(1-bp del) mutations were present in one proband, and a Lys706X null mutation and an AG to AT splice acceptor site mutation in intron 2 were present in the other. Only the affecteds of each of the two families carried both corresponding mutations. 29 refs., 3 figs., 1 tab.

  3. Mutations in PYCR1 cause cutis laxa with progeroid features.

    PubMed

    Reversade, Bruno; Escande-Beillard, Nathalie; Dimopoulou, Aikaterini; Fischer, Björn; Chng, Serene C; Li, Yun; Shboul, Mohammad; Tham, Puay-Yoke; Kayserili, Hülya; Al-Gazali, Lihadh; Shahwan, Monzer; Brancati, Francesco; Lee, Hane; O'Connor, Brian D; Schmidt-von Kegler, Mareen; Merriman, Barry; Nelson, Stanley F; Masri, Amira; Alkazaleh, Fawaz; Guerra, Deanna; Ferrari, Paola; Nanda, Arti; Rajab, Anna; Markie, David; Gray, Mary; Nelson, John; Grix, Arthur; Sommer, Annemarie; Savarirayan, Ravi; Janecke, Andreas R; Steichen, Elisabeth; Sillence, David; Hausser, Ingrid; Budde, Birgit; Nürnberg, Gudrun; Nürnberg, Peter; Seemann, Petra; Kunkel, Désirée; Zambruno, Giovanna; Dallapiccola, Bruno; Schuelke, Markus; Robertson, Stephen; Hamamy, Hanan; Wollnik, Bernd; Van Maldergem, Lionel; Mundlos, Stefan; Kornak, Uwe

    2009-09-01

    Autosomal recessive cutis laxa (ARCL) describes a group of syndromal disorders that are often associated with a progeroid appearance, lax and wrinkled skin, osteopenia and mental retardation. Homozygosity mapping in several kindreds with ARCL identified a candidate region on chromosome 17q25. By high-throughput sequencing of the entire candidate region, we detected disease-causing mutations in the gene PYCR1. We found that the gene product, an enzyme involved in proline metabolism, localizes to mitochondria. Altered mitochondrial morphology, membrane potential and increased apoptosis rate upon oxidative stress were evident in fibroblasts from affected individuals. Knockdown of the orthologous genes in Xenopus and zebrafish led to epidermal hypoplasia and blistering that was accompanied by a massive increase of apoptosis. Our findings link mutations in PYCR1 to altered mitochondrial function and progeroid changes in connective tissues.

  4. A GLRA1 null mutation in recessive hyperekplexia challenges the functional role of glycine receptors

    SciTech Connect

    Brune, W.; Saul, M.; Becker, C.M.

    1996-05-01

    Dominant missense mutations in the human glycine receptor (GlyR) {alpha}1 subunit gene (GLRA1) give rise to hereditary hyperekplexia. These mutations impair agonist affinities and change conductance states of expressed mutant channels, resulting in a partial loss of function. In a recessive case of hyperekplexia, we found a deletion of exons 1-6 of the GLRA1 gene. Born to consanguineous parents, the affected child is homozygous for this GLRA1{sup null} allele consistent with a complete loss of gene function. The child displayed exaggerated startle responses and pronounced head-retraction jerks reflecting a disinhibition of vestigial brain-stem reflexes. In contrast, proprio- and exteroceptive inhibition of muscle activity previously correlated to glycinergic mechanisms were not affected. This case demonstrates that, in contrast to the lethal effect of a null allele in the recessive mouse mutant oscillator (Glra1{sup spd-ot}), the loss of the GlyR {alpha}1 subunit is effectively compensated in man. 38 refs.

  5. Homozygous STIL Mutation Causes Holoprosencephaly and Microcephaly in Two Siblings

    PubMed Central

    Mouden, Charlotte; de Tayrac, Marie; Dubourg, Christèle; Rose, Sophie; Carré, Wilfrid; Hamdi-Rozé, Houda; Babron, Marie-Claude; Akloul, Linda; Héron-Longe, Bénédicte; Odent, Sylvie; Dupé, Valérie; Giet, Régis; David, Véronique

    2015-01-01

    Holoprosencephaly (HPE) is a frequent congenital malformation of the brain characterized by impaired forebrain cleavage and midline facial anomalies. Heterozygous mutations in 14 genes have been identified in HPE patients that account for only 30% of HPE cases, suggesting the existence of other HPE genes. Data from homozygosity mapping and whole-exome sequencing in a consanguineous Turkish family were combined to identify a homozygous missense mutation (c.2150G>A; p.Gly717Glu) in STIL, common to the two affected children. STIL has a role in centriole formation and has previously been described in rare cases of microcephaly. Rescue experiments in U2OS cells showed that the STIL p.Gly717Glu mutation was not able to fully restore the centriole duplication failure following depletion of endogenous STIL protein indicating the deleterious role of the mutation. In situ hybridization experiments using chick embryos demonstrated that expression of Stil was in accordance with a function during early patterning of the forebrain. It is only the second time that a STIL homozygous mutation causing a recessive form of HPE was reported. This result also supports the genetic heterogeneity of HPE and increases the panel of genes to be tested for HPE diagnosis. PMID:25658757

  6. [Advances in hereditary hearing loss caused by TMC1 mutations].

    PubMed

    Wu, Kaiwen; Wang, Hongyang; Wang, Qiuju

    2016-03-01

    Hearing loss is the most frequent sensorineural disorder worldwild, among which about 50% are caused by genetic factors. TMC1 is one of the common genes causing hereditary hearing loss. TMC1 mutations can cause pre-lingual profound/severe autosomal recessive (DFNB7/11) and post-lingual progressive autosomal dominant (DFNA36) non-syndromic hearing loss. Murine models studies show that TMC1, 2 are expressed in cochlea inner and outer hair cells and maintain normal mechanoelectrical transduction (MET) functions of the hair cells. A growing number of evidence indicate that TMC1, 2 are components of the MET complex. It is necessary to definite the precise distribution and exact function of TMC1, 2, because it is important to understand the regulating mechanism of auditory function. PMID:27033582

  7. Expanding the Clinical Spectrum of SPG11 Gene Mutations in Recessive Hereditary Spastic Paraplegia with Thin Corpus Callosum

    PubMed Central

    Aleem, Alice Abdel; Abu-Shahba, Nourhan; Swistun, Dominika; Silhavy, Jennifer; Bielas, Stephanie L.; Sattar, Shifteh; Gleeson, Joseph G.; Zaki, Maha

    2011-01-01

    Hereditary spastic paraplegia (HSP) represents a large group of neurological disorders characterized by progressive spasticity of the lower limbs. One subtype of HSP shows an autosomal recessive form of inheritance with this corpus callosum (ARHSP-TCC), and displays genetic heterogeneity with four known loci. We identified a consanguineous Egyptian family with five affected individuals with ARHSP-TCC. We found linkage to the SPG11 locus and identified a novel homozygous p.Q498X stop codon mutation in exon 7 in the SPG11 gene encoding Spatacsin. Cognitive impairment and polyneuropathy, reported as frequent in SPG11, were not evident. This family supports the importance of SPG11 as a frequent cause for ARHSP-TCC, and expands the clinic SPG11 spectrum. PMID:20971220

  8. Recessive RYR1 mutations in a patient with severe congenital nemaline myopathy with ophthalomoplegia identified through massively parallel sequencing.

    PubMed

    Kondo, Eri; Nishimura, Takafumi; Kosho, Tomoki; Inaba, Yuji; Mitsuhashi, Satomi; Ishida, Takefumi; Baba, Atsushi; Koike, Kenichi; Nishino, Ichizo; Nonaka, Ikuya; Furukawa, Toru; Saito, Kayoko

    2012-04-01

    Nemaline myopathy (NM) is a group of congenital myopathies, characterized by the presence of distinct rod-like inclusions "nemaline bodies" in the sarcoplasm of skeletal muscle fibers. To date, ACTA1, NEB, TPM3, TPM2, TNNT1, and CFL2 have been found to cause NM. We have identified recessive RYR1 mutations in a patient with severe congenital NM, through high-throughput screening of congenital myopathy/muscular dystrophy-related genes using massively parallel sequencing with target gene capture. The patient manifested fetal akinesia, neonatal severe hypotonia with muscle weakness, respiratory insufficiency, swallowing disturbance, and ophthalomoplegia. Skeletal muscle histology demonstrated nemaline bodies and small type 1 fibers, but without central cores or minicores. Congenital myopathies, a molecularly, histopathologically, and clinically heterogeneous group of disorders are considered to be a good candidate for massively parallel sequencing. PMID:22407809

  9. Mutation Spectrum of EYS in Spanish Patients with Autosomal Recessive Retinitis Pigmentosa

    PubMed Central

    Barragán, Isabel; Borrego, Salud; Pieras, Juan Ignacio; Pozo, María González-del; Santoyo, Javier; Ayuso, Carmen; Baiget, Montserrat; Millan, José M; Mena, Marcela; El-Aziz, Mai M Abd; Audo, Isabelle; Zeitz, Christina; Littink, Karin W; Dopazo, Joaquín; Bhattacharya, Shomi S; Antiñolo, Guillermo

    2010-01-01

    Retinitis pigmentosa (RP) is a heterogeneous group of inherited retinal dystrophies characterised ultimately by the loss of photoreceptor cells. We have recently identified a new gene (EYS) encoding an ortholog of Drosophila spacemaker (spam) as a commonly mutated gene in autosomal recessive RP. In the present study, we report the identification of 73 sequence variations in EYS, of which 28 are novel. Of these, 42.9% (12/28) are very likely pathogenic, 17.9% (5/28) are possibly pathogenic, whereas 39.3% (11/28) are SNPs. In addition, we have detected 3 pathogenic changes previously reported in other populations. We are also presenting the characterisation of EYS homologues in different species, and a detailed analysis of the EYS domains, with the identification of an interesting novel feature: a putative coiled-coil domain. Majority of the mutations in the arRP patients have been found within the domain structures of EYS. The minimum observed prevalence of distinct EYS mutations in our group of patients is of 15.9% (15/94), confirming a major involvement of EYS in the pathogenesis of arRP in the Spanish population. Along with the detection of three recurrent mutations in Caucasian population, our hypothesis of EYS being the first prevalent gene in arRP has been reinforced in the present study. © 2010 Wiley-Liss, Inc. PMID:21069908

  10. 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

  11. Homozygous Nonsense Mutations in TWIST2 Cause Setleis Syndrome

    PubMed Central

    Tukel, Turgut; Šošić, Dražen; Al-Gazali, Lihadh I.; Erazo, Mónica; Casasnovas, Jose; Franco, Hector L.; Richardson, James A.; Olson, Eric N.; Cadilla, Carmen L.; Desnick, Robert J.

    2010-01-01

    The focal facial dermal dysplasias (FFDDs) are a group of inherited developmental disorders in which the characteristic diagnostic feature is bitemporal scar-like lesions that resemble forceps marks. To date, the genetic defects underlying these ectodermal dysplasias have not been determined. To identify the gene defect causing autosomal-recessive Setleis syndrome (type III FFDD), homozygosity mapping was performed with genomic DNAs from five affected individuals and 26 members of the consanguineous Puerto Rican (PR) family originally described by Setleis and colleagues. Microsatellites D2S1397 and D2S2968 were homozygous in all affected individuals, mapping the disease locus to 2q37.3. Haplotype analyses of additional markers in the PR family and a consanguineous Arab family further limited the disease locus to ∼3 Mb between D2S2949 and D2S2253. Of the 29 candidate genes in this region, the bHLH transcription factor, TWIST2, was initially sequenced on the basis of its known involvement in murine facial development. Homozygous TWIST2 nonsense mutations, c.324C>T and c.486C>T, were identified in the affected members of the Arab and PR families, respectively. Characterization of the expressed mutant proteins, p.Q65X and p.Q119X, by electrophoretic mobility shift assays and immunoblot analyses indicated that they were truncated and unstable. Notably, Setleis syndrome patients and Twist2 knockout mice have similar facial features, indicating the gene's conserved role in mammalian development. Although human TWIST2 and TWIST1 encode highly homologous bHLH transcription factors, the finding that TWIST2 recessive mutations cause an FFDD and dominant TWIST1 mutations cause Saethre-Chotzen craniocynostosis suggests that they function independently in skin and bone development. PMID:20691403

  12. Novel Lethal Form of Congenital Hypopituitarism Associated With the First Recessive LHX4 Mutation

    PubMed Central

    Gregory, L. C.; Humayun, K. N.; Turton, J. P. G.; McCabe, M. J.; Rhodes, S. J.

    2015-01-01

    Background: LHX4 encodes a member of the LIM-homeodomain family of transcription factors that is required for normal development of the pituitary gland. To date, only incompletely penetrant heterozygous mutations in LHX4 have been described in patients with variable combined pituitary hormone deficiencies. Objective/Hypothesis: To report a unique family with a novel recessive variant in LHX4 associated with a lethal form of congenital hypopituitarism that was identified through screening a total of 97 patients. Method: We screened 97 unrelated patients with combined pituitary hormone deficiency, including 65% with an ectopic posterior pituitary, for variants in the LHX4 gene using Sanger sequencing. Control databases (1000 Genomes, dbSNP, Exome Variant Server, ExAC Browser) were consulted upon identification of variants. Results: We identified the first novel homozygous missense variant (c.377C>T, p.T126M) in two deceased male patients of Pakistani origin with severe panhypopituitarism associated with anterior pituitary aplasia and posterior pituitary ectopia. Both were born small for gestational age with a small phallus, undescended testes, and mid-facial hypoplasia. The parents' first-born child was a female with mid-facial hypoplasia (DNA was unavailable). Despite rapid commencement of hydrocortisone and T4 in the brothers, all three children died within the first week of life. The LHX4(p.T126M) variant is located within the LIM2 domain, in a highly conserved location. The absence of homozygosity for the variant in over 65 000 controls suggests that it is likely to be responsible for the phenotype. Conclusion: We report, for the first time to our knowledge, a novel homozygous mutation in LHX4 associated with a lethal phenotype, implying that recessive mutations in LHX4 may be incompatible with life. PMID:25871839

  13. Congenital Recessive Methemoglobinemia Revealed in Adulthood: Description of a New Mutation in Cytochrome b5 Reductase Gene.

    PubMed

    Forestier, Alexandra; Pissard, Serge; Cretet, Justine; Mambie, Adeline; Pascal, Laurent; Cliquennois, Manuel; Cambier, Nathalie; Rose, Christian

    2015-01-01

    Methemoglobinemia can be acquired (oxidizing drugs or chemicals products) or inherited either by mutations affecting globin chains [M hemoglobins (M Hbs)] or by defects in the enzymatic system involved in the reduction of spontaneous Hb oxidation: nicotinamide adenine dinucleotide (NADH)-cytochrome b5 reductase. It is encoded by the CYB5R3 gene: there are two phenotypes of autosomal recessive congenital methemoglobinemia, in type II CYB5R deficiency is generalized and affects all cells, leading to an early onset, whereas in type I, the enzyme deficiency is restricted to erythrocytes, usually discovered in infancy but not exclusively. We report a new case of methemoglobinemia discovered in a patient from Bahrain who exhibited an unknown dyspnea at the age of 37 years without trigger events or oxidizing products. We discovered a new mutation in the CYB5R3 gene: exon 9, codon 266 (delGAG) (GLU) (CYB5R3: c.726_729delGAG) in the homozygous state. Appearance of methemoglobinemia in an adult usually suggests an acquired cause but our case illustrated that it could also reveal a type I mutation of cytochrome b5 reductase. PMID:26291966

  14. Mutations in POMGNT1 cause non-syndromic retinitis pigmentosa.

    PubMed

    Xu, Mingchu; Yamada, Takeyuki; Sun, Zixi; Eblimit, Aiden; Lopez, Irma; Wang, Feng; Manya, Hiroshi; Xu, Shan; Zhao, Li; Li, Yumei; Kimchi, Adva; Sharon, Dror; Sui, Ruifang; Endo, Tamao; Koenekoop, Robert K; Chen, Rui

    2016-04-15

    A growing number of human diseases have been linked to defects in protein glycosylation that affects a wide range of organs. Among them, O-mannosylation is an unusual type of protein glycosylation that is largely restricted to the muscular and nerve system. Consistently, mutations in genes involved in the O-mannosylation pathway result in infantile-onset, severe developmental defects involving skeleton muscle, brain and eye, such as the muscle-eye-brain disease (MIM no. 253280). However, the functional importance of O-mannosylation in these tissues at later stages remains largely unknown. In our study, we have identified recessive mutations in POMGNT1, which encodes an essential component in O-mannosylation pathway, in three unrelated families with autosomal recessive retinitis pigmentosa (RP), but without extraocular involvement. Enzymatic assay of these mutant alleles demonstrate that they greatly reduce the POMGNT1 enzymatic activity and are likely to be hypomorphic. Immunohistochemistry shows that POMGNT1 is specifically expressed in photoreceptor basal body. Taken together, our work identifies a novel disease-causing gene for RP and indicates that proper protein O-mannosylation is not only essential for early organ development, but also important for maintaining survival and function of the highly specialized retinal cells at later stages. PMID:26908613

  15. Functional Basis of Three New Recessive Mutations of Slow Skeletal Muscle Troponin T Found in Non-Amish TNNT1 Nemaline Myopathies.

    PubMed

    Amarasinghe, Chinthaka; Hossain, M Moazzem; Jin, J-P

    2016-08-16

    Troponin T (TnT) is the tropomyosin (Tm)-binding and thin filament-anchoring subunit of troponin and plays a central role in striated muscle contraction. A nonsense mutation in exon 11 of the TNNT1 gene encoding slow skeletal muscle troponin T (ssTnT) truncating the polypeptide chain at Glu(180) causes a lethal recessive nemaline myopathy (NM) in the Amish (ANM). More TNNT1 NM mutations have been reported recently with similar recessive phenotypes. A nonsense mutation in exon 9 causes truncation at Ser(108), and a splicing site mutation causes truncation at Leu(203). Another splicing site mutation causes an internal deletion of the 39 exon 8-encoded amino acids. We engineered and characterized these ssTnT mutants to demonstrate that the Ser(108) truncation exhibits a Tm binding affinity lower than that of the ANM Glu(180) truncation, indicating a partial loss of Tm-binding site 1. Despite the presence of Tm-binding sites 1 and 2, ssTnT truncated at Leu(203) binds Tm with decreased affinity, consistent with its recessive NM phenotype and the requirement of troponin complex formation for high-affinity binding of TnT to Tm. The exon 8-deleted ssTnT has a partial loss of Tm-binding site 1 but retains high-affinity Tm-binding site 2. However, exon 8-deleted ssTnT exhibits a dramatically diminished Tm binding affinity, indicating a long-range conformational effect of this middle region deletion. Predicted from the TnT structure-function relationship, removal of the N-terminal variable region partially rescued this negative impact. These novel findings lay a foundation for understanding the pathogenesis of TNNT1 myopathies and provide insights into the development of targeted treatment. PMID:27429059

  16. Recessive ACTA1 variant causes congenital muscular dystrophy with rigid spine.

    PubMed

    O'Grady, Gina L; Best, Heather A; Oates, Emily C; Kaur, Simranpreet; Charlton, Amanda; Brammah, Susan; Punetha, Jaya; Kesari, Akanchha; North, Kathryn N; Ilkovski, Biljana; Hoffman, Eric P; Clarke, Nigel F

    2015-06-01

    Variants in ACTA1, which encodes α-skeletal actin, cause several congenital myopathies, most commonly nemaline myopathy. Autosomal recessive variants comprise approximately 10% of ACTA1 myopathy. All recessive variants reported to date have resulted in loss of skeletal α-actin expression from muscle and severe weakness from birth. Targeted next-generation sequencing in two brothers with congenital muscular dystrophy with rigid spine revealed homozygous missense variants in ACTA1. Skeletal α-actin expression was preserved in these patients. This report expands the clinical and histological phenotype of ACTA1 disease to include congenital muscular dystrophy with rigid spine and dystrophic features on muscle biopsy. This represents a new class of recessive ACTA1 variants, which do not abolish protein expression. PMID:25182138

  17. Dental Abnormalities Caused by Novel Compound Heterozygous CTSK Mutations.

    PubMed

    Xue, Y; Wang, L; Xia, D; Li, Q; Gao, S; Dong, M; Cai, T; Shi, S; He, L; Hu, K; Mao, T; Duan, X

    2015-05-01

    Cathepsin K (CTSK) is an important protease responsible for degrading type I collagen, osteopontin, and other bone matrix proteins. The mutations in the CTSK gene can cause pycnodysostosis (OMIM 265800), a rare autosomal recessive bone dysplasia. Patients with pycnodysostosis have been reported to present specific dental abnormalities; however, whether these dental abnormalities are related to dysfunctional CTSK has never been reported. Here we investigated the histologic changes of cementum and alveolar bone in a pycnodysostosis patient, caused by novel compound heterozygous mutations in the CTSK gene (c.87 G>A p.W29X and c.848 A>G p.Y283C). The most impressive manifestations in tooth were extensive periradicular high-density clumps with unclear periodontal space by orthopantomography examination and micro-computed tomography scanning analysis. Hematoxylin/eosin and toluidine blue staining and atomic force microscopy analysis showed that the cementum became significantly thickened, softened, and full of cementocytes. The disorganized bone structure was the main character of alveolar bone. The p.W29X mutation may represent the loss-of-function allele with an earlier termination codon in the precursor CTSK polypeptide. Residue Y283 is highly conserved among papain-like cysteine proteases. Three-dimensional structure modeling analysis found that the loss of the hydroxybenzene residue in the Y283C mutation would interrupt the hydrogen network and possibly affect the self-cleavage of the CTSK enzyme. Furthermore, p.Y283C mutation did not affect the mRNA and protein levels of overexpressed CTSK in COS-7 system but did reduce CTSK enzyme activity. In conclusion, the histologic and ultrastructural changes of cementum and alveolar bone might be affected by CTSK mutation via reduction of its enzyme activity (clinical trial registration: ChiCTR-TNC-10000876).

  18. Case report: vitamin D-dependent rickets type 1 caused by a novel CYP27B1 mutation.

    PubMed

    Füchtbauer, Laila; Brusgaard, Klaus; Ledaal, Pål; Frost, Morten; Frederiksen, Anja L

    2015-12-01

    Vitamin D-dependent rickets type 1 VDDR-1 is a recessive inherited disorder with impaired activation of vitamin D, caused by mutations in CYP27B1. We present long-time follow-up of a case with a novel mutation including high-resolution peripheral quantitative computed tomography of the bone. Adequate treatment resulted in a normalized phenotype.

  19. IARS mutation causes prenatal death in Japanese Black cattle.

    PubMed

    Hirano, Takashi; Matsuhashi, Tamako; Takeda, Kenji; Hara, Hiromi; Kobayashi, Naohiko; Kita, Kazuo; Sugimoto, Yoshikazu; Hanzawa, Kei

    2016-09-01

    Isoleucyl-tRNA synthetase (IARS) c.235G > C (p.V79L) is a causative mutation for a recessive disease called IARS disorder in Japanese black cattle. The disease is involved in weak calf syndrome and is characterized by low birth weight, weakness and poor suckling. The gestation period is often slightly extended, implying that intrauterine growth is retarded. In a previous analysis of 2597 artificial insemination (AI) procedures, we suggested that the IARS mutation might contribute toward an increase in the incidence of prenatal death. In this study, we extended this analysis to better clarify the association between the IARS mutation and prenatal death. The IARS genotypes of 92 animals resulting from crosses between carrier (G/C) × G/C were 27 normal (G/G), 55 G/C and 10 affected animals (C/C) (expected numbers: 23, 46 and 23, respectively). Compared to the expected numbers, there were significantly fewer affected animals in this population (P < 0.05), suggesting that more than half of the affected embryos died prenatally. When the number of AI procedures examined was increased to 11 580, the frequency of re-insemination after G/C × G/C insemination was significantly higher at 61-140 days (P < 0.001). The findings suggested that the homozygous IARS mutation not only causes calf death, but also embryonic or fetal death. PMID:27229878

  20. [A case of autosomal recessive hypomyelinating leukodystrophy without GJA12 mutation presenting a novel phenotype].

    PubMed

    Ishikawa, Tomoko; Sato, Kimiko; Shimazaki, Rie; Goto, Katsumasa; Matsuda, Takao; Ishiura, Hiroyuki

    2010-01-01

    A 50-year-old woman, who had consanguineous parents, developed gait disturbance at age 3, and revealed nystagmus, cerebellar ataxia, peripheral neuropathy, and spastic tetraparesis. She admitted to our hospital at age 14, and the symptoms progressed very slowly. MRI of this case at age 45 showed a remarkable, diffuse hypomyelination of the cerebrum. Her older sister who already deceased at age 16 showed neurological symptoms similar to this case. The patient was found to have no proteolipid protein-1 gene duplications and deletions and base substitution. Her symptoms were considered to be different from those of typical HLD2, 3, 4 and 5. She carried no GJA12 mutations. These facts suggested that this disease is a novel, autosomal recessive hypomyelinating leukodystrophy. PMID:20120347

  1. One Novel Frameshift Mutation on Exon 64 of COL7A1 Gene in an Iranian Individual Suffering Recessive Dystrophic Epidermolysis Bullosa.

    PubMed

    Khaniani, Mahmoud Shekari; Sohrabi, Nasrin; Derakhshan, Neda Mansoori; Derakhshan, Sima Mansoori

    2015-01-01

    Recessive dystrophic epidermolysis bullosa (RDEB) is an extremely rare subtype of bullous dermatosis caused by the COL7A1 gene mutation. After genomic DNA extraction from the peripheral blood sample of all subjects (3 pedigree members and 3 unrelated control individuals), COL7A1 gene screening was performed by PCR amplification and direct DNA sequencing of all of the coding exons and flanking intronic regions. Genetic analysis of the COL7A1 gene in an affected individual revealed a novel mutation: c.5493delG (p.K1831Nfs*10) in exon 64 of the COL7A1 gene in homozygous state. This mutation was not discovered in 3 unrelated Iranian control individuals. These data suggest that c.5493delG may influence the phenotype of RDEB. The result of this case report contributes to the expanding database on COL7A1 mutations.

  2. Mutations in GRHL2 result in an autosomal-recessive ectodermal Dysplasia syndrome.

    PubMed

    Petrof, Gabriela; Nanda, Arti; Howden, Jake; Takeichi, Takuya; McMillan, James R; Aristodemou, Sophia; Ozoemena, Linda; Liu, Lu; South, Andrew P; Pourreyron, Celine; Dafou, Dimitra; Proudfoot, Laura E; Al-Ajmi, Hejab; Akiyama, Masashi; McLean, W H Irwin; Simpson, Michael A; Parsons, Maddy; McGrath, John A

    2014-09-01

    Grainyhead-like 2, encoded by GRHL2, is a member of a highly conserved family of transcription factors that play essential roles during epithelial development. Haploinsufficiency for GRHL2 has been implicated in autosomal-dominant deafness, but mutations have not yet been associated with any skin pathology. We investigated two unrelated Kuwaiti families in which a total of six individuals have had lifelong ectodermal defects. The clinical features comprised nail dystrophy or nail loss, marginal palmoplantar keratoderma, hypodontia, enamel hypoplasia, oral hyperpigmentation, and dysphagia. In addition, three individuals had sensorineural deafness, and three had bronchial asthma. Taken together, the features were consistent with an unusual autosomal-recessive ectodermal dysplasia syndrome. Because of consanguinity in both families, we used whole-exome sequencing to search for novel homozygous DNA variants and found GRHL2 mutations common to both families: affected subjects in one family were homozygous for c.1192T>C (p.Tyr398His) in exon 9, and subjects in the other family were homozygous for c.1445T>A (p.Ile482Lys) in exon 11. Immortalized keratinocytes (p.Ile482Lys) showed altered cell morphology, impaired tight junctions, adhesion defects, and cytoplasmic translocation of GRHL2. Whole-skin transcriptomic analysis (p.Ile482Lys) disclosed changes in genes implicated in networks of cell-cell and cell-matrix adhesion. Our clinical findings of an autosomal-recessive ectodermal dysplasia syndrome provide insight into the role of GRHL2 in skin development, homeostasis, and human disease.

  3. Similar phenotypes caused by mutations in OTOG and OTOGL

    PubMed Central

    Oonk, Anne M.M.; Leijendeckers, Joop M.; Huygen, Patrick L.M.; Schraders, Margit; del Campo, Miguel; del Castillo, Ignacio; Tekin, Mustafa; Feenstra, Ilse; Beynon, Andy J.; Kunst, Henricus P.M.; Snik, Ad F.M.; Kremer, Hannie; Admiraal, Ronald J.C.; Pennings, Ronald J.E.

    2013-01-01

    Objectives recently, OTOG and OTOGL were identified as human deafness genes. Currently, only four families are known to have autosomal recessive hearing loss based on mutations in these genes. Since the two genes code for proteins (otogelin and otogelin-like) that are strikingly similar in structure and localization in the inner ear, this study is focused on characterizing and comparing the hearing loss caused by mutations in these genes. Design To evaluate this type of hearing, an extensive set of audiometric and vestibular examinations was performed in the 13 patients from four families. Results all families show a flat to downsloping configuration of the audiogram with mild to moderate sensorineural hearing loss. Speech recognition scores remain good (>90%). Hearing loss is not significantly different in the four families and the psychophysical test results also do not differ between the families. Vestibular examinations show evidence for vestibular hyporeflexia. Conclusion since otogelin and otogelin-like are localized in the tectorial membrane, one could expect a cochlear conductive hearing loss, as was previously shown in DFNA13 (COL11A2) and DFNA8/12 (TECTA) patients. Results of psychophysical examinations, however, do not support this. Furthermore, the authors can conclude that there are no phenotypic differences between hearing loss based on mutations in OTOG or OTOGL. This phenotype description will facilitate counseling of hearing loss caused by defects in either of these two genes. PMID:24378291

  4. A Mutation in SLC24A1 Implicated in Autosomal-Recessive Congenital Stationary Night Blindness

    PubMed Central

    Riazuddin, S. Amer; Shahzadi, Amber; Zeitz, Christina; Ahmed, Zubair M.; Ayyagari, Radha; Chavali, Venkata R.M.; Ponferrada, Virgilio G.; Audo, Isabelle; Michiels, Christelle; Lancelot, Marie-Elise; Nasir, Idrees A.; Zafar, Ahmad U.; Khan, Shaheen N.; Husnain, Tayyab; Jiao, Xiaodong; MacDonald, Ian M.; Riazuddin, Sheikh; Sieving, Paul A.; Katsanis, Nicholas; Hejtmancik, J. Fielding

    2010-01-01

    Congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder that can be associated with impaired night vision. The last decade has witnessed huge progress in ophthalmic genetics, including the identification of three genes implicated in the pathogenicity of autosomal-recessive CSNB. However, not all patients studied could be associated with mutations in these genes and thus other genes certainly underlie this disorder. Here, we report a large multigeneration family with five affected individuals manifesting symptoms of night blindness. A genome-wide scan localized the disease interval to chromosome 15q, and recombination events in affected individuals refined the critical interval to a 10.41 cM (6.53 Mb) region that harbors SLC24A1, a member of the solute carrier protein superfamily. Sequencing of all the coding exons identified a 2 bp deletion in exon 2: c.1613_1614del, which is predicted to result in a frame shift that leads to premature termination of SLC24A1 (p.F538CfsX23) and segregates with the disorder under an autosomal-recessive model. Expression analysis using mouse ocular tissues shows that Slc24a1 is expressed in the retina around postnatal day 7. In situ and immunohistological studies localized both SLC24A1 and Slc24a1 to the inner segment, outer and inner nuclear layers, and ganglion cells of the retina, respectively. Our data expand the genetic basis of CSNB and highlight the indispensible function of SLC24A1 in retinal function and/or maintenance in humans. PMID:20850105

  5. RTTN Mutations Cause Primary Microcephaly and Primordial Dwarfism in Humans

    PubMed Central

    Shamseldin, Hanan; Alazami, Anas M.; Manning, Melanie; Hashem, Amal; Caluseiu, Oana; Tabarki, Brahim; Esplin, Edward; Schelley, Susan; Innes, A. Micheil; Parboosingh, Jillian S.; Lamont, Ryan; Majewski, Jacek; Bernier, Francois P.; Alkuraya, Fowzan S.

    2015-01-01

    Primary microcephaly is a developmental brain anomaly that results from defective proliferation of neuroprogenitors in the germinal periventricular zone. More than a dozen genes are known to be mutated in autosomal-recessive primary microcephaly in isolation or in association with a more generalized growth deficiency (microcephalic primordial dwarfism), but the genetic heterogeneity is probably more extensive. In a research protocol involving autozygome mapping and exome sequencing, we recruited a multiplex consanguineous family who is affected by severe microcephalic primordial dwarfism and tested negative on clinical exome sequencing. Two candidate autozygous intervals were identified, and the second round of exome sequencing revealed a single intronic variant therein (c.2885+8A>G [p.Ser963∗] in RTTN exon 23). RT-PCR confirmed that this change creates a cryptic splice donor and thus causes retention of the intervening 7 bp of the intron and leads to premature truncation. On the basis of this finding, we reanalyzed the exome file of a second consanguineous family affected by a similar phenotype and identified another homozygous change in RTTN as the likely causal mutation. Combined linkage analysis of the two families confirmed that RTTN maps to the only significant linkage peak. Finally, through international collaboration, a Canadian multiplex family affected by microcephalic primordial dwarfism and biallelic mutation of RTTN was identified. Our results expand the phenotype of RTTN-related disorders, hitherto limited to polymicrogyria, to include microcephalic primordial dwarfism with a complex brain phenotype involving simplified gyration. PMID:26608784

  6. Novel homozygous mutations in the EVC and EVC2 genes in two consanguineous families segregating autosomal recessive Ellis-van Creveld syndrome.

    PubMed

    Aziz, Abdul; Raza, Syed I; Ali, Salman; Ahmad, Wasim

    2016-01-01

    Ellis-van Creveld syndrome (EVC) is a rare developmental disorder characterized by short limbs, short ribs, postaxial polydactyly, dysplastic nails, teeth, oral and cardiac abnormalities. It is caused by biallelic mutations in the EVC or EVC2 gene, separated by 2.6 kb of genomic sequence on chromosome 4p16. In the present study, we have investigated two consanguineous families of Pakistani origin, segregating EVC in autosomal recessive manner. Linkage in the families was established to chromosome 4p16. Subsequently, sequence analysis identified a novel nonsense mutation (p.Trp234*) in exon 8 of the EVC2 gene and 15 bp duplication in exon 14 of the EVC gene in the two families. This further expands the mutations in the EVC or EVC2 genes resulting in the EVC syndrome.

  7. Adaptor protein complex 4 deficiency causes severe autosomal-recessive intellectual disability, progressive spastic paraplegia, shy character, and short stature.

    PubMed

    Abou Jamra, Rami; Philippe, Orianne; Raas-Rothschild, Annick; Eck, Sebastian H; Graf, Elisabeth; Buchert, Rebecca; Borck, Guntram; Ekici, Arif; Brockschmidt, Felix F; Nöthen, Markus M; Munnich, Arnold; Strom, Tim M; Reis, Andre; Colleaux, Laurence

    2011-06-10

    Intellectual disability inherited in an autosomal-recessive fashion represents an important fraction of severe cognitive-dysfunction disorders. Yet, the extreme heterogeneity of these conditions markedly hampers gene identification. Here, we report on eight affected individuals who were from three consanguineous families and presented with severe intellectual disability, absent speech, shy character, stereotypic laughter, muscular hypotonia that progressed to spastic paraplegia, microcephaly, foot deformity, decreased muscle mass of the lower limbs, inability to walk, and growth retardation. Using a combination of autozygosity mapping and either Sanger sequencing of candidate genes or next-generation exome sequencing, we identified one mutation in each of three genes encoding adaptor protein complex 4 (AP4) subunits: a nonsense mutation in AP4S1 (NM_007077.3: c.124C>T, p.Arg42(∗)), a frameshift mutation in AP4B1 (NM_006594.2: c.487_488insTAT, p.Glu163_Ser739delinsVal), and a splice mutation in AP4E1 (NM_007347.3: c.542+1_542+4delGTAA, r.421_542del, p.Glu181Glyfs(∗)20). Adaptor protein complexes (AP1-4) are ubiquitously expressed, evolutionarily conserved heterotetrameric complexes that mediate different types of vesicle formation and the selection of cargo molecules for inclusion into these vesicles. Interestingly, two mutations affecting AP4M1 and AP4E1 have recently been found to cause cerebral palsy associated with severe intellectual disability. Combined with previous observations, these results support the hypothesis that AP4-complex-mediated trafficking plays a crucial role in brain development and functioning and demonstrate the existence of a clinically recognizable syndrome due to deficiency of the AP4 complex. PMID:21620353

  8. Mutations in Twinkle primase-helicase cause Perrault syndrome with neurologic features

    PubMed Central

    Morino, Hiroyuki; Matsuda, Yukiko; Walsh, Tom; Ohsawa, Ryosuke; Newby, Marta; Hiraki-Kamon, Keiko; Kuramochi, Masahito; Lee, Ming K.; Klevit, Rachel E.; Martin, Alan; Maruyama, Hirofumi; King, Mary-Claire

    2014-01-01

    Objective: To identify the genetic cause in 2 families of progressive ataxia, axonal neuropathy, hyporeflexia, and abnormal eye movements, accompanied by progressive hearing loss and ovarian dysgenesis, with a clinical diagnosis of Perrault syndrome. Methods: Whole-exome sequencing was performed to identify causative mutations in the 2 affected sisters in each family. Family 1 is of Japanese ancestry, and family 2 is of European ancestry. Results: In family 1, affected individuals were compound heterozygous for chromosome 10 open reading frame 2 (C10orf2) p.Arg391His and p.Asn585Ser. In family 2, affected individuals were compound heterozygous for C10orf2 p.Trp441Gly and p.Val507Ile. C10orf2 encodes Twinkle, a primase-helicase essential for replication of mitochondrial DNA. Conservation and structural modeling support the causality of the mutations. Twinkle is known also to harbor multiple mutations, nearly all missenses, leading to dominant progressive external ophthalmoplegia type 3 and to recessive mitochondrial DNA depletion syndrome 7, also known as infantile-onset spinocerebellar ataxia. Conclusions: Our study identifies Twinkle mutations as a cause of Perrault syndrome accompanied by neurologic features and expands the phenotypic spectrum of recessive disease caused by mutations in Twinkle. The phenotypic heterogeneity of conditions caused by Twinkle mutations and the genetic heterogeneity of Perrault syndrome call for genomic definition of these disorders. PMID:25355836

  9. Mutations in ANTXR1 Cause GAPO Syndrome

    PubMed Central

    Stránecký, Viktor; Hoischen, Alexander; Hartmannová, Hana; Zaki, Maha S.; Chaudhary, Amit; Zudaire, Enrique; Nosková, Lenka; Barešová, Veronika; Přistoupilová, Anna; Hodaňová, Kateřina; Sovová, Jana; Hůlková, Helena; Piherová, Lenka; Hehir-Kwa, Jayne Y.; de Silva, Deepthi; Senanayake, Manouri P.; Farrag, Sameh; Zeman, Jiří; Martásek, Pavel; Baxová, Alice; Afifi, Hanan H.; St. Croix, Brad; Brunner, Han G.; Temtamy, Samia; Kmoch, Stanislav

    2013-01-01

    The genetic cause of GAPO syndrome, a condition characterized by growth retardation, alopecia, pseudoanodontia, and progressive visual impairment, has not previously been identified. We studied four ethnically unrelated affected individuals and identified homozygous nonsense mutations (c.262C>T [p.Arg88*] and c.505C>T [p.Arg169*]) or splicing mutations (c.1435–12A>G [p.Gly479Phefs*119]) in ANTXR1, which encodes anthrax toxin receptor 1. The nonsense mutations predictably trigger nonsense-mediated mRNA decay, resulting in the loss of ANTXR1. The transcript with the splicing mutation theoretically encodes a truncated ANTXR1 containing a neopeptide composed of 118 unique amino acids in its C terminus. GAPO syndrome’s major phenotypic features, which include dental abnormalities and the accumulation of extracellular matrix, recapitulate those found in Antxr1-mutant mice and point toward an underlying defect in extracellular-matrix regulation. Thus, we propose that mutations affecting ANTXR1 function are responsible for this disease’s characteristic generalized defect in extracellular-matrix homeostasis. PMID:23602711

  10. 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.

  11. Pelizaeus-Merzbacher-like Disease Caused by AIMP1/p43 Homozygous Mutation

    PubMed Central

    Feinstein, Miora; Markus, Barak; Noyman, Iris; Shalev, Hannah; Flusser, Hagit; Shelef, Ilan; Liani-Leibson, Keren; Shorer, Zamir; Cohen, Idan; Khateeb, Shareef; Sivan, Sara; Birk, Ohad S.

    2010-01-01

    Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by PLP1 mutations. A similar autosomal-recessive phenotype, Pelizaeus-Merzbacher-like disease (PMLD), has been shown to be caused by homozygous mutations in GJC2 or HSPD1. We report a consanguineous Israeli Bedouin kindred with clinical and radiological findings compatible with PMLD in which linkage to PLP1, GJC2, and HSPD1 was excluded. Through genome-wide homozygosity mapping and mutation analysis, we demonstrated in all affected individuals a homozygous frameshift mutation that fully abrogates the main active domain of AIMP1, encoding ARS-interacting multifunctional protein 1. The mutation fully segregates with the disease-associated phenotype and was not found in 250 Bedouin controls. Our findings are in line with the previously demonstrated inability of mutant mice lacking the AIMP1/p43 ortholog to maintain axon integrity in the central and peripheral neural system. PMID:21092922

  12. ACTN1 mutations cause congenital macrothrombocytopenia.

    PubMed

    Kunishima, Shinji; Okuno, Yusuke; Yoshida, Kenichi; Shiraishi, Yuichi; Sanada, Masashi; Muramatsu, Hideki; Chiba, Kenichi; Tanaka, Hiroko; Miyazaki, Koji; Sakai, Michio; Ohtake, Masatoshi; Kobayashi, Ryoji; Iguchi, Akihiro; Niimi, Gen; Otsu, Makoto; Takahashi, Yoshiyuki; Miyano, Satoru; Saito, Hidehiko; Kojima, Seiji; Ogawa, Seishi

    2013-03-01

    Congenital macrothrombocytopenia (CMTP) is a heterogeneous group of rare platelet disorders characterized by a congenital reduction of platelet counts and abnormally large platelets, for which CMTP-causing mutations are only found in approximately half the cases. We herein performed whole-exome sequencing and targeted Sanger sequencing to identify mutations that cause CMTP, in which a dominant mode of transmission had been suspected but for which no known responsible mutations have been documented. In 13 Japanese CMTP-affected pedigrees, we identified six (46%) affected by ACTN1 variants cosegregating with CMTP. In the entire cohort, ACNT1 variants accounted for 5.5% of the dominant forms of CMTP cases and represented the fourth most common cause in Japanese individuals. Individuals with ACTN1 variants presented with moderate macrothrombocytopenia with anisocytosis but were either asymptomatic or had only a modest bleeding tendency. ACTN1 encodes α-actinin-1, a member of the actin-crosslinking protein superfamily that participates in the organization of the cytoskeleton. In vitro transfection experiments in Chinese hamster ovary cells demonstrated that altered α-actinin-1 disrupted the normal actin-based cytoskeletal structure. Moreover, transduction of mouse fetal liver-derived megakaryocytes with disease-associated ACTN1 variants caused a disorganized actin-based cytoskeleton in megakaryocytes, resulting in the production of abnormally large proplatelet tips, which were reduced in number. Our findings provide an insight into the pathogenesis of CMTP.

  13. WDR19: An ancient, retrograde, intraflagellar ciliary protein is mutated in autosomal recessive retinitis pigmentosa and in Senior-Loken syndrome

    PubMed Central

    Coussa, RG; Otto, EA; Gee, H-Y; Arthurs, P; Ren, H; Lopez, I; Keser, V; Fu, Q; Faingold, R; Khan, A; Schwartzentruber, J; Majewski, J; Hildebrandtand, F; Koenekoop, RK

    2014-01-01

    Autosomal recessive retinitis pigmentosa (arRP) is a clinically and genetically heterogeneous retinal disease that causes blindness. Our purpose was to identify the causal gene, describe the phenotype and delineate the mutation spectrum in a consanguineous Quebec arRP family. We performed Arrayed Primer Extension (APEX) technology to exclude ~500 arRP mutations in ~20 genes. Homozygosity mapping [single nucleotide polymorphism (SNP) genotyping] identified 10 novel significant homozygous regions. We performed next generation sequencing and whole exome capture. Sanger sequencing provided cosegregation. We screened another 150 retinitis pigmentosa (RP) and 200 patients with Senior-Løken Syndrome (SLS). We identified a novel missense mutation in WDR19, c.2129T>C which lead to a p.Leu710Ser. We found the same mutation in a second Quebec arRP family. Interestingly, two of seven affected members of the original family developed ‘sub-clinical’ renal cysts. We hypothesized that more severe WDR19 mutations may lead to severe ciliopathies and found seven WDR19 mutations in five SLS families. We identified a new gene for both arRP and SLS. WDR19 is a ciliary protein associated with the intraflagellar transport machinery. We are currently investigating the full extent of the mutation spectrum. Our findings are crucial in expanding the understanding of childhood blindness and identifying new genes. PMID:23683095

  14. A Missense Mutation in a Highly Conserved Region of CASQ2 Is Associated with Autosomal Recessive Catecholamine-Induced Polymorphic Ventricular Tachycardia in Bedouin Families from Israel

    PubMed Central

    Lahat, Hadas; Pras, Elon; Olender, Tsviya; Avidan, Nili; Ben-Asher, Edna; Man, Orna; Levy-Nissenbaum, Etgar; Khoury, Asad; Lorber, Avraham; Goldman, Boleslaw; Lancet, Doron; Eldar, Michael

    2001-01-01

    Catecholamine-induced polymorphic ventricular tachycardia (PVT) is characterized by episodes of syncope, seizures, or sudden death, in response to physical activity or emotional stress. Two modes of inheritance have been described: autosomal dominant and autosomal recessive. Mutations in the ryanodine receptor 2 gene (RYR2), which encodes a cardiac sarcoplasmic reticulum (SR) Ca2+-release channel, were recently shown to cause the autosomal dominant form of the disease. In the present report, we describe a missense mutation in a highly conserved region of the calsequestrin 2 gene (CASQ2) as the potential cause of the autosomal recessive form. The CASQ2 protein serves as the major Ca2+ reservoir within the SR of cardiac myocytes and is part of a protein complex that contains the ryanodine receptor. The mutation, which is in full segregation in seven Bedouin families affected by the disorder, converts a negatively charged aspartic acid into a positively charged histidine, in a highly negatively charged domain, and is likely to exert its deleterious effect by disrupting Ca2+ binding. PMID:11704930

  15. Recessive congenital methemoglobinemia caused by a rare mechanism: maternal uniparental heterodisomy with segmental isodisomy of a chromosome 22.

    PubMed

    Huang, Yu-Hsiu; Tai, Chang-Long; Lu, Yung-Hsiu; Wu, Tina Jui-Ting; Chen, Hong-Duo; Niu, Dau-Ming

    2012-08-15

    Recessive congenital methemoglobinemia (RCM) is a very rare disorder caused by NADH-cytochrome b5 reductase (cb5r) deficiency. Two distinct clinical forms, types I and II, caused by cb5r deficiency have been recognized. In type I, the enzyme deficiency is restricted only to erythrocytes with cyanosis being the only major symptom. In contrast, in type II, the enzyme deficiency is generalized to all tissues and associated with neurological impairment, mental and growth retardation and reduced life expectancy, in addition to cyanosis. Recently, we conducted a study on an 11-year-old boy with cb5r deficiency type I. The mutational analysis of the CYB5R3 gene revealed that the boy is homozygous for L72P mutation. Surprisingly, his mother is heterozygous for this L72P mutant, but not his father. Thirteen microsatellite markers of chromosome 22 were selected to analyze the origins of the patient's chromosome 22. The result showed that both of the chromosome 22(s) of this patient came from the maternal side (uniparental heterodisomy of chromosome 22 with segmental isodisomy). This is the first case report of a patient with cb5r deficiency type I resulting from uniparental disomy and also discloses an alternate mechanism whereby this enzymatic disorder can be derived from a single parent. PMID:22658170

  16. NGS-Based Assay for the Identification of Individuals Carrying Recessive Genetic Mutations in Reproductive Medicine.

    PubMed

    Abulí, Anna; Boada, Montserrat; Rodríguez-Santiago, Benjamín; Coroleu, Buenaventura; Veiga, Anna; Armengol, Lluís; Barri, Pedro N; Pérez-Jurado, Luis A; Estivill, Xavier

    2016-06-01

    Next-generation sequencing (NGS) has the capacity of carrier screening in gamete donation (GD) programs. We have developed and validated an NGS carrier-screening test (qCarrier test) that includes 200 genes associated with 368 disorders (277 autosomal recessive and 37 X-linked). Carrier screening is performed on oocyte donation candidates and the male partner of oocyte recipient. Carriers of X-linked conditions are excluded from the GD program, whereas donors are chosen who do not carry mutations for the same gene/disease as the recipients. The validation phase showed a high sensitivity (>99% sensitivity) detecting all single-nucleotide variants, 13 indels, and 25 copy-number variants included in the validation set. A total of 1,301 individuals were analysed with the qCarrier test, including 483 candidate oocyte donors and 635 receptor couples, 105 females receiving sperm donation, and 39 couples seeking pregnancy. We identified 56% of individuals who are carriers for at least one genetic condition and 1.7% of female donors who were excluded from the program due to a carrier state of X-linked conditions. Globally, 3% of a priori assigned donations had a high reproductive risk that could be minimized after testing. Genetic counselling at different stages is essential for helping to facilitate a successful and healthy pregnancy.

  17. NGS-Based Assay for the Identification of Individuals Carrying Recessive Genetic Mutations in Reproductive Medicine.

    PubMed

    Abulí, Anna; Boada, Montserrat; Rodríguez-Santiago, Benjamín; Coroleu, Buenaventura; Veiga, Anna; Armengol, Lluís; Barri, Pedro N; Pérez-Jurado, Luis A; Estivill, Xavier

    2016-06-01

    Next-generation sequencing (NGS) has the capacity of carrier screening in gamete donation (GD) programs. We have developed and validated an NGS carrier-screening test (qCarrier test) that includes 200 genes associated with 368 disorders (277 autosomal recessive and 37 X-linked). Carrier screening is performed on oocyte donation candidates and the male partner of oocyte recipient. Carriers of X-linked conditions are excluded from the GD program, whereas donors are chosen who do not carry mutations for the same gene/disease as the recipients. The validation phase showed a high sensitivity (>99% sensitivity) detecting all single-nucleotide variants, 13 indels, and 25 copy-number variants included in the validation set. A total of 1,301 individuals were analysed with the qCarrier test, including 483 candidate oocyte donors and 635 receptor couples, 105 females receiving sperm donation, and 39 couples seeking pregnancy. We identified 56% of individuals who are carriers for at least one genetic condition and 1.7% of female donors who were excluded from the program due to a carrier state of X-linked conditions. Globally, 3% of a priori assigned donations had a high reproductive risk that could be minimized after testing. Genetic counselling at different stages is essential for helping to facilitate a successful and healthy pregnancy. PMID:26990548

  18. Two novel mutations on exon 8 and intron 65 of COL7A1 gene in two Chinese brothers result in recessive dystrophic epidermolysis bullosa.

    PubMed

    Lin, Ying; Chen, Xue-Jun; Liu, Wei; Gong, Bo; Xie, Jun; Xiong, Jun-Hao; Cheng, Jing; Duan, Xi-Ling; Lin, Zhao-Chun; Huang, Lu-Lin; Wan, Hui-Ying; Liu, Xiao-Qi; Song, Lin-Hong; Yang, Zheng-Lin

    2012-01-01

    Dystrophic epidermolysis bullosa is an inherited bullous dermatosis caused by the COL7A1 gene mutation in autosomal dominant or recessive mode. COL7A1 gene encodes type VII collagen - the main component of the anchoring fibrils at the dermal-epidermal junction. Besides the 730 mutations reported, we identified two novel COL7A1 gene mutations in a Chinese family, which caused recessive dystrophic epidermolysis bullosa (RDEB). The diagnosis was established histopathologically and ultrastructurally. After genomic DNA extraction from the peripheral blood sample of all subjects (5 pedigree members and 136 unrelated control individuals), COL7A1 gene screening was performed by polymerase chain reaction amplification and direct DNA sequencing of the whole coding exons and flanking intronic regions. Genetic analysis of the COL7A1 gene in affected individuals revealed compound heterozygotes with identical novel mutations. The maternal mutation is a 2-bp deletion at exon 8 (c.1006_1007delCA), leading to a subsequent reading frame-shift and producing a premature termination codon located 48 amino acids downstream in exon 9 (p.Q336EfsX48), consequently resulting in the truncation of 2561 amino acids downstream. This was only present in two affected brothers, but not in the other unaffected family members. The paternal mutation is a 1-bp deletion occurring at the first base of intron 65 (c.IVS5568+1delG) that deductively changes the strongly conserved GT dinucleotide at the 5' donor splice site, results in subsequent reading-through into intron 65, and creates a stop codon immediately following the amino acids encoded by exon 65 (GTAA→TAA). This is predicted to produce a truncated protein lacking of 1089 C-terminal amino acids downstream. The latter mutation was found in all family members except one of the two unaffected sisters. Both mutations were observed concurrently only in the two affected brothers. Neither mutation was discovered in 136 unrelated Chinese control

  19. Autosomal-Dominant Multiple Pterygium Syndrome Is Caused by Mutations in MYH3

    PubMed Central

    Chong, Jessica X.; Burrage, Lindsay C.; Beck, Anita E.; Marvin, Colby T.; McMillin, Margaret J.; Shively, Kathryn M.; Harrell, Tanya M.; Buckingham, Kati J.; Bacino, Carlos A.; Jain, Mahim; Alanay, Yasemin; Berry, Susan A.; Carey, John C.; Gibbs, Richard A.; Lee, Brendan H.; Krakow, Deborah; Shendure, Jay; Nickerson, Deborah A.; Bamshad, Michael J.; Shendure, Jay; Nickerson, Deborah A.; Abecasis, Gonçalo R.; Anderson, Peter; Blue, Elizabeth Marchani; Annable, Marcus; Browning, Brian L.; Buckingham, Kati J.; Chen, Christina; Chin, Jennifer; Chong, Jessica X.; Cooper, Gregory M.; Davis, Colleen P.; Frazar, Christopher; Harrell, Tanya M.; He, Zongxiao; Jain, Preti; Jarvik, Gail P.; Jimenez, Guillaume; Johanson, Eric; Jun, Goo; Kircher, Martin; Kolar, Tom; Krauter, Stephanie A.; Krumm, Niklas; Leal, Suzanne M.; Luksic, Daniel; Marvin, Colby T.; McMillin, Margaret J.; McGee, Sean; O’Reilly, Patrick; Paeper, Bryan; Patterson, Karynne; Perez, Marcos; Phillips, Sam W.; Pijoan, Jessica; Poel, Christa; Reinier, Frederic; Robertson, Peggy D.; Santos-Cortez, Regie; Shaffer, Tristan; Shephard, Cindy; Shively, Kathryn M.; Siegel, Deborah L.; Smith, Joshua D.; Staples, Jeffrey C.; Tabor, Holly K.; Tackett, Monica; Underwood, Jason G.; Wegener, Marc; Wang, Gao; Wheeler, Marsha M.; Yi, Qian; Bamshad, Michael J.

    2015-01-01

    Multiple pterygium syndrome (MPS) is a phenotypically and genetically heterogeneous group of rare Mendelian conditions characterized by multiple pterygia, scoliosis, and congenital contractures of the limbs. MPS typically segregates as an autosomal-recessive disorder, but rare instances of autosomal-dominant transmission have been reported. Whereas several mutations causing recessive MPS have been identified, the genetic basis of dominant MPS remains unknown. We identified four families affected by dominantly transmitted MPS characterized by pterygia, camptodactyly of the hands, vertebral fusions, and scoliosis. Exome sequencing identified predicted protein-altering mutations in embryonic myosin heavy chain (MYH3) in three families. MYH3 mutations underlie distal arthrogryposis types 1, 2A, and 2B, but all mutations reported to date occur in the head and neck domains. In contrast, two of the mutations found to cause MPS in this study occurred in the tail domain. The phenotypic overlap among persons with MPS, coupled with physical findings distinct from other conditions caused by mutations in MYH3, suggests that the developmental mechanism underlying MPS differs from that of other conditions and/or that certain functions of embryonic myosin might be perturbed by disruption of specific residues and/or domains. Moreover, the vertebral fusions in persons with MPS, coupled with evidence of MYH3 expression in bone, suggest that embryonic myosin plays a role in skeletal development. PMID:25957469

  20. Autosomal-Dominant Multiple Pterygium Syndrome Is Caused by Mutations in MYH3.

    PubMed

    Chong, Jessica X; Burrage, Lindsay C; Beck, Anita E; Marvin, Colby T; McMillin, Margaret J; Shively, Kathryn M; Harrell, Tanya M; Buckingham, Kati J; Bacino, Carlos A; Jain, Mahim; Alanay, Yasemin; Berry, Susan A; Carey, John C; Gibbs, Richard A; Lee, Brendan H; Krakow, Deborah; Shendure, Jay; Nickerson, Deborah A; Bamshad, Michael J

    2015-05-01

    Multiple pterygium syndrome (MPS) is a phenotypically and genetically heterogeneous group of rare Mendelian conditions characterized by multiple pterygia, scoliosis, and congenital contractures of the limbs. MPS typically segregates as an autosomal-recessive disorder, but rare instances of autosomal-dominant transmission have been reported. Whereas several mutations causing recessive MPS have been identified, the genetic basis of dominant MPS remains unknown. We identified four families affected by dominantly transmitted MPS characterized by pterygia, camptodactyly of the hands, vertebral fusions, and scoliosis. Exome sequencing identified predicted protein-altering mutations in embryonic myosin heavy chain (MYH3) in three families. MYH3 mutations underlie distal arthrogryposis types 1, 2A, and 2B, but all mutations reported to date occur in the head and neck domains. In contrast, two of the mutations found to cause MPS in this study occurred in the tail domain. The phenotypic overlap among persons with MPS, coupled with physical findings distinct from other conditions caused by mutations in MYH3, suggests that the developmental mechanism underlying MPS differs from that of other conditions and/or that certain functions of embryonic myosin might be perturbed by disruption of specific residues and/or domains. Moreover, the vertebral fusions in persons with MPS, coupled with evidence of MYH3 expression in bone, suggest that embryonic myosin plays a role in skeletal development.

  1. Loss of VPS13C Function in Autosomal-Recessive Parkinsonism Causes Mitochondrial Dysfunction and Increases PINK1/Parkin-Dependent Mitophagy.

    PubMed

    Lesage, Suzanne; Drouet, Valérie; Majounie, Elisa; Deramecourt, Vincent; Jacoupy, Maxime; Nicolas, Aude; Cormier-Dequaire, Florence; Hassoun, Sidi Mohamed; Pujol, Claire; Ciura, Sorana; Erpapazoglou, Zoi; Usenko, Tatiana; Maurage, Claude-Alain; Sahbatou, Mourad; Liebau, Stefan; Ding, Jinhui; Bilgic, Basar; Emre, Murat; Erginel-Unaltuna, Nihan; Guven, Gamze; Tison, François; Tranchant, Christine; Vidailhet, Marie; Corvol, Jean-Christophe; Krack, Paul; Leutenegger, Anne-Louise; Nalls, Michael A; Hernandez, Dena G; Heutink, Peter; Gibbs, J Raphael; Hardy, John; Wood, Nicholas W; Gasser, Thomas; Durr, Alexandra; Deleuze, Jean-François; Tazir, Meriem; Destée, Alain; Lohmann, Ebba; Kabashi, Edor; Singleton, Andrew; Corti, Olga; Brice, Alexis

    2016-03-01

    Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression. PMID:26942284

  2. Loss of VPS13C Function in Autosomal-Recessive Parkinsonism Causes Mitochondrial Dysfunction and Increases PINK1/Parkin-Dependent Mitophagy

    PubMed Central

    Lesage, Suzanne; Drouet, Valérie; Majounie, Elisa; Deramecourt, Vincent; Jacoupy, Maxime; Nicolas, Aude; Cormier-Dequaire, Florence; Hassoun, Sidi Mohamed; Pujol, Claire; Ciura, Sorana; Erpapazoglou, Zoi; Usenko, Tatiana; Maurage, Claude-Alain; Sahbatou, Mourad; Liebau, Stefan; Ding, Jinhui; Bilgic, Basar; Emre, Murat; Erginel-Unaltuna, Nihan; Guven, Gamze; Tison, François; Tranchant, Christine; Vidailhet, Marie; Corvol, Jean-Christophe; Krack, Paul; Leutenegger, Anne-Louise; Nalls, Michael A.; Hernandez, Dena G.; Heutink, Peter; Gibbs, J. Raphael; Hardy, John; Wood, Nicholas W.; Gasser, Thomas; Durr, Alexandra; Deleuze, Jean-François; Tazir, Meriem; Destée, Alain; Lohmann, Ebba; Kabashi, Edor; Singleton, Andrew; Corti, Olga; Brice, Alexis; Lesage, Suzanne; Tison, François; Vidailhet, Marie; Corvol, Jean-Christophe; Agid, Yves; Anheim, Mathieu; Bonnet, Anne-Marie; Borg, Michel; Broussolle, Emmanuel; Damier, Philippe; Destée, Alain; Dürr, Alexandra; Durif, Franck; Krack, Paul; Klebe, Stephan; Lohmann, Ebba; Martinez, Maria; Pollak, Pierre; Rascol, Olivier; Tranchant, Christine; Vérin, Marc; Viallet, François; Brice, Alexis; Lesage, Suzanne; Majounie, Elisa; Tison, François; Vidailhet, Marie; Corvol, Jean Christophe; Nalls, Michael A.; Hernandez, Dena G.; Gibbs, J. Raphael; Dürr, Alexandra; Arepalli, Sampath; Barker, Roger A.; Ben-Shlomo, Yoav; Berg, Daniela; Bettella, Francesco; Bhatia, Kailash; de Bie, Rob M.A.; Biffi, Alessandro; Bloem, Bastiaan R.; Bochdanovits, Zoltan; Bonin, Michael; Lesage, Suzanne; Tison, François; Vidailhet, Marie; Corvol, Jean-Christophe; Agid, Yves; Anheim, Mathieu; Bonnet, Anne-Marie; Borg, Michel; Broussolle, Emmanuel; Damier, Philippe; Destée, Alain; Dürr, Alexandra; Durif, Franck; Krack, Paul; Klebe, Stephan; Lohmann, Ebba; Martinez, Maria; Pollak, Pierre; Rascol, Olivier; Tranchant, Christine; Vérin, Marc; Bras, Jose M.; Brockmann, Kathrin; Brooks, Janet; Burn, David J.; Charlesworth, Gavin; Chen, Honglei; Chinnery, Patrick F.; Chong, Sean; Clarke, Carl E.; Cookson, Mark R.; Counsell, Carl; Damier, Philippe; Dartigues, Jean-François; Deloukas, Panos; Deuschl, Günther; Dexter, David T.; van Dijk, Karin D.; Dillman, Allissa; Dong, Jing; Durif, Frank; Edkins, Sarah; Escott-Price, Valentina; Evans, Jonathan R.; Foltynie, Thomas; Gao, Jianjun; Gardner, Michelle; Goate, Alison; Gray, Emma; Guerreiro, Rita; Harris, Clare; van Hilten, Jacobus J.; Hofman, Albert; Hollenbeck, Albert; Holmans, Peter; Holton, Janice; Hu, Michèle; Huang, Xuemei; Huber, Heiko; Hudson, Gavin; Hunt, Sarah E.; Huttenlocher, Johanna; Illig, Thomas; Jónsson, Pálmi V.; Kilarski, Laura L.; Jansen, Iris E.; Lambert, Jean-Charles; Langford, Cordelia; Lees, Andrew; Lichtner, Peter; Limousin, Patricia; Lopez, Grisel; Lorenz, Delia; Lubbe, Steven; Lungu, Codrin; Martinez, María; Mätzler, Walter; McNeill, Alisdair; Moorby, Catriona; Moore, Matthew; Morrison, Karen E.; Mudanohwo, Ese; O’Sullivan, Sean S.; Owen, Michael J.; Pearson, Justin; Perlmutter, Joel S.; Pétursson, Hjörvar; Plagnol, Vincent; Pollak, Pierre; Post, Bart; Potter, Simon; Ravina, Bernard; Revesz, Tamas; Riess, Olaf; Rivadeneira, Fernando; Rizzu, Patrizia; Ryten, Mina; Saad, Mohamad; Simón-Sánchez, Javier; Sawcer, Stephen; Schapira, Anthony; Scheffer, Hans; Schulte, Claudia; Sharma, Manu; Shaw, Karen; Sheerin, Una-Marie; Shoulson, Ira; Shulman, Joshua; Sidransky, Ellen; Spencer, Chris C.A.; Stefánsson, Hreinn; Stefánsson, Kári; Stockton, Joanna D.; Strange, Amy; Talbot, Kevin; Tanner, Carlie M.; Tashakkori-Ghanbaria, Avazeh; Trabzuni, Daniah; Traynor, Bryan J.; Uitterlinden, André G.; Velseboer, Daan; Walker, Robert; van de Warrenburg, Bart; Wickremaratchi, Mirdhu; Williams-Gray, Caroline H.; Winder-Rhodes, Sophie; Wurster, Isabel; Williams, Nigel; Morris, Huw R.; Heutink, Peter; Hardy, John; Wood, Nicholas W.; Gasser, Thomas; Singleton, Andrew B.; Brice, Alexis

    2016-01-01

    Autosomal-recessive early-onset parkinsonism is clinically and genetically heterogeneous. The genetic causes of approximately 50% of autosomal-recessive early-onset forms of Parkinson disease (PD) remain to be elucidated. Homozygozity mapping and exome sequencing in 62 isolated individuals with early-onset parkinsonism and confirmed consanguinity followed by data mining in the exomes of 1,348 PD-affected individuals identified, in three isolated subjects, homozygous or compound heterozygous truncating mutations in vacuolar protein sorting 13C (VPS13C). VPS13C mutations are associated with a distinct form of early-onset parkinsonism characterized by rapid and severe disease progression and early cognitive decline; the pathological features were striking and reminiscent of diffuse Lewy body disease. In cell models, VPS13C partly localized to the outer membrane of mitochondria. Silencing of VPS13C was associated with lower mitochondrial membrane potential, mitochondrial fragmentation, increased respiration rates, exacerbated PINK1/Parkin-dependent mitophagy, and transcriptional upregulation of PARK2 in response to mitochondrial damage. This work suggests that loss of function of VPS13C is a cause of autosomal-recessive early-onset parkinsonism with a distinctive phenotype of rapid and severe progression. PMID:26942284

  3. ABCA12 mutations and autosomal recessive congenital ichthyosis: a review of genotype/phenotype correlations and of pathogenetic concepts.

    PubMed

    Akiyama, Masashi

    2010-10-01

    Mutations in ABCA12 have been described in autosomal recessive congenital ichthyoses (ARCI) including harlequin ichthyosis (HI), congenital ichthyosiform erythroderma (CIE), and lamellar ichthyosis (LI). HI shows the most severe phenotype. CIE and LI are clinically characterized by fine, whitish scales on a background of erythematous skin, and large, thick, dark scales over the entire body without serious background erythroderma, respectively. To date, a total of 56 ABCA12 mutations have been reported in 66 ARCI families including 48 HI, 10 LI, and 8 CIE families of African, European, Pakistani/Indian, and Japanese origin (online database: http://www.derm-hokudai.jp/ABCA12/). A total of 62.5% of reported ABCA12 mutations are expected to lead to truncated proteins. Most mutations in HI are truncation mutations and homozygous or compound heterozygous truncation mutations always results in HI phenotype. In CIE families, at least one mutation on each allele is typically a missense mutation. Combinations of missense mutations in the first ATP-binding cassette of ABCA12 underlie the LI phenotype. ABCA12 is a keratinocyte lipid transporter associated with lipid transport in lamellar granules, and loss of ABCA12 function leads to a defective lipid barrier in the stratum corneum, resulting in an ichthyotic phenotype. Recent work using mouse models confirmed ABCA12 roles in skin barrier formation.

  4. Dominant and Recessive Forms of Fibrochondrogenesis Resulting from Mutations at a Second Locus, COL11A2

    PubMed Central

    Tompson, Stuart W.; Faqeih, Eissa Ali; Ala-Kokko, Leena; Hecht, Jacqueline T.; Miki, Rika; Funari, Tara; Funari, Vincent A.; Nevarez, Lisette; Krakow, Deborah; Cohn, Daniel H.

    2011-01-01

    Fibrochondrogenesis is a severe, recessively inherited skeletal dysplasia shown to result from mutations in the gene encoding the proα1(XI) chain of type XI collagen, COL11A1. The first of two cases reported here was the affected offspring of first cousins and sequence analysis excluded mutations in COL11A1. Consequently, whole-genome SNP genotyping was performed to identify blocks of homozygosity, identical-by-descent, wherein the disease locus would reside. COL11A1 was not within a region of homozygosity, further excluding it as the disease locus, but the gene encoding the proα2(XI) chain of type XI collagen, COL11A2, was located within a large region of homozygosity. Sequence analysis identified homozygosity for a splice donor mutation in intron 18. Exon trapping demonstrated that the mutation resulted in skipping of exon 18 and predicted deletion of 18 amino acids from the triple helical domain of the protein. In the second case, heterozygosity for a de novo 9 bp deletion in exon 40 of COL11A2 was identified, indicating that there are autosomal dominant forms of fibrochondrogenesis. These findings thus demonstrate that fibrochondrogenesis can result from either recessively- or dominantly-inherited mutations in COL11A2. PMID:22246659

  5. Mutations in XRCC4 cause primordial dwarfism without causing immunodeficiency.

    PubMed

    Saito, Shinta; Kurosawa, Aya; Adachi, Noritaka

    2016-08-01

    In successive reports from 2014 to 2015, X-ray repair cross-complementing protein 4 (XRCC4) has been identified as a novel causative gene of primordial dwarfism. XRCC4 is indispensable for non-homologous end joining (NHEJ), the major pathway for repairing DNA double-strand breaks. As NHEJ is essential for V(D)J recombination during lymphocyte development, it is generally believed that abnormalities in XRCC4 cause severe combined immunodeficiency. Contrary to expectations, however, no overt immunodeficiency has been observed in patients with primordial dwarfism harboring XRCC4 mutations. Here, we describe the various XRCC4 mutations that lead to disease and discuss their impact on NHEJ and V(D)J recombination. PMID:27169690

  6. Mutations in XRCC4 cause primordial dwarfism without causing immunodeficiency.

    PubMed

    Saito, Shinta; Kurosawa, Aya; Adachi, Noritaka

    2016-08-01

    In successive reports from 2014 to 2015, X-ray repair cross-complementing protein 4 (XRCC4) has been identified as a novel causative gene of primordial dwarfism. XRCC4 is indispensable for non-homologous end joining (NHEJ), the major pathway for repairing DNA double-strand breaks. As NHEJ is essential for V(D)J recombination during lymphocyte development, it is generally believed that abnormalities in XRCC4 cause severe combined immunodeficiency. Contrary to expectations, however, no overt immunodeficiency has been observed in patients with primordial dwarfism harboring XRCC4 mutations. Here, we describe the various XRCC4 mutations that lead to disease and discuss their impact on NHEJ and V(D)J recombination.

  7. Nemaline myopathy caused byTNNT1 mutations in a Dutch pedigree.

    PubMed

    van der Pol, W Ludo; Leijenaar, Jolien F; Spliet, Wim G M; Lavrijsen, Selma W; Jansen, Nicolaas J G; Braun, Kees P J; Mulder, Marcel; Timmers-Raaijmakers, Brigitte; Ratsma, Kimberly; Dooijes, Dennis; van Haelst, Mieke M

    2014-03-01

    Nemaline myopathy (NM) is genetically heterogeneous disorder characterized by early onset muscular weakness and sarcoplasmatic or intranuclear inclusions of rod-shaped Z-disk material in muscle fibers. Thus far, mutations in seven genes have been identified as cause of NM. Only one singleTNNT1 nonsense mutation has been previously described that causes autosomal recessive NM in the old order Amish with a very specific clinical phenotype including rapidly progressive contractures. Here, we report a patient who is compound heterozygous for a c.309+1G>A mutation and an exon 14 deletion in theTNNT1 gene. This report confirms the specific clinical phenotype ofTNNT1 NM and documents two newTNNT1 mutations outside the old order Amish. PMID:24689076

  8. Autosomal recessive

    MedlinePlus

    ... and the other gene comes from the father. Recessive inheritance means both genes in a pair must be abnormal to cause ... born to parents who carry the same autosomal recessive change ... abnormal gene from both parents and developing the disease. You ...

  9. RYR1 mutations cause ophthalmoplegia, facial weakness, and malignant hyperthermia

    PubMed Central

    Shaaban, Sherin; Ramos-Platt, Leigh; Gilles, Floyd H.; Chan, Wai-Man; Andrews, Caroline; De Girolami, Umberto; Demer, Joseph; Engle, Elizabeth C

    2013-01-01

    Objective To determine the genetic cause of congenital ptosis, ophthalmoplegia, facial paralysis and mild hypotonia segregating in two pedigrees diagnosed with atypical Moebius syndrome or congenital fibrosis of the extraocular muscles (CFEOM). Methods Homozygosity mapping and whole-exome sequencing were conducted to identify causative mutations in affected family members. Histories, physical examinations, and clinical data were reviewed. Results Missense mutations resulting in two homozygous RYR1 amino acid substitutions (E989G and R3772W) and two compound heterozygous RYR1 substitutions (H283R and R3772W) were identified in a consanguineous and a non-consanguineous pedigree, respectively. Orbital magnetic resonance imaging (MRI) revealed marked hypoplasia of extraocular muscles and intraorbital cranial nerves. Skeletal muscle biopsies revealed non-specific myopathic changes. Clinically, the patients’ ophthalmoplegia and facial weakness were far more significant than their hypotonia and limb weakness, and were accompanied by an unrecognized susceptibility to malignant hyperthermia. Conclusions Affected children presenting with severe congenital ophthalmoplegia and facial weakness in the setting of only mild skeletal myopathy harbored recessive mutations in RYR1, encoding the ryanodine receptor 1, and were susceptible to malignant hyperthermia. While ophthalmoplegia occurs rarely in RYR1-related myopathies, these children were atypical because they lacked significant weakness, respiratory insufficiency, or scoliosis. Clinical relevance RYR1-associated myopathies should be included in the differential diagnosis of congenital ophthalmoplegia and facial weakness, even without clinical skeletal myopathy. These patients should also be considered susceptible to malignant hyperthermia, a life-threatening anesthetic complication avoidable if anticipated pre-surgically. PMID:24091937

  10. NK cells are intrinsically functional in pigs with Severe Combined Immunodeficiency (SCID) caused by spontaneous mutations in the Artemis gene

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We have identified Severe Combined Immunodeficiency (SCID) in a line of Yorkshire pigs at Iowa State University. These SCID pigs lack B-cells and T-cells, but possess Natural Killer (NK) cells. This SCID phenotype is caused by recessive mutations in the Artemis gene. Interestingly, two human tumor c...

  11. Novel TK2 mutations as a cause of delayed muscle maturation in mtDNA depletion syndrome.

    PubMed

    Termglinchan, Thanes; Hisamatsu, Seito; Ohmori, Junko; Suzumura, Hiroshi; Sumitomo, Noriko; Imataka, George; Arisaka, Osamu; Murakami, Nobuyuki; Minami, Narihiro; Akihiko, Ishiyama; Sasaki, Masayuki; Goto, Yuichi; Noguchi, Satoru; Nonaka, Ikuya; Mitsuhashi, Satomi; Nishino, Ichizo

    2016-10-01

    Recessive mutations in TK2 cause a severe mitochondrial DNA depletion syndrome (MDS),(1) characterized by severe myopathy from early infancy. Recent reports have suggested a wider clinical spectrum including encephalomyopathic form.(1,2) We report a patient with infantile-onset fatal encephalomyopathy presenting with extreme muscle fiber immaturity. PMID:27660820

  12. Novel TK2 mutations as a cause of delayed muscle maturation in mtDNA depletion syndrome.

    PubMed

    Termglinchan, Thanes; Hisamatsu, Seito; Ohmori, Junko; Suzumura, Hiroshi; Sumitomo, Noriko; Imataka, George; Arisaka, Osamu; Murakami, Nobuyuki; Minami, Narihiro; Akihiko, Ishiyama; Sasaki, Masayuki; Goto, Yuichi; Noguchi, Satoru; Nonaka, Ikuya; Mitsuhashi, Satomi; Nishino, Ichizo

    2016-10-01

    Recessive mutations in TK2 cause a severe mitochondrial DNA depletion syndrome (MDS),(1) characterized by severe myopathy from early infancy. Recent reports have suggested a wider clinical spectrum including encephalomyopathic form.(1,2) We report a patient with infantile-onset fatal encephalomyopathy presenting with extreme muscle fiber immaturity.

  13. Late-onset Charcot-Marie-Tooth disease 4F caused by periaxin gene mutation.

    PubMed

    Tokunaga, Shoko; Hashiguchi, Akihiro; Yoshimura, Akiko; Maeda, Kengo; Suzuki, Takashi; Haruki, Hiroyo; Nakamura, Tomonori; Okamoto, Yuji; Takashima, Hiroshi

    2012-11-01

    We identified the main features of Charcot-Marie-Tooth (CMT) disease, type 4F, caused by a periaxin gene (PRX) mutation in Japanese patients. Periaxin is known as one of the key myelination molecules, forming tight junction between myelin loop and axon. We collected 427 DNA samples from individuals with CMT or CMT-related neuropathy, negative for PMP22 duplication. We investigated PRX mutations using a purpose-built resequencing array screen during the period 2006-2012. We detected two types of PRX mutations in three patients; one patient showed a novel homozygous p.D651N mutation and the other two showed homozygous p.R1070X mutation. All PRX mutations reported so far have been of nonsense or frameshift type. In this study, we found homozygous missense mutation p.D651N. Aspartate 651 is located in a repeat domain; its position might indicate an important function. PRX mutations usually lead to early-onset, autosomal-recessive demyelinating CMT neuropathy 4F (CMT4F) or Dejerine-Sottas disease; their clinical phenotypes are severe. In our three patients, the onset of the disease was at the age of 27 years or later, and their clinical phenotypes were milder compared with those reported in previous studies. We showed a variation of clinical phenotypes for CMT4F caused by a novel, nonsense PRX mutation. PMID:22847150

  14. Homozygous missense and nonsense mutations in BMPR1B cause acromesomelic chondrodysplasia-type Grebe.

    PubMed

    Graul-Neumann, Luitgard M; Deichsel, Alexandra; Wille, Ulrike; Kakar, Naseebullah; Koll, Randi; Bassir, Christian; Ahmad, Jamil; Cormier-Daire, Valerie; Mundlos, Stefan; Kubisch, Christian; Borck, Guntram; Klopocki, Eva; Mueller, Thomas D; Doelken, Sandra C; Seemann, Petra

    2014-06-01

    Acromesomelic chondrodysplasias (ACDs) are characterized by disproportionate shortening of the appendicular skeleton, predominantly affecting the middle (forearms and forelegs) and distal segments (hands and feet). Here, we present two consanguineous families with missense (c.157T>C, p.(C53R)) or nonsense (c.657G>A, p.(W219*)) mutations in BMPR1B. Homozygous affected individuals show clinical and radiographic findings consistent with ACD-type Grebe. Functional analysis of the missense mutation C53R revealed that the mutated receptor was partially located at the cell membrane. In contrast to the wild-type receptor, C53R mutation hindered the activation of the receptor by its ligand GDF5, as shown by reporter gene assay. Further, overexpression of the C53R mutation in an in vitro chondrogenesis assay showed no effect on cell differentiation, indicating a loss of function. The nonsense mutation (c.657G>A, p.(W219*)) introduces a premature stop codon, which is predicted to be subject to nonsense-mediated mRNA decay, causing reduced protein translation of the mutant allele. A loss-of-function effect of both mutations causing recessive ACD-type Grebe is further supported by the mild brachydactyly or even non-penetrance of these mutations observed in the heterozygous parents. In contrast, dominant-negative BMPR1B mutations described previously are associated with autosomal-dominant brachydactyly-type A2. PMID:24129431

  15. Mutations in GJA1 (connexin 43) are associated with non-syndromic autosomal recessive deafness.

    PubMed

    Liu, X Z; Xia, X J; Adams, J; Chen, Z Y; Welch, K O; Tekin, M; Ouyang, X M; Kristiansen, A; Pandya, A; Balkany, T; Arnos, K S; Nance, W E

    2001-12-01

    Mutations in four members of the connexin gene family have been shown to underlie distinct genetic forms of deafness, including GJB2 [connexin 26 (Cx26)], GJB3 (Cx31), GJB6 (Cx30) and GJB1 (Cx32). We have found that alterations in a fifth member of this family, GJA1 (Cx43), appear to cause a common form of deafness in African Americans. We identified two different GJA1 mutations in four of 26 African American probands. Three were homozygous for a Leu-->Phe substitution in the absolutely conserved codon 11, whereas the other was homozygous for a Val-->Ala transversion at the highly conserved codon 24. Neither mutation was detected in DNA from 100 control subjects without deafness. Cx43 is expressed in the cochlea, as is demonstrated by PCR amplification from human fetal cochlear cDNA and by RT-PCR of mouse cochlear tissues. Immunohistochemical staining of mouse cochlear preparations showed immunostaining for Cx43 in non-sensory epithelial cells and in fibrocytes of the spiral ligament and the spiral limbus. To our knowledge this is the first alpha connexin gene to be associated with non-syndromic deafness. Cx43 must also play a critical role in the physiology of hearing, presumably by participating in the recycling of potassium to the cochlear endolymph. PMID:11741837

  16. A novel recessive 15-hydroxyprostaglandin dehydrogenase mutation in a family with primary hypertrophic osteoarthropathy.

    PubMed

    Erken, Eren; Köroğlu, Çiğdem; Yıldız, Fatih; Özer, Hüseyin T E; Gülek, Bozkurt; Tolun, Aslıhan

    2015-03-01

    We present two PHO siblings having a novel homozygous truncating mutation in HPGD. The purpose of the study was to attempt medical treatment, and to find the HPGD mutation causing the disease, in a 22-year old Turkish male and his 23-year old sister afflicted with primary hypertrophic osteoarthropathy (PHO). In combination with NSAIDs and colchicine, treatment with sulfasalazine was started in both cases, and methotrexate was added to the treatment regimen of the female patient at the end of the first year. The patients were found to be typical PHO. Ultrasonographic examination of the joints revealed synovitis and inflammation by B mode and power Doppler ultrasonography. Joint symptoms responded to sulfasalazine treatment in both patients. However, after the addition of methotrexate, the female patient had better remission. All exons of HPGD, the known disease gene, were analyzed by Sanger sequencing. A homozygous 2-bp deletion (c.310_311delCT or p.L104AfsX3) was identified. Seven relatives carrying the mutation in the heterozygous state were examined and none was found affected. Although not specific for this disease, skin, soft tissue and joint ultrasonography can be helpful for evaluation of the musculoskeletal findings in the patients. PMID:24533558

  17. Mutations in the ganglioside-induced differentiation-associated protein-1 (GDAP1) gene in intermediate type autosomal recessive Charcot-Marie-Tooth neuropathy.

    PubMed

    Senderek, Jan; Bergmann, Carsten; Ramaekers, Vincent T; Nelis, Eva; Bernert, Günther; Makowski, Astrid; Züchner, Stephan; De Jonghe, Peter; Rudnik-Schöneborn, Sabine; Zerres, Klaus; Schröder, J Michael

    2003-03-01

    Mutations in the gene for the ganglioside-induced differentiation-associated protein-1 (GDAP1) on 8q21 recently were reported to cause autosomal recessive Charcot-Marie-Tooth (CMT) sensorimotor neuropathy. Neurophysiology and nerve pathology were heterogeneous in these cases: a subset of GDAP1 mutations was associated with peripheral nerve demyelination, whereas others resulted in axonal degeneration. In this study, we identified two novel mutations disrupting the GDAP1 reading frame. Homozygosity for a single base pair insertion in exon 3 (c.349_350insT) was observed in affected children from a Turkish inbred pedigree. The other novel allele detected in a German patient was a homozygous mutation of the intron 4 donor splice site (c.579 + 1G>A). Patients with GDAP1 mutations displayed severe, early childhood-onset CMT neuropathy with prominent pes equinovarus deformity and impairment of hand muscles. Nerve conduction velocities were between 25 and 35 m/s and peripheral nerve pathology showed axonal as well as demyelinating changes. These findings fitted the definition of intermediate type CMT and further support the view that GDAP1 is vital for both, axonal integrity and Schwann cell properties.

  18. HPGD mutations cause cranioosteoarthropathy but not autosomal dominant digital clubbing.

    PubMed

    Seifert, Wenke; Beninde, Julia; Hoffmann, Katrin; Lindner, Tom H; Bassir, Christian; Aksu, Fuat; Hübner, Christoph; Verbeek, Nienke E; Mundlos, Stefan; Horn, Denise

    2009-12-01

    Cranio-osteoarthropathy, clinically classified as a variant of primary hypertrophic osteoarthropathy, is a very rare autosomal-recessive condition characterized by delayed closure of the cranial sutures and fontanels, digital clubbing, arthropathy, and periostosis. Recently, mutations in the gene HPGD, which encodes the NAD(+)-dependent 15-hydroxyprostaglandin dehydrogenase, were reported in four families affected with primary hypertrophic osteoarthropathy and one family with autosomal-recessive isolated nail clubbing. We report the clinical and molecular findings in four patients from two families affected with cranio-osteoarthropathy and one family with isolated, autosomal dominant digital clubbing. Genome-wide homozygosity mapping identified a locus for cranio-osteoarthropathy harboring the HPGD gene in one affected family. We detected two novel homozygous mutations in HPGD in these families: a missense mutation affecting the NAD(+) binding motif and a frameshift mutation. The clinical presentation in our patients was variable. Digital clubbing and hyperhidrosis were present in all cases. Delayed closure of the cranial sutures and fontanels, periostosis, and arthropathy were not consistent clinical features. No HPGD mutation was detected in a familial case of autosomal dominant isolated digital clubbing. The failure to identify any mutation in a family with an autosomal dominant type of isolated digital clubbing suggests that HPGD is not the major gene for this condition. PMID:19568269

  19. A novel fibrinogen B beta chain frameshift mutation causes congenital afibrinogenaemia.

    PubMed

    Zhang, Jian; Zhao, Xiaojuan; Wang, Zhaoyue; Yu, Ziqiang; Cao, Lijuan; Zhang, Wei; Bai, Xia; Ruan, Changgeng

    2013-07-01

    Congenital afibrinogenaemia is a rare autosomal recessive disorder caused by various mutations within the fibrinogen genes FGA, FGB and FGG. Ins/del mutations in FGB are extremely rare. We report a patient with afibrinogenaemia who suffered from umbilical cord bleeding and repeated bleeding episodes. His plasma fibrinogen levels could not be detected using the Clauss method and immunological methods. Molecular analyses revealed homozygosity in a novel four bases insertion in codon 40 of FGB exon 2 (g. 2833_2834 ins GTTT), which resulted in a truncated 50-residue polypeptide that contained 11 exceptional abnormal residues. In the transient expression experiments, mutant fibrinogen could be detected at higher level than wild-type fibrinogen in COS-7 cell lysates but not in culture media. These results suggest that the homozygous mutation in FGB could be responsible for congenital afibrinogenaemia in this patient. This frameshift mutation could impair fibrinogen assembly and secretion without influencing the protein synthesis.

  20. A homozygous missense variant in type I keratin KRT25 causes autosomal recessive woolly hair

    PubMed Central

    Ansar, Muhammad; Raza, Syed Irfan; Lee, Kwanghyuk; Irfanullah; Shahi, Shamim; Acharya, Anushree; Dai, Hang; Smith, Joshua D; Shendure, Jay; Bamshad, Michael J; Nickerson, Deborah A; Santos-Cortez, Regie Lyn P; Ahmad, Wasim; Leal, Suzanne M

    2016-01-01

    Background Woolly hair (WH) is a hair abnormality that is primarily characterised by tightly curled hair with abnormal growth. Methods In two unrelated consanguineous Pakistani families with non-syndromic autosomal recessive (AR) WH, homozygosity mapping and linkage analysis identified a locus within 17q21.1–q22, which contains the type I keratin gene cluster. A DNA sample from an affected individual from each family underwent exome sequencing. Results A homozygous missense variant c.950T>C (p.(Leu317Pro)) within KRT25 segregated with ARWH in both families, and has a combined maximum two-point LOD score of 7.9 at ϴ=0. The KRT25 variant is predicted to result in disruption of the second α-helical rod domain and the entire protein structure, thus possibly interfering with heterodimerisation of K25 with type II keratins within the inner root sheath (IRS) of the hair follicle and the medulla of the hair shaft. Conclusions Our findings implicate a novel gene involved in human hair abnormality, and are consistent with the curled, fragile hair found in mice with Krt25 mutations, and further support the role of IRS-specific type I keratins in hair follicle development and maintenance of hair texture. PMID:26160856

  1. A defect in the CLIP1 gene (CLIP-170) can cause autosomal recessive intellectual disability

    PubMed Central

    Larti, Farzaneh; Kahrizi, Kimia; Musante, Luciana; Hu, Hao; Papari, Elahe; Fattahi, Zohreh; Bazazzadegan, Niloofar; Liu, Zhe; Banan, Mehdi; Garshasbi, Masoud; Wienker, Thomas F; Ropers, H Hilger; Galjart, Niels; Najmabadi, Hossein

    2015-01-01

    In the context of a comprehensive research project, investigating novel autosomal recessive intellectual disability (ARID) genes, linkage analysis based on autozygosity mapping helped identify an intellectual disability locus on Chr.12q24, in an Iranian family (LOD score=3.7). Next-generation sequencing (NGS) following exon enrichment in this novel interval, detected a nonsense mutation (p.Q1010*) in the CLIP1 gene. CLIP1 encodes a member of microtubule (MT) plus-end tracking proteins, which specifically associates with the ends of growing MTs. These proteins regulate MT dynamic behavior and are important for MT-mediated transport over the length of axons and dendrites. As such, CLIP1 may have a role in neuronal development. We studied lymphoblastoid and skin fibroblast cell lines established from healthy and affected patients. RT-PCR and western blot analyses showed the absence of CLIP1 transcript and protein in lymphoblastoid cells derived from affected patients. Furthermore, immunofluorescence analyses showed MT plus-end staining only in fibroblasts containing the wild-type (and not the mutant) CLIP1 protein. Collectively, our data suggest that defects in CLIP1 may lead to ARID. PMID:24569606

  2. Familial exudative vitreoretinopathy caused by a homozygous mutation in TSPAN12 in a cystic fibrosis infant.

    PubMed

    Savarese, Marco; Spinelli, Elide; Gandolfo, Federico; Lemma, Valentina; Di Fruscio, Giuseppina; Padoan, Rita; Morescalchi, Francesco; D'Agostino, Massimo; Savoldi, Gianfranco; Semeraro, Francesco; Nigro, Vincenzo; Bonatti, Stefano

    2014-09-01

    Familial exudative vitreoretinopathy (FEVR) is a genetic disease affecting the vascularization of the peripheral retina. The clinical manifestations are very heterogeneous, ranging from mildly affected patients, who could present no visual defects, to severe conditions which can also cause complete blindness at birth or in the first decade. FEVR can be inherited in all the three genetic forms: dominant, recessive and X-linked. To date, four genes have been associated with the condition: TSPAN12. NDP. FDZ4 and LRP5. Interestingly, mutations in TSPAN12 have been considered causative of both a dominant and recessive inheritance and a FEVR phenotype sensitive to the number of TSPAN12 mutations has been supposed. Here we describe a case of a female infant affected by cystic fibrosis and by a severe form of exudative vitreoretinopathy. In particular, we have detected the homozygous missense mutation c.668 T > C in TSPAN12. Neither of the heterozygous parents has ocular manifestations of the disease, suggesting a classic recessive mendelian pattern of inheritance.

  3. PRIMA1 mutation: a new cause of nocturnal frontal lobe epilepsy

    PubMed Central

    Hildebrand, Michael S; Tankard, Rick; Gazina, Elena V; Damiano, John A; Lawrence, Kate M; Dahl, Hans-Henrik M; Regan, Brigid M; Shearer, Aiden Eliot; Smith, Richard J H; Marini, Carla; Guerrini, Renzo; Labate, Angelo; Gambardella, Antonio; Tinuper, Paolo; Lichetta, Laura; Baldassari, Sara; Bisulli, Francesca; Pippucci, Tommaso; Scheffer, Ingrid E; Reid, Christopher A; Petrou, Steven; Bahlo, Melanie; Berkovic, Samuel F

    2015-01-01

    Objective Nocturnal frontal lobe epilepsy (NFLE) can be sporadic or autosomal dominant; some families have nicotinic acetylcholine receptor subunit mutations. We report a novel autosomal recessive phenotype in a single family and identify the causative gene. Methods Whole exome sequencing data was used to map the family, thereby narrowing exome search space, and then to identify the mutation. Results Linkage analysis using exome sequence data from two affected and two unaffected subjects showed homozygous linkage peaks on chromosomes 7, 8, 13, and 14 with maximum LOD scores between 1.5 and 1.93. Exome variant filtering under these peaks revealed that the affected siblings were homozygous for a novel splice site mutation (c.93+2T>C) in the PRIMA1 gene on chromosome 14. No additional PRIMA1 mutations were found in 300 other NFLE cases. The c.93+2T>C mutation was shown to lead to skipping of the first coding exon of the PRIMA1 mRNA using a minigene system. Interpretation PRIMA1 is a transmembrane protein that anchors acetylcholinesterase (AChE), an enzyme hydrolyzing acetycholine, to membrane rafts of neurons. PRiMA knockout mice have reduction of AChE and accumulation of acetylcholine at the synapse; our minigene analysis suggests that the c.93+2T>C mutation leads to knockout of PRIMA1. Mutations with gain of function effects in acetylcholine receptor subunits cause autosomal dominant NFLE. Thus, enhanced cholinergic responses are the likely cause of the severe NFLE and intellectual disability segregating in this family, representing the first recessive case to be reported and the first PRIMA1 mutation implicated in disease. PMID:26339676

  4. Non-Recessive Bt Toxin Resistance Conferred by an Intracellular Cadherin Mutation in Field-Selected Populations of Cotton Bollworm

    PubMed Central

    Zhang, Haonan; Wu, Shuwen; Yang, Yihua; Tabashnik, Bruce E.; Wu, Yidong

    2012-01-01

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins have been planted widely to control insect pests, yet evolution of resistance by the pests can reduce the benefits of this approach. Recessive mutations in the extracellular domain of toxin-binding cadherin proteins that confer resistance to Bt toxin Cry1Ac by disrupting toxin binding have been reported previously in three major lepidopteran pests, including the cotton bollworm, Helicoverpa armigera. Here we report a novel allele from cotton bollworm with a deletion in the intracellular domain of cadherin that is genetically linked with non-recessive resistance to Cry1Ac. We discovered this allele in each of three field-selected populations we screened from northern China where Bt cotton producing Cry1Ac has been grown intensively. We expressed four types of cadherin alleles in heterologous cell cultures: susceptible, resistant with the intracellular domain mutation, and two complementary chimeric alleles with and without the mutation. Cells transfected with each of the four cadherin alleles bound Cry1Ac and were killed by Cry1Ac. However, relative to cells transfected with either the susceptible allele or the chimeric allele lacking the intracellular domain mutation, cells transfected with the resistant allele or the chimeric allele containing the intracellular domain mutation were less susceptible to Cry1Ac. These results suggest that the intracellular domain of cadherin is involved in post-binding events that affect toxicity of Cry1Ac. This evidence is consistent with the vital role of the intracellular region of cadherin proposed by the cell signaling model of the mode of action of Bt toxins. Considered together with previously reported data, the results suggest that both pore formation and cell signaling pathways contribute to the efficacy of Bt toxins. PMID:23285292

  5. Tay-Sachs disease-causing mutations and neutral polymorphisms in the Hex A gene.

    PubMed

    Myerowitz, R

    1997-01-01

    Tay-Sachs disease is an autosomal recessive disorder affecting the central nervous system. The disorder results from mutations in the gene encoding the alpha-subunit of beta-hexosaminidase A, a lysosomal enzyme composed of alpha and beta polypeptides. Seventy-eight mutations in the Hex A gene have been described and include 65 single base substitutions, one large and 10 small deletions, and two small insertions. Because these mutations cripple the catalytic activity of beta-hexosaminidase to varying degrees, Tay-Sachs disease displays clinical heterogeneity. Forty-five of the single base substitutions cause missense mutations; 39 of these are disease causing, three are benign but cause a change in phenotype, and three are neutral polymorphisms. Six nonsense mutations and 14 splice site lesions result from single base substitutions, and all but one of the splice site lesions cause a severe form of Tay-Sachs disease. Eight frameshift mutations arise from six deletion- and two insertion-type lesions. One of these insertions, consisting of four bases within exon 11, is found in 80% of the carriers of Tay-Sachs disease from the Ashkenazi Jewish population, an ethnic group that has a 10-fold higher gene frequency for a severe form of the disorder than the general population. A very large deletion, 7.5 kilobases, including all of exon 1 and portions of DNA upstream and downstream from that exon, is the major mutation found in Tay-Sachs disease carriers from the French Canadian population, a geographic isolate displaying an elevated carrier frequency. Most of the other mutations are confined to single pedigrees. Identification of these mutations has permitted more accurate carrier information, prenatal diagnosis, and disease prognosis. In conjunction with a precise tertiary structure of the enzyme, these mutations could be used to gain insight into the structure-function relationships of the lysosomal enzyme.

  6. Transcriptional repression of p53 by parkin and impairment by mutations associated with autosomal recessive juvenile Parkinson’s disease

    PubMed Central

    da Costa, Cristine Alves; Sunyach, Claire; Giaime, Emilie; West, Andrew; Corti, Olga; Brice, Alexis; Safe, Stephen; Abou-Sleiman, Patrick M.; Wood, Nicholas W.; Takahashi, Hitoshi; Goldberg, Mathew S.; Shen, Jie; Checler, Frédéric

    2009-01-01

    Mutations of the ubiquitin ligase parkin account for most autosomal recessive forms of juvenile Parkinson’s disease (AR-JP). Several studies have suggested that parkin possesses DNA-binding and transcriptional activity. We report here that parkin is a p53 transcriptional repressor. First, parkin prevented 6-hydroxydopamine-induced caspase-3 activation in a p53-dependent manner. Concomitantly, parkin reduced p53 expression and activity, an effect abrogated by familial parkin mutations known to either abolish or preserve its ligase activity. ChIP experiments indicate that overexpressed and endogenous parkin interact physically with the p53 promoter and that pathogenic mutations abolish DNA binding to and promoter transactivation of p53. Parkin lowered p53 mRNA levels and repressed p53 promoter transactivation through its Ring1 domain. Conversely, parkin depletion enhanced p53 expression and mRNA levels in fibroblasts and mouse brains, and increased cellular p53 activity and promoter transactivation in cells. Finally, familial parkin missense and deletion mutations enhanced p53 expression in human brains affected by AR-JP. This study reveals a ubiquitin ligase-independent function of parkin in the control of transcription and a functional link between parkin and p53 that is altered by AR-JP mutations. PMID:19801972

  7. DCDC2 Mutations Cause Neonatal Sclerosing Cholangitis.

    PubMed

    Girard, Muriel; Bizet, Albane A; Lachaux, Alain; Gonzales, Emmanuel; Filhol, Emilie; Collardeau-Frachon, Sophie; Jeanpierre, Cécile; Henry, Charline; Fabre, Monique; Viremouneix, Loic; Galmiche, Louise; Debray, Dominique; Bole-Feysot, Christine; Nitschke, Patrick; Pariente, Danièle; Guettier, Catherine; Lyonnet, Stanislas; Heidet, Laurence; Bertholet, Aurelia; Jacquemin, Emmanuel; Henrion-Caude, Alexandra; Saunier, Sophie

    2016-10-01

    Neonatal sclerosing cholangitis (NSC) is a rare biliary disease leading to liver transplantation in childhood. Patients with NSC and ichtyosis have already been identified with a CLDN1 mutation, encoding a tight-junction protein. However, for the majority of patients, the molecular basis of NSC remains unknown. We identified biallelic missense mutations or in-frame deletion in DCDC2 in four affected children. Mutations involve highly conserved amino acids in the doublecortin domains of the protein. In cholangiocytes, DCDC2 protein is normally located in the cytoplasm and cilia, whereas in patients the mutated protein is accumulated in the cytoplasm, absent from cilia, and associated with ciliogenesis defect. This is the first report of DCDC2 mutations in NSC. This data expands the molecular spectrum of NSC, that can be considered as a ciliopathy and also expands the clinical spectrum of the DCDC2 mutations, previously reported in dyslexia, deafness, and nephronophtisis. PMID:27319779

  8. DCDC2 Mutations Cause Neonatal Sclerosing Cholangitis.

    PubMed

    Girard, Muriel; Bizet, Albane A; Lachaux, Alain; Gonzales, Emmanuel; Filhol, Emilie; Collardeau-Frachon, Sophie; Jeanpierre, Cécile; Henry, Charline; Fabre, Monique; Viremouneix, Loic; Galmiche, Louise; Debray, Dominique; Bole-Feysot, Christine; Nitschke, Patrick; Pariente, Danièle; Guettier, Catherine; Lyonnet, Stanislas; Heidet, Laurence; Bertholet, Aurelia; Jacquemin, Emmanuel; Henrion-Caude, Alexandra; Saunier, Sophie

    2016-10-01

    Neonatal sclerosing cholangitis (NSC) is a rare biliary disease leading to liver transplantation in childhood. Patients with NSC and ichtyosis have already been identified with a CLDN1 mutation, encoding a tight-junction protein. However, for the majority of patients, the molecular basis of NSC remains unknown. We identified biallelic missense mutations or in-frame deletion in DCDC2 in four affected children. Mutations involve highly conserved amino acids in the doublecortin domains of the protein. In cholangiocytes, DCDC2 protein is normally located in the cytoplasm and cilia, whereas in patients the mutated protein is accumulated in the cytoplasm, absent from cilia, and associated with ciliogenesis defect. This is the first report of DCDC2 mutations in NSC. This data expands the molecular spectrum of NSC, that can be considered as a ciliopathy and also expands the clinical spectrum of the DCDC2 mutations, previously reported in dyslexia, deafness, and nephronophtisis.

  9. ADCK3, an Ancestral Kinase, Is Mutated in a Form of Recessive Ataxia Associated with Coenzyme Q10 Deficiency

    PubMed Central

    Lagier-Tourenne, Clotilde; Tazir, Meriem; López, Luis Carlos; Quinzii, Catarina M.; Assoum, Mirna; Drouot, Nathalie; Busso, Cleverson; Makri, Samira; Ali-Pacha, Lamia; Benhassine, Traki; Anheim, Mathieu; Lynch, David R.; Thibault, Christelle; Plewniak, Frédéric; Bianchetti, Laurent; Tranchant, Christine; Poch, Olivier; DiMauro, Salvatore; Mandel, Jean-Louis; Barros, Mario H.; Hirano, Michio; Koenig, Michel

    2008-01-01

    Muscle coenzyme Q10 (CoQ10 or ubiquinone) deficiency has been identified in more than 20 patients with presumed autosomal-recessive ataxia. However, mutations in genes required for CoQ10 biosynthetic pathway have been identified only in patients with infantile-onset multisystemic diseases or isolated nephropathy. Our SNP-based genome-wide scan in a large consanguineous family revealed a locus for autosomal-recessive ataxia at chromosome 1q41. The causative mutation is a homozygous splice-site mutation in the aarF-domain-containing kinase 3 gene (ADCK3). Five additional mutations in ADCK3 were found in three patients with sporadic ataxia, including one known to have CoQ10 deficiency in muscle. All of the patients have childhood-onset cerebellar ataxia with slow progression, and three of six have mildly elevated lactate levels. ADCK3 is a mitochondrial protein homologous to the yeast COQ8 and the bacterial UbiB proteins, which are required for CoQ biosynthesis. Three out of four patients tested showed a low endogenous pool of CoQ10 in their fibroblasts or lymphoblasts, and two out of three patients showed impaired ubiquinone synthesis, strongly suggesting that ADCK3 is also involved in CoQ10 biosynthesis. The deleterious nature of the three identified missense changes was confirmed by the introduction of them at the corresponding positions of the yeast COQ8 gene. Finally, a phylogenetic analysis shows that ADCK3 belongs to the family of atypical kinases, which includes phosphoinositide and choline kinases, suggesting that ADCK3 plays an indirect regulatory role in ubiquinone biosynthesis possibly as part of a feedback loop that regulates ATP production. PMID:18319074

  10. 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

  11. Novel Mutation in the PKHD1 Gene Diagnosed Prenatally in a Fetus with Autosomal Recessive Polycystic Kidney Disease

    PubMed Central

    Thakur, Pankaj; Speer, Paul; Rajkovic, Aleksandar

    2014-01-01

    We report a 29-year-old gravida 2, para 0100, who presented at 19 weeks and 4 days of gestation for ultrasound to assess fetal anatomy. Routine midtrimester fetal anatomy ultrasound revealed enlarged, hyperechoic fetal kidneys and normal amniotic fluid index. Follow-up ultrasound at 23 weeks and 5 days revealed persistently enlarged, hyperechoic fetal kidneys. Progressive oligohydramnios was not evident until 29 weeks of gestation, with anhydramnios noted by 35 weeks of gestation. Amniocentesis was performed for karyotype and to search for mutations in the PKHD1 for the presumptive diagnosis of autosomal recessive polycystic kidney disease (ARPKD). In our patient, a maternally inherited, previously reported pathogenic missense mutation in the PKHD1 gene, c.10444C>T, was identified. A second, previously unreported de novo mutation, c.5909-2delA, was also identified. This mutation affects the canonical splice site and is most likely pathogenic. Our case highlights PKHD1 allelic heterogeneity and the importance of genetic testing in the prenatal setting where many other genetic etiologies can phenocopy ARPKD. PMID:25114813

  12. HOXA1 mutations are not a common cause of Möbius syndrome.

    PubMed

    Rankin, Jessica K; Andrews, Caroline; Chan, Wai-Man; Engle, Elizabeth C

    2010-02-01

    The HOXA1-related syndromes result from autosomal-recessive truncating mutations in the homeobox transcription factor, HOXA1. Limited horizontal gaze and sensorineural deafness are the most common features; affected individuals can also have facial weakness, mental retardation, autism, motor disabilities, central hypoventilation, carotid artery, and/or conotruncal heart defects. Möbius syndrome is also phenotypically heterogeneous, with minimal diagnostic criteria of nonprogressive facial weakness and impaired ocular abduction; mental retardation, autism, motor disabilities, additional eye movements restrictions, hearing loss, hypoventilation, and craniofacial, lingual, and limb abnormalities also occur. We asked, given the phenotypic overlap between these syndromes and the variable expressivity of both disorders, whether individuals with Möbius syndrome might harbor mutations in HOXA1. Our results suggest that HOXA1 mutations are not a common cause of sporadic Möbius syndrome in the general population. PMID:20227628

  13. Novel compound heterozygous PIGT mutations caused multiple congenital anomalies-hypotonia-seizures syndrome 3.

    PubMed

    Nakashima, Mitsuko; Kashii, Hirofumi; Murakami, Yoshiko; Kato, Mitsuhiro; Tsurusaki, Yoshinori; Miyake, Noriko; Kubota, Masaya; Kinoshita, Taroh; Saitsu, Hirotomo; Matsumoto, Naomichi

    2014-08-01

    Recessive mutations in genes of the glycosylphosphatidylinositol (GPI)-anchor synthesis pathway have been demonstrated as causative of GPI deficiency disorders associated with intellectual disability, seizures, and diverse congenital anomalies. We performed whole exome sequencing in a patient with progressive encephalopathies and multiple dysmorphism with hypophosphatasia and identified novel compound heterozygous mutations, c.250G>T (p. Glu84*) and c.1342C>T (p. Arg488Trp), in PIGT encoding a subunit of the GPI transamidase complex. The surface expression of GPI-anchored proteins (GPI-APs) on patient granulocytes was lower than that of healthy controls. Transfection of the Arg488Trp mutant PIGT construct, but not the Glu84* mutant, into PIGT-deficient cells partially restored the expression of GPI-APs DAF and CD59. These results indicate that PIGT mutations caused neurological impairment and multiple congenital anomalies in this patient.

  14. Mutations in GNAL cause primary torsion dystonia

    PubMed Central

    Fuchs, Tania; Saunders-Pullman, Rachel; Masuho, Ikuo; Luciano, Marta San; Raymond, Deborah; Factor, Stewart; Lang, Anthony E.; Liang, Tsao-Wei; Trosch, Richard M.; White, Sierra; Ainehsazan, Edmond; Herve, Denis; Sharma, Nutan; Ehrlich, Michelle E.; Martemyanov, Kirill A.; Bressman, Susan B.; Ozelius, Laurie J.

    2012-01-01

    Dystonia is a movement disorder characterized by repetitive twisting muscle contractions and postures1,2. Its molecular pathophysiology is poorly understood, in part due to limited knowledge of the genetic basis of the disorder. Only three genes for primary torsion dystonia (PTD), TOR1A (DYT1)3, THAP1 (DYT6)4, and CIZ15 have been identified. Using exome sequencing in two PTD families we identified a novel causative gene, GNAL, with a nonsense p.S293X mutation resulting in premature stop codon in one family and a missense p.V137M mutation in the other. Screening of GNAL in 39 PTD families, revealed six additional novel mutations in this gene. Impaired function of several of the mutations was shown by bioluminescence resonance energy transfer (BRET) assays. PMID:23222958

  15. A functional alternative splicing mutation in AIRE gene causes autoimmune polyendocrine syndrome type 1.

    PubMed

    Zhang, Junyu; Liu, Hongbin; Liu, Zhiyuan; Liao, Yong; Guo, Luo; Wang, Honglian; He, Lin; Zhang, Xiaodong; Xing, Qinghe

    2013-01-01

    Autoimmune polyendocrine syndrome type 1 (APS-1) is a rare autosomal recessive disease defined by the presence of two of the three conditions: mucocutaneous candidiasis, hypoparathyroidism, and Addison's disease. Loss-of-function mutations of the autoimmune regulator (AIRE) gene have been linked to APS-1. Here we report mutational analysis and functional characterization of an AIRE mutation in a consanguineous Chinese family with APS-1. All exons of the AIRE gene and adjacent exon-intron sequences were amplified by PCR and subsequently sequenced. We identified a homozygous missense AIRE mutation c.463G>A (p.Gly155Ser) in two siblings with different clinical features of APS-1. In silico splice-site prediction and minigene analysis were carried out to study the potential pathological consequence. Minigene splicing analysis and subsequent cDNA sequencing revealed that the AIRE mutation potentially compromised the recognition of the splice donor of intron 3, causing alternative pre-mRNA splicing by intron 3 retention. Furthermore, the aberrant AIRE transcript was identified in a heterozygous carrier of the c.463G>A mutation. The aberrant intron 3-retaining transcript generated a truncated protein (p.G155fsX203) containing the first 154 AIRE amino acids and followed by 48 aberrant amino acids. Therefore, our study represents the first functional characterization of the alternatively spliced AIRE mutation that may explain the pathogenetic role in APS-1.

  16. De novo mutations in KIF1A cause progressive encephalopathy and brain atrophy

    PubMed Central

    Esmaeeli Nieh, Sahar; Madou, Maura R Z; Sirajuddin, Minhajuddin; Fregeau, Brieana; McKnight, Dianalee; Lexa, Katrina; Strober, Jonathan; Spaeth, Christine; Hallinan, Barbara E; Smaoui, Nizar; Pappas, John G; Burrow, Thomas A; McDonald, Marie T; Latibashvili, Mariam; Leshinsky-Silver, Esther; Lev, Dorit; Blumkin, Luba; Vale, Ronald D; Barkovich, Anthony James; Sherr, Elliott H

    2015-01-01

    Objective To determine the cause and course of a novel syndrome with progressive encephalopathy and brain atrophy in children. Methods Clinical whole-exome sequencing was performed for global developmental delay and intellectual disability; some patients also had spastic paraparesis and evidence of clinical regression. Six patients were identified with de novo missense mutations in the kinesin gene KIF1A. The predicted functional disruption of these mutations was assessed in silico to compare the calculated conformational flexibility and estimated efficiency of ATP binding to kinesin motor domains of wild-type (WT) versus mutant alleles. Additionally, an in vitro microtubule gliding assay was performed to assess the effects of de novo dominant, inherited recessive, and polymorphic variants on KIF1A motor function. Results All six subjects had severe developmental delay, hypotonia, and varying degrees of hyperreflexia and spastic paraparesis. Microcephaly, cortical visual impairment, optic neuropathy, peripheral neuropathy, ataxia, epilepsy, and movement disorders were also observed. All six patients had a degenerative neurologic course with progressive cerebral and cerebellar atrophy seen on sequential magnetic resonance imaging scans. Computational modeling of mutant protein structures when compared to WT kinesin showed substantial differences in conformational flexibility and ATP-binding efficiency. The de novo KIF1A mutants were nonmotile in the microtubule gliding assay. Interpretation De novo mutations in KIF1A cause a degenerative neurologic syndrome with brain atrophy. Computational and in vitro assays differentiate the severity of dominant de novo heterozygous versus inherited recessive KIF1A mutations. The profound effect de novo mutations have on axonal transport is likely related to the cause of progressive neurologic impairment in these patients. PMID:26125038

  17. Screening of DFNB3 in Iranian families with autosomal recessive non-syndromic hearing loss reveals a novel pathogenic mutation in the MyTh4 domain of the MYO15A gene in a linked family

    PubMed Central

    Reiisi, Somayeh; Tabatabaiefar, Mohammad Amin; Sanati, Mohammad Hosein; Chaleshtori, Morteza Hashemzadeh

    2016-01-01

    Objective(s): Non-syndromic sensorineural hearing loss (NSHL) is a common disorder affecting approximately 1 in 500 newborns. This type of hearing loss is extremely heterogeneous and includes over 100 loci. Mutations in the GJB2 gene have been implicated in about half of autosomal recessive non-syndromic hearing loss (ARNSHL) cases, making this the most common cause of ARNSHL. For the latter form of deafness, most frequent genes proposed include GJB2, SLC26A4, MYO15A, OTOF, and CDH23 worldwide. Materials and Methods: The aim of the present study was to define the role and frequency of MYO15A gene mutation in Iranian families. In this study 30 Iranian families were enrolled with over three deaf children and negative for GJB2. Then linkage analysis was performed by six DFNB3 short tandem repeat markers. Following that, mutation detection accomplished using DNA sequencing. Results: One family (3.33%) showed linkage to DFNB3 and a novel mutation was identified in the MYO15A gene (c.6442T>A): as the disease-causing mutation. Mutation co-segregated with hearing loss in the family but was not present in the 100 ethnicity-matched controls. Conclusion: Our results confirmed that the hearing loss of the linked Iranian family was caused by a novel missense mutation in the MYO15A gene. This mutation is the first to be reported in the world and affects the first MyTH4 domain of the protein.

  18. SIGMAR1 mutation associated with autosomal recessive Silver-like syndrome

    PubMed Central

    Horga, Alejandro; Tomaselli, Pedro J.; Gonzalez, Michael A.; Laurà, Matilde; Muntoni, Francesco; Manzur, Adnan Y.; Hanna, Michael G.; Blake, Julian C.; Houlden, Henry; Züchner, Stephan

    2016-01-01

    Objective: To describe the genetic and clinical features of a simplex patient with distal hereditary motor neuropathy (dHMN) and lower limb spasticity (Silver-like syndrome) due to a mutation in the sigma nonopioid intracellular receptor–1 gene (SIGMAR1) and review the phenotypic spectrum of mutations in this gene. Methods: We used whole-exome sequencing to investigate the proband. The variants of interest were investigated for segregation in the family using Sanger sequencing. Subsequently, a larger cohort of 16 unrelated dHMN patients was specifically screened for SIGMAR1 mutations. Results: In the proband, we identified a homozygous missense variant (c.194T>A, p.Leu65Gln) in exon 2 of SIGMAR1 as the probable causative mutation. Pathogenicity is supported by evolutionary conservation, in silico analyses, and the strong phenotypic similarities with previously reported cases carrying coding sequence mutations in SIGMAR1. No other mutations were identified in 16 additional patients with dHMN. Conclusions: We suggest that coding sequence mutations in SIGMAR1 present clinically with a combination of dHMN and pyramidal tract signs, with or without spasticity, in the lower limbs. Preferential involvement of extensor muscles of the upper limbs may be a distinctive feature of the disease. These observations should be confirmed in future studies. PMID:27629094

  19. Homozygous SALL1 Mutation Causes a Novel Multiple Congenital Anomaly—Mental Retardation Syndrome

    PubMed Central

    Vodopiutz, Julia; Zoller, Heinz; Fenwick, Aimée L.; Arnhold, Richard; Schmid, Max; Prayer, Daniela; Müller, Thomas; Repa, Andreas; Pollak, Arnold; Aufricht, Christoph; Wilkie, Andrew O.M.; Janecke, Andreas R.

    2013-01-01

    Objective To delineate a novel autosomal recessive multiple congenital anomaly-mental retardation (MCA-MR) syndrome in 2 female siblings of a consanguineous pedigree and to identify the disease-causing mutation. Study design Both siblings were clinically characterized and homozygosity mapping and sequencing of candidate genes were applied. The contribution of nonsense-mediated messenger RNA (mRNA) decay to the expression of mutant mRNA in fibroblasts of a healthy carrier and a control was studied by pyrosequencing. Results We identified the first homozygous SALL1 mutation, c.3160C > T (p.R1054*), in 2 female siblings presenting with multiple congenital anomalies, central nervous system defects, cortical blindness, and absence of psychomotor development (ie, a novel recognizable, autosomal recessive MCA-MR). The mutant SALL1 transcript partially undergoes nonsense-mediated mRNA decay and is present at 43% of the normal transcript level in the fibroblasts of a healthy carrier. Conclusion Previously heterozygous SALL1 mutations and deletions have been associated with dominantly inherited anal-renal-radial-ear developmental anomalies. We identified an allelic recessive SALL1-related MCA-MR. Our findings imply that quantity and quality of SALL1 transcript are important for SALL1 function and determine phenotype, and mode of inheritance, of allelic SALL1-related disorders. This novel MCA-MR emphasizes SALL1 function as critical for normal central nervous system development and warrants a detailed neurologic investigation in all individuals with SALL1 mutations. PMID:23069192

  20. PLEKHM2 mutation leads to abnormal localization of lysosomes, impaired autophagy flux and associates with recessive dilated cardiomyopathy and left ventricular noncompaction.

    PubMed

    Muhammad, Emad; Levitas, Aviva; Singh, Sonia R; Braiman, Alex; Ofir, Rivka; Etzion, Sharon; Sheffield, Val C; Etzion, Yoram; Carrier, Lucie; Parvari, Ruti

    2015-12-20

    Gene mutations, mostly segregating with a dominant mode of inheritance, are important causes of dilated cardiomyopathy (DCM), a disease characterized by enlarged ventricular dimensions, impaired cardiac function, heart failure and high risk of death. Another myocardial abnormality often linked to gene mutations is left ventricular noncompaction (LVNC) characterized by a typical diffuse spongy appearance of the left ventricle. Here, we describe a large Bedouin family presenting with a severe recessive DCM and LVNC. Homozygosity mapping and exome sequencing identified a single gene variant that segregated as expected and was neither reported in databases nor in Bedouin population controls. The PLEKHM2 cDNA2156_2157delAG variant causes the frameshift p.Lys645AlafsTer12 and/or the skipping of exon 11 that results in deletion of 30 highly conserved amino acids. PLEKHM2 is known to interact with several Rabs and with kinesin-1, affecting endosomal trafficking. Accordingly, patients' primary fibroblasts exhibited abnormal subcellular distribution of endosomes marked by Rab5, Rab7 and Rab9, as well as the Golgi apparatus. In addition, lysosomes appeared to be concentrated in the perinuclear region, and autophagy flux was impaired. Transfection of wild-type PLEKHM2 cDNA into patient's fibroblasts corrected the subcellular distribution of the lysosomes, supporting the causal effect of PLEKHM2 mutation. PLEKHM2 joins LAMP-2 and BAG3 as a disease gene altering autophagy resulting in an isolated cardiac phenotype. The association of PLEKHM2 mutation with DCM and LVNC supports the importance of autophagy for normal cardiac function. PMID:26464484

  1. A novel TMPRSS6 mutation that prevents protease auto-activation causes IRIDA

    PubMed Central

    Altamura, Sandro; D'Alessio, Flavia; Selle, Barbara; Muckenthaler, Martina U.

    2010-01-01

    IRIDA (iron-refractory iron-deficiency anaemia) is a rare autosomal-recessive disorder hallmarked by hypochromic microcytic anaemia, low transferrin saturation and high levels of the iron-regulated hormone hepcidin. The disease is caused by mutations in the transmembrane serine protease TMPRSS6 (transmembrane protease serine 6) that prevent inactivation of HJV (haemojuvelin), an activator of hepcidin transcription. In the present paper, we describe a patient with IRIDA who carries a novel mutation (Y141C) in the SEA domain of the TMPRSS6 gene. Functional characterization of the TMPRSS6(Y141C) mutant protein in cultured cells showed that it localizes to similar subcellular compartments as wild-type TMPRSS6 and binds HJV, but fails to auto-catalytically activate itself. As a consequence, hepcidin mRNA expression is increased, causing the clinical symptoms observed in this IRIDA patient. The present study provides important mechanistic insight into how TMPRSS6 is activated. PMID:20704562

  2. A cis-regulatory mutation of PDSS2 causes silky-feather in chickens.

    PubMed

    Feng, Chungang; Gao, Yu; Dorshorst, Ben; Song, Chi; Gu, Xiaorong; Li, Qingyuan; Li, Jinxiu; Liu, Tongxin; Rubin, Carl-Johan; Zhao, Yiqiang; Wang, Yanqiang; Fei, Jing; Li, Huifang; Chen, Kuanwei; Qu, Hao; Shu, Dingming; Ashwell, Chris; Da, Yang; Andersson, Leif; Hu, Xiaoxiang; Li, Ning

    2014-08-01

    Silky-feather has been selected and fixed in some breeds due to its unique appearance. This phenotype is caused by a single recessive gene (hookless, h). Here we map the silky-feather locus to chromosome 3 by linkage analysis and subsequently fine-map it to an 18.9 kb interval using the identical by descent (IBD) method. Further analysis reveals that a C to G transversion located upstream of the prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) gene is causing silky-feather. All silky-feather birds are homozygous for the G allele. The silky-feather mutation significantly decreases the expression of PDSS2 during feather development in vivo. Consistent with the regulatory effect, the C to G transversion is shown to remarkably reduce PDSS2 promoter activity in vitro. We report a new example of feather structure variation associated with a spontaneous mutation and provide new insight into the PDSS2 function.

  3. MBTPS2 mutations cause defective regulated intramembrane proteolysis in X-linked osteogenesis imperfecta

    PubMed Central

    Lindert, Uschi; Cabral, Wayne A.; Ausavarat, Surasawadee; Tongkobpetch, Siraprapa; Ludin, Katja; Barnes, Aileen M.; Yeetong, Patra; Weis, Maryann; Krabichler, Birgit; Srichomthong, Chalurmpon; Makareeva, Elena N.; Janecke, Andreas R.; Leikin, Sergey; Röthlisberger, Benno; Rohrbach, Marianne; Kennerknecht, Ingo; Eyre, David R.; Suphapeetiporn, Kanya; Giunta, Cecilia; Marini, Joan C.; Shotelersuk, Vorasuk

    2016-01-01

    Osteogenesis imperfecta (OI) is a collagen-related bone dysplasia. We identified an X-linked recessive form of OI caused by defects in MBTPS2, which encodes site-2 metalloprotease (S2P). MBTPS2 missense mutations in two independent kindreds with moderate/severe OI cause substitutions at highly conserved S2P residues. Mutant S2P has normal stability, but impaired functioning in regulated intramembrane proteolysis (RIP) of OASIS, ATF6 and SREBP transcription factors, consistent with decreased proband secretion of type I collagen. Further, hydroxylation of the collagen lysine residue (K87) critical for crosslinking is reduced in proband bone tissue, consistent with decreased lysyl hydroxylase 1 in proband osteoblasts. Reduced collagen crosslinks presumptively undermine bone strength. Also, proband osteoblasts have broadly defective differentiation. These mutations provide evidence that RIP plays a fundamental role in normal bone development. PMID:27380894

  4. A cis-Regulatory Mutation of PDSS2 Causes Silky-Feather in Chickens

    PubMed Central

    Feng, Chungang; Gao, Yu; Dorshorst, Ben; Song, Chi; Gu, Xiaorong; Li, Qingyuan; Li, Jinxiu; Liu, Tongxin; Rubin, Carl-Johan; Zhao, Yiqiang; Wang, Yanqiang; Fei, Jing; Li, Huifang; Chen, Kuanwei; Qu, Hao; Shu, Dingming; Ashwell, Chris; Da, Yang; Andersson, Leif; Hu, Xiaoxiang; Li, Ning

    2014-01-01

    Silky-feather has been selected and fixed in some breeds due to its unique appearance. This phenotype is caused by a single recessive gene (hookless, h). Here we map the silky-feather locus to chromosome 3 by linkage analysis and subsequently fine-map it to an 18.9 kb interval using the identical by descent (IBD) method. Further analysis reveals that a C to G transversion located upstream of the prenyl (decaprenyl) diphosphate synthase, subunit 2 (PDSS2) gene is causing silky-feather. All silky-feather birds are homozygous for the G allele. The silky-feather mutation significantly decreases the expression of PDSS2 during feather development in vivo. Consistent with the regulatory effect, the C to G transversion is shown to remarkably reduce PDSS2 promoter activity in vitro. We report a new example of feather structure variation associated with a spontaneous mutation and provide new insight into the PDSS2 function. PMID:25166907

  5. Nature and frequency of mutations in the argininosuccinate synthetase gene that cause classical citrullinemia.

    PubMed

    Kobayashi, K; Kakinoki, H; Fukushige, T; Shaheen, N; Terazono, H; Saheki, T

    1995-10-01

    Citrullinemia is an autosomal recessive disorder caused by a genetic deficiency of argininosuccinate synthetase (ASS). So far 20 mutations in ASS mRNA have been identified in human classical citrullinemia, including 14 single base changes causing missense mutations in the coding sequence of the enzyme, 4 mutations associated with an absence of exons 5, 6, 7, or 13 in mRNA, 1 mutation with a deletion of the first 7 bases in exon 16 (which is caused by abnormal splicing), and 1 mutation with an insertion of 37 bases between the exon 15 and 16 regions in mRNA. In order to identify the abnormality in the ASS gene causing the exon 7 and 13 deletion mutations and the 37-base insertion mutation between exons 15 and 16 in mRNA, and to establish a DNA diagnostic test, we isolated and sequenced the genomic DNA surrounding each exon. The absence of exon 7 or 13 in ASS mRNA resulted from abnormal splicing caused by a single base change in the intron region: IVS-6(-2) (a transition of A to G at the second nucleotide position within the 3' splice cleavage site of intron 6) and IVS-13(+5) (a transition of G to A at the fifth nucleotide position within the 5' splice cleavage site of intron 13), respectively. The IVS-6(-2) mutation resulted in the creation of an MspI restriction site. DNA diagnostic analysis of 33 Japanese alleles with classical citrullinemia showed that 19 alleles had the IVS-6(-2) mutation (over 50% of the mutated alleles in Japanese patients). It was thus confirmed that one mutation is predominant in Japan. This differs from the situation in the USA where there is far greater heterogeneity. The insertion mutation in mRNA on the other hand resulted from abnormal splicing caused by a 13-bp deletion at the splice-junction between exon 15 and intron 15. The deletion had a short direct repeat (CTCAGG) at the breakpoint junction and presumably resulted from slipped mispairing. PMID:7557970

  6. A homozygous mutation in a consanguineous family consolidates the role of ALDH1A3 in autosomal recessive microphthalmia.

    PubMed

    Roos, L; Fang, M; Dali, C; Jensen, H; Christoffersen, N; Wu, B; Zhang, J; Xu, R; Harris, P; Xu, X; Grønskov, K; Tümer, Z

    2014-09-01

    Anomalies of eye development can lead to the rare eye malformations microphthalmia and anophthalmia (small or absent ocular globes), which are genetically very heterogeneous. Several genes have been associated with microphthalmia and anophthalmia, and exome sequencing has contributed to the identification of new genes. Very recently, homozygous variations within ALDH1A3 have been associated with autosomal recessive microphthalmia with or without cysts or coloboma, and with variable subphenotypes of developmental delay/autism spectrum disorder in eight families. In a consanguineous family where three of the five siblings were affected with microphthalmia/coloboma, we identified a novel homozygous missense mutation in ALDH1A3 using exome sequencing. Of the three affected siblings, one had intellectual disability and one had intellectual disability and autism, while the last one presented with normal development. This study contributes further to the description of the clinical spectrum associated with ALDH1A3 mutations, and illustrates the interfamilial clinical variation observed in individuals with ALDH1A3 mutations.

  7. Identification of two novel mutations in CDHR1 in consanguineous Spanish families with autosomal recessive retinal dystrophy

    PubMed Central

    Nikopoulos, Konstantinos; Avila-Fernandez, Almudena; Corton, Marta; Lopez-Molina, Maria Isabel; Perez-Carro, Raquel; Bontadelli, Lara; Di Gioia, Silvio Alessandro; Zurita, Olga; Garcia-Sandoval, Blanca; Rivolta, Carlo; Ayuso, Carmen

    2015-01-01

    Inherited retinal dystrophies present extensive phenotypic and genetic heterogeneity, posing a challenge for patients’ molecular and clinical diagnoses. In this study, we wanted to clinically characterize and investigate the molecular etiology of an atypical form of autosomal recessive retinal dystrophy in two consanguineous Spanish families. Affected members of the respective families exhibited an array of clinical features including reduced visual acuity, photophobia, defective color vision, reduced or absent ERG responses, macular atrophy and pigmentary deposits in the peripheral retina. Genetic investigation included autozygosity mapping coupled with exome sequencing in the first family, whereas autozygome-guided candidate gene screening was performed by means of Sanger DNA sequencing in the second family. Our approach revealed nucleotide changes in CDHR1; a homozygous missense variant (c.1720C > G, p.P574A) and a homozygous single base transition (c.1485 + 2T > C) affecting the canonical 5’ splice site of intron 13, respectively. Both changes co-segregated with the disease and were absent among cohorts of unrelated control individuals. To date, only five mutations in CDHR1 have been identified, all resulting in premature stop codons leading to mRNA nonsense mediated decay. Our work reports two previously unidentified homozygous mutations in CDHR1 further expanding the mutational spectrum of this gene. PMID:26350383

  8. Cerebro-retinal microangiopathy with calcifications and cysts due to recessive mutations in the CTC1 gene.

    PubMed

    Bisserbe, A; Tertian, G; Buffet, C; Turhan, A; Lambotte, O; Nasser, G; Alvin, P; Tardieu, M; Riant, F; Bergametti, F; Tournier-Lasserve, E; Denier, C

    2015-05-01

    Cerebro-retinal microangiopathy with calcifications and cysts (CRMCC) or Coats plus syndrome is a pleiotropic disorder affecting the eyes, brain, bone and gastrointestinal tract. Its primary pathogenesis involves small vessel obliterative microangiopathy. Recently, autosomal recessively inherited mutations in CTC1 have been reported in CRMCC patients. We herein report an adolescent referred to our hospital following new seizures in a context of an undefined multisystem disorder. Cerebral imaging disclosed asymmetrical leukopathy, intracranial calcifications and cysts. In addition, he presented other typical CRMCC features i.e. a history of intrauterine growth retardation, skeletal demineralization and osteopenia, bilateral exudative vitreo-retinopathy reminiscent of Coats disease, recurrent gastrointestinal hemorrhages secondary to watermelon stomach and variceal bleeding of the esophagus due to idiopathic portal hypertension and telangiectatic and angiodysplasic changes in the small intestine and colon, and anemia due to recurrent bleeding and bone marrow abnormalities. The patient was diagnosed with Coats plus syndrome. CTC1 gene screening confirmed the diagnosis with the identification of heterozygous deleterious mutations. CRMCC due to CTC1 mutations has a broad clinical expressivity. Our case report illustrates the main possible associated phenotypes and their complications, demonstrating the need for a careful etiological search in order to initiate appropriate therapeutic and preventive measures.

  9. A COL7A1 Mutation Causes Dystrophic Epidermolysis Bullosa in Rotes Höhenvieh Cattle

    PubMed Central

    Menoud, Annie; Welle, Monika; Tetens, Jens; Lichtner, Peter; Drögemüller, Cord

    2012-01-01

    We identified a congenital mechanobullous skin disorder in six calves on a single farm of an endangered German cattle breed in 2010. The condition presented as a large loss of skin distal to the fetlocks and at the mucosa of the muzzle. All affected calves were euthanized on humane grounds due to the severity, extent and progression of the skin and oral lesions. Examination of skin samples under light microscopy revealed detachment of the epidermis from the dermis at the level of the dermo epidermal junction, leading to the diagnosis of a subepidermal bullous dermatosis such as epidermolysis bullosa. The pedigree was consistent with monogenic autosomal recessive inheritance. We localized the causative mutation to an 18 Mb interval on chromosome 22 by homozygosity mapping. The COL7A1 gene encoding collagen type VII alpha 1 is located within this interval and COL7A1 mutations have been shown to cause inherited dystrophic epidermolysis bullosa (DEB) in humans. A SNP in the bovine COL7A1 exon 49 (c.4756C>T) was perfectly associated with the observed disease. The homozygous mutant T/T genotype was exclusively present in affected calves and their parents were heterozygous C/T confirming the assumed recessive mode of inheritance. All known cases and genotyped carriers were related to a single cow, which is supposed to be the founder animal. The mutant T allele was absent in 63 animals from 24 cattle breeds. The identified mutation causes a premature stop codon which leads to a truncated protein representing a complete loss of COL7A1 function (p.R1586*). We thus have identified a candidate causative mutation for this genetic disease using only three cases to unravel its molecular basis. Selection against this mutation can now be used to eliminate the mutant allele from the Rotes Höhenvieh breed. PMID:22715415

  10. Biallelic RFX6 mutations can cause childhood as well as neonatal onset diabetes mellitus

    PubMed Central

    Sansbury, Francis H; Kirel, Birgül; Caswell, Richard; Lango Allen, Hana; Flanagan, Sarah E; Hattersley, Andrew T; Ellard, Sian; Shaw-Smith, Charles J

    2015-01-01

    Neonatal diabetes is a highly genetically heterogeneous disorder. There are over 20 distinct syndromic and non-syndromic forms, including dominant, recessive and X-linked subtypes. Biallelic truncating or mis-sense mutations in the DNA-binding domain of the RFX6 transcription factor cause an autosomal recessive, syndromic form of neonatal diabetes previously described as Mitchell–Riley syndrome. In all, eight cases have been reported, with the age at onset of diabetes in the first 2 weeks of life. Here we report two individuals born to double first cousins in whom intestinal atresias consistent with a diagnosis of Mitchell–Riley syndrome were diagnosed at birth, but in whom diabetes did not present until the ages of 3 and 6 years. Novel compound heterozygous RFX6 nonsense mutations (p.Arg726X/p.Arg866X) were identified at the 3′ end of the gene. The later onset of diabetes in these patients may be due to incomplete inactivation of RFX6. Genetic testing for RFX6 mutations should be considered in patients presenting with intestinal atresias in the absence of neonatal diabetes. PMID:26264437

  11. Congenital myopathy caused by a novel missense mutation in the CFL2 gene.

    PubMed

    Ockeloen, C W; Gilhuis, H J; Pfundt, R; Kamsteeg, E J; Agrawal, P B; Beggs, A H; Dara Hama-Amin, A; Diekstra, A; Knoers, N V A M; Lammens, M; van Alfen, N

    2012-07-01

    Nemaline myopathy and myofibrillar myopathy are heterogeneous myopathies that both comprise early-onset forms. We present two sisters from a consanguineous Iraqi Kurdish family with predominant axial and limb girdle weakness. Muscle biopsies showed features of both nemaline myopathy and myofibrillar myopathy. We performed homozygosity mapping in both siblings using an Affymetrix 250K Nspl SNP array. One of the overlapping homozygous regions harbored the gene CFL2. Because a mutation in CFL2 was identified in a family with nemaline myopathy, we performed sequence analysis of the gene and a novel homozygous missense mutation in exon 2 (c.19G>A, p.Val7Met) of CFL2 was identified in both siblings. CFL2 encodes the protein cofilin-2, which plays an important role in regulation of sarcomeric actin filaments. To our knowledge, this is the second family in which a mutation in CFL2 causes an autosomal recessive form of congenital myopathy with features of both nemaline and myofibrillar myopathy. Given the clinical variability and the multitude of histological features of congenital myopathies, CFL2 sequence analysis should be considered in patients presenting with an autosomal recessive form of congenital myopathy. PMID:22560515

  12. Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations

    PubMed Central

    Nishiguchi, Koji M.; Fujita, Kosuke; Nakazawa, Toru; Alswaid, Abdulrahman; Albalwi, Mohammed A.; Kim, Ok-Hwa; Cho, Tae-Joon; Lim, Gye-Yeon; Isidor, Bertrand; David, Albert; Rustad, Cecilie F.; Merckoll, Else; Westvik, Jostein; Stattin, Eva-Lena; Grigelioniene, Giedre; Kou, Ikuyo; Nakajima, Masahiro; Ohashi, Hirohumi; Smithson, Sarah; Matsumoto, Naomichi; Nishimura, Gen; Ikegawa, Shiro

    2016-01-01

    Axial spondylometaphyseal dysplasia (axial SMD) is an autosomal recessive disease characterized by dysplasia of axial skeleton and retinal dystrophy. We conducted whole exome sequencing and identified C21orf2 (chromosome 21 open reading frame 2) as a disease gene for axial SMD. C21orf2 mutations have been recently found to cause isolated retinal degeneration and Jeune syndrome. We found a total of five biallelic C21orf2 mutations in six families out of nine: three missense and two splicing mutations in patients with various ethnic backgrounds. The pathogenic effects of the splicing (splice-site and branch-point) mutations were confirmed on RNA level, which showed complex patterns of abnormal splicing. C21orf2 mutations presented with a wide range of skeletal phenotypes, including cupped and flared anterior ends of ribs, lacy ilia and metaphyseal dysplasia of proximal femora. Analysis of patients without C21orf2 mutation indicated genetic heterogeneity of axial SMD. Functional data in chondrocyte suggest C21orf2 is implicated in cartilage differentiation. C21orf2 protein was localized to the connecting cilium of the cone and rod photoreceptors, confirming its significance in retinal function. Our study indicates that axial SMD is a member of a unique group of ciliopathy affecting skeleton and retina. PMID:26974433

  13. The Polg Mutator Phenotype Does Not Cause Dopaminergic Neurodegeneration in DJ-1-Deficient Mice.

    PubMed

    Hauser, David N; Primiani, Christopher T; Langston, Rebekah G; Kumaran, Ravindran; Cookson, Mark R

    2015-01-01

    Mutations in the DJ-1 gene cause autosomal recessive parkinsonism in humans. Several mouse models of DJ-1 deficiency have been developed, but they do not have dopaminergic neuron cell death in the substantia nigra pars compacta (SNpc). Mitochondrial DNA (mtDNA) damage occurs frequently in the aged human SNpc but not in the mouse SNpc. We hypothesized that the reason DJ-1-deficient mice do not have dopaminergic cell death is due to an absence of mtDNA damage. We tested this hypothesis by crossing DJ-1-deficient mice with mice that have similar amounts of mtDNA damage in their SNpc as aged humans (Polg mutator mice). At 1 year of age, we counted the amount of SNpc dopaminergic neurons in the mouse brains using both colorimetric and fluorescent staining followed by unbiased stereology. No evidence of dopaminergic cell death was observed in DJ-1-deficient mice with the Polg mutator mutation. Furthermore, we did not observe any difference in dopaminergic terminal immunostaining in the striatum of these mice. Finally, we did not observe any changes in the amount of GFAP-positive astrocytes in the SNpc of these mice, indicative of a lack of astrogliosis. Altogether, our findings demonstrate the DJ-1-deficient mice, Polg mutator mice, and DJ-1-deficient Polg mutator mice have intact nigrastriatal pathways. Thus, the lack of mtDNA damage in the mouse SNpc does not underlie the absence of dopaminergic cell death in DJ-1-deficient mice.

  14. Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations.

    PubMed

    Wang, Zheng; Iida, Aritoshi; Miyake, Noriko; Nishiguchi, Koji M; Fujita, Kosuke; Nakazawa, Toru; Alswaid, Abdulrahman; Albalwi, Mohammed A; Kim, Ok-Hwa; Cho, Tae-Joon; Lim, Gye-Yeon; Isidor, Bertrand; David, Albert; Rustad, Cecilie F; Merckoll, Else; Westvik, Jostein; Stattin, Eva-Lena; Grigelioniene, Giedre; Kou, Ikuyo; Nakajima, Masahiro; Ohashi, Hirohumi; Smithson, Sarah; Matsumoto, Naomichi; Nishimura, Gen; Ikegawa, Shiro

    2016-01-01

    Axial spondylometaphyseal dysplasia (axial SMD) is an autosomal recessive disease characterized by dysplasia of axial skeleton and retinal dystrophy. We conducted whole exome sequencing and identified C21orf2 (chromosome 21 open reading frame 2) as a disease gene for axial SMD. C21orf2 mutations have been recently found to cause isolated retinal degeneration and Jeune syndrome. We found a total of five biallelic C21orf2 mutations in six families out of nine: three missense and two splicing mutations in patients with various ethnic backgrounds. The pathogenic effects of the splicing (splice-site and branch-point) mutations were confirmed on RNA level, which showed complex patterns of abnormal splicing. C21orf2 mutations presented with a wide range of skeletal phenotypes, including cupped and flared anterior ends of ribs, lacy ilia and metaphyseal dysplasia of proximal femora. Analysis of patients without C21orf2 mutation indicated genetic heterogeneity of axial SMD. Functional data in chondrocyte suggest C21orf2 is implicated in cartilage differentiation. C21orf2 protein was localized to the connecting cilium of the cone and rod photoreceptors, confirming its significance in retinal function. Our study indicates that axial SMD is a member of a unique group of ciliopathy affecting skeleton and retina. PMID:26974433

  15. Exome Sequencing Identifies INPPL1 Mutations as a Cause of Opsismodysplasia

    PubMed Central

    Huber, Céline; Faqeih, Eissa Ali; Bartholdi, Deborah; Bole-Feysot, Christine; Borochowitz, Zvi; Cavalcanti, Denise P.; Frigo, Amandine; Nitschke, Patrick; Roume, Joelle; Santos, Heloísa G.; Shalev, Stavit A.; Superti-Furga, Andrea; Delezoide, Anne-Lise; Le Merrer, Martine; Munnich, Arnold; Cormier-Daire, Valérie

    2013-01-01

    Opsismodysplasia (OPS) is a severe autosomal-recessive chondrodysplasia characterized by pre- and postnatal micromelia with extremely short hands and feet. The main radiological features are severe platyspondyly, squared metacarpals, delayed skeletal ossification, and metaphyseal cupping. In order to identify mutations causing OPS, a total of 16 cases (7 terminated pregnancies and 9 postnatal cases) from 10 unrelated families were included in this study. We performed exome sequencing in three cases from three unrelated families and only one gene was found to harbor mutations in all three cases: inositol polyphosphate phosphatase-like 1 (INPPL1). Screening INPPL1 in the remaining cases identified a total of 12 distinct INPPL1 mutations in the 10 families, present at the homozygote state in 7 consanguinous families and at the compound heterozygote state in the 3 remaining families. Most mutations (6/12) resulted in premature stop codons, 2/12 were splice site, and 4/12 were missense mutations located in the catalytic domain, 5-phosphatase. INPPL1 belongs to the inositol-1,4,5-trisphosphate 5-phosphatase family, a family of signal-modulating enzymes that govern a plethora of cellular functions by regulating the levels of specific phosphoinositides. Our finding of INPPL1 mutations in OPS, a severe spondylodysplastic dysplasia with major growth plate disorganization, supports a key and specific role of this enzyme in endochondral ossification. PMID:23273569

  16. Axial Spondylometaphyseal Dysplasia Is Caused by C21orf2 Mutations.

    PubMed

    Wang, Zheng; Iida, Aritoshi; Miyake, Noriko; Nishiguchi, Koji M; Fujita, Kosuke; Nakazawa, Toru; Alswaid, Abdulrahman; Albalwi, Mohammed A; Kim, Ok-Hwa; Cho, Tae-Joon; Lim, Gye-Yeon; Isidor, Bertrand; David, Albert; Rustad, Cecilie F; Merckoll, Else; Westvik, Jostein; Stattin, Eva-Lena; Grigelioniene, Giedre; Kou, Ikuyo; Nakajima, Masahiro; Ohashi, Hirohumi; Smithson, Sarah; Matsumoto, Naomichi; Nishimura, Gen; Ikegawa, Shiro

    2016-01-01

    Axial spondylometaphyseal dysplasia (axial SMD) is an autosomal recessive disease characterized by dysplasia of axial skeleton and retinal dystrophy. We conducted whole exome sequencing and identified C21orf2 (chromosome 21 open reading frame 2) as a disease gene for axial SMD. C21orf2 mutations have been recently found to cause isolated retinal degeneration and Jeune syndrome. We found a total of five biallelic C21orf2 mutations in six families out of nine: three missense and two splicing mutations in patients with various ethnic backgrounds. The pathogenic effects of the splicing (splice-site and branch-point) mutations were confirmed on RNA level, which showed complex patterns of abnormal splicing. C21orf2 mutations presented with a wide range of skeletal phenotypes, including cupped and flared anterior ends of ribs, lacy ilia and metaphyseal dysplasia of proximal femora. Analysis of patients without C21orf2 mutation indicated genetic heterogeneity of axial SMD. Functional data in chondrocyte suggest C21orf2 is implicated in cartilage differentiation. C21orf2 protein was localized to the connecting cilium of the cone and rod photoreceptors, confirming its significance in retinal function. Our study indicates that axial SMD is a member of a unique group of ciliopathy affecting skeleton and retina.

  17. Obstruction of adaptation in diploids by recessive, strongly deleterious alleles

    PubMed Central

    Assaf, Zoe June; Petrov, Dmitri A.; Blundell, Jamie R.

    2015-01-01

    Recessive deleterious mutations are common, causing many genetic disorders in humans and producing inbreeding depression in the majority of sexually reproducing diploids. The abundance of recessive deleterious mutations in natural populations suggests they are likely to be present on a chromosome when a new adaptive mutation occurs, yet the dynamics of recessive deleterious hitchhikers and their impact on adaptation remains poorly understood. Here we model how a recessive deleterious mutation impacts the fate of a genetically linked dominant beneficial mutation. The frequency trajectory of the adaptive mutation in this case is dramatically altered and results in what we have termed a “staggered sweep.” It is named for its three-phased trajectory: (i) Initially, the two linked mutations have a selective advantage while rare and will increase in frequency together, then (ii), at higher frequencies, the recessive hitchhiker is exposed to selection and can cause a balanced state via heterozygote advantage (the staggered phase), and (iii) finally, if recombination unlinks the two mutations, then the beneficial mutation can complete the sweep to fixation. Using both analytics and simulations, we show that strongly deleterious recessive mutations can substantially decrease the probability of fixation for nearby beneficial mutations, thus creating zones in the genome where adaptation is suppressed. These mutations can also significantly prolong the number of generations a beneficial mutation takes to sweep to fixation, and cause the genomic signature of selection to resemble that of soft or partial sweeps. We show that recessive deleterious variation could impact adaptation in humans and Drosophila. PMID:25941393

  18. Forty-eight novel mutations causing biotinidase deficiency.

    PubMed

    Procter, Melinda; Wolf, Barry; Mao, Rong

    2016-03-01

    Biotinidase deficiency is an autosomal recessively inherited disorder that results in the inability to recycle the vitamin biotin and is characterized by neurological and cutaneous symptoms. The symptoms can be ameliorated or prevented by administering pharmacological doses of biotin. Since 2008, approximately 300 samples have been submitted to ARUP's Molecular Sequencing Laboratory for biotinidase mutation analysis. Of these, 48 novel alterations in the biotinidase gene have been identified. Correlating the individual's serum enzymatic activity with the genotype, we have been able to determine the effect of the novel alteration on enzyme activity and, thereby, determine its likelihood of being pathogenic in 44 of these individuals. The novel mutations and uncertain alterations have been added to the database established by ARUP (http://arup.utah.edu/database/BTD/BTD_welcome.phps) to help clinicians make decisions about management and to better counsel their patients based on their genotypes. PMID:26810761

  19. WDR73 mutations cause infantile neurodegeneration and variable glomerular kidney disease

    PubMed Central

    Vodopiutz, Julia; Seidl, Rainer; Prayer, Daniela; Khan, M. Imran; Mayr, Johannes A.; Streubel, Berthold; Steiß, Jens-Oliver; Hahn, Andreas; Csaicsich, Dagmar; Castro, Christel; Assoum, Mirna; Müller, Thomas; Wieczorek, Dagmar; Mancini, Grazia M. S.; Sadowski, Carolin E.; Levy, Nicolas; Mégarbané, André; Godbole, Koumudi; Schanze, Denny; Hildebrandt, Friedhelm; Delague, Valérie; Janecke, Andreas R.; Zenker, Martin

    2015-01-01

    Infantile-onset cerebellar atrophy (CA) is a clinically and genetically heterogeneous trait. Galloway-Mowat syndrome (GMS) is a rare autosomal recessive disease, characterized by microcephaly with brain anomalies including CA in some cases, intellectual disability, and early-infantile-onset nephrotic syndrome. Very recently, WDR73 deficiency was identified as the cause of GMS in five individuals. To evaluate the role of WDR73 mutations as a cause of GMS and other forms of syndromic CA, we performed Sanger or exome sequencing in 51 unrelated patients with CA and variable brain anomalies and in 40 unrelated patients with a diagnosis of GMS. We identified 10 patients from three CA and from two GMS families with WDR73 mutations including the original family described with CA, mental retardation, optic atrophy and skin abnormalities (CAMOS). There were five novel mutations, of which two were truncating and three were missense mutations affecting highly conserved residues. Individuals carrying homozygous WDR73 mutations mainly presented with a pattern of neurological and neuroimaging findings as well as intellectual disability, while kidney involvement was variable. We document postnatal onset of CA, a retinopathy, basal ganglia degeneration, and short stature as novel features of WDR73-related disease, and define WDR73-related disease as a new entity of infantile neurodegeneration. PMID:26123727

  20. 8-oxoguanine causes spontaneous de novo germline mutations in mice

    PubMed Central

    Ohno, Mizuki; Sakumi, Kunihiko; Fukumura, Ryutaro; Furuichi, Masato; Iwasaki, Yuki; Hokama, Masaaki; Ikemura, Toshimichi; Tsuzuki, Teruhisa; Gondo, Yoichi; Nakabeppu, Yusaku

    2014-01-01

    Spontaneous germline mutations generate genetic diversity in populations of sexually reproductive organisms, and are thus regarded as a driving force of evolution. However, the cause and mechanism remain unclear. 8-oxoguanine (8-oxoG) is a candidate molecule that causes germline mutations, because it makes DNA more prone to mutation and is constantly generated by reactive oxygen species in vivo. We show here that endogenous 8-oxoG caused de novo spontaneous and heritable G to T mutations in mice, which occurred at different stages in the germ cell lineage and were distributed throughout the chromosomes. Using exome analyses covering 40.9 Mb of mouse transcribed regions, we found increased frequencies of G to T mutations at a rate of 2 × 10−7 mutations/base/generation in offspring of Mth1/Ogg1/Mutyh triple knockout (TOY-KO) mice, which accumulate 8-oxoG in the nuclear DNA of gonadal cells. The roles of MTH1, OGG1, and MUTYH are specific for the prevention of 8-oxoG-induced mutation, and 99% of the mutations observed in TOY-KO mice were G to T transversions caused by 8-oxoG; therefore, we concluded that 8-oxoG is a causative molecule for spontaneous and inheritable mutations of the germ lineage cells. PMID:24732879

  1. Appearance of recessive lethal mutations in derivatives of an unstable X{sup Z} chromosome of Drosophila melanogaster

    SciTech Connect

    Yurchenko, N.N.; Koryakov, D.E.; Zakharov, I.K.

    1995-09-01

    An X{sup Z} chromosome isolated from a natural population of Drosophila melanogaster is characterized by spontaneous mutability of the genes yellow, white, and singed and the appearance of chromosomal rearrangements. In mutant lines derived from the line carrying the X{sup Z} chromosome that had one, two, or three unstable vision mutations (markers), the rate of appearance of sex-linked lethal mutations was analyzed. This rate was shown to increase with an increase in the number of markers in a line. This phenomenon, termed {open_quotes}marker induction,{close_quotes} might explain the phenotypic homogeneity of natural Drosophila populations. Spontaneous lethal mutations were mapped, and their nonrandom distribution along the X{sup Z} chromosome was shown. Along with common {open_quotes}hot spot{close_quotes} sites of lethal mutations, the derivatives of the X{sup Z} chromosomes had their own specific sites for lethal mutations. In some cases, the appearance of lethal mutations was accompanied by the formation of inversions in the X{sup Z} chromosome. The lethal destabilization of the X{sup Z} derivatives, caused by selection for accumulation of visible mutations, is associated with an increase in the number of hot spots for nuclear mutations. Presumably, these hot spots are hot sites for the transposition of mobile genetic elements. 18 refs., 4 figs., 3 tabs.

  2. Update of the spectrum of GJB2 gene mutations in 152 Moroccan families with autosomal recessive nonsyndromic hearing loss.

    PubMed

    Bakhchane, Amina; Bousfiha, Amale; Charoute, Hicham; Salime, Sara; Detsouli, Mustapha; Snoussi, Khalid; Nadifi, Sellama; Kabine, Mostafa; Rouba, Hassan; Dehbi, Hind; Roky, Rachida; Charif, Majida; Barakat, Abdelhamid

    2016-06-01

    Deafness is one of the most common genetic diseases in humans and is subject to important genetic heterogeneity. The most common cause of non syndromic hearing loss (NSHL) is mutations in the GJB2 gene. This study aims to update and evaluate the spectrum of GJB2 allele variants in 152 Moroccan multiplex families with non syndromic hearing loss. Seven different mutations were detected: c.35delG, p.V37I, p.E47X, p.G200R, p.Del120E, p.R75Q, the last three mutations were described for the first time in Moroccan deaf patients, in addition to a novel nonsense mutation, the c.385G>T which is not referenced in any database. Sixty six families (43.42%) have mutations in the coding region of GJB2, while the homozygous c.35delG mutation still to date the most represented 51/152 (33.55%). The analysis of the geographical distribution of mutations located in GJB2 gene showed more allelic heterogeneity in the north and center compared to the south of Morocco. Our results showed that the GJB2 gene is a major contributor to non syndromic hearing loss in Morocco. Thus, this report of the GJB2 mutations spectrum all over Morocco has an important implication for establishing a suitable molecular diagnosis. PMID:27169813

  3. ELOVL5 mutations cause spinocerebellar ataxia 38.

    PubMed

    Di Gregorio, Eleonora; Borroni, Barbara; Giorgio, Elisa; Lacerenza, Daniela; Ferrero, Marta; Lo Buono, Nicola; Ragusa, Neftj; Mancini, Cecilia; Gaussen, Marion; Calcia, Alessandro; Mitro, Nico; Hoxha, Eriola; Mura, Isabella; Coviello, Domenico A; Moon, Young-Ah; Tesson, Christelle; Vaula, Giovanna; Couarch, Philippe; Orsi, Laura; Duregon, Eleonora; Papotti, Mauro Giulio; Deleuze, Jean-François; Imbert, Jean; Costanzi, Chiara; Padovani, Alessandro; Giunti, Paola; Maillet-Vioud, Marcel; Durr, Alexandra; Brice, Alexis; Tempia, Filippo; Funaro, Ada; Boccone, Loredana; Caruso, Donatella; Stevanin, Giovanni; Brusco, Alfredo

    2014-08-01

    Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal-dominant neurodegenerative disorders involving the cerebellum and 23 different genes. We mapped SCA38 to a 56 Mb region on chromosome 6p in a SCA-affected Italian family by whole-genome linkage analysis. Targeted resequencing identified a single missense mutation (c.689G>T [p.Gly230Val]) in ELOVL5. Mutation screening of 456 independent SCA-affected individuals identified the same mutation in two further unrelated Italian families. Haplotyping showed that at least two of the three families shared a common ancestor. One further missense variant (c.214C>G [p.Leu72Val]) was found in a French family. Both missense changes affect conserved amino acids, are predicted to be damaging by multiple bioinformatics tools, and were not identified in ethnically matched controls or within variant databases. ELOVL5 encodes an elongase involved in the synthesis of polyunsaturated fatty acids of the ω3 and ω6 series. Arachidonic acid and docosahexaenoic acid, two final products of the enzyme, were reduced in the serum of affected individuals. Immunohistochemistry on control mice and human brain demonstrated high levels in Purkinje cells. In transfection experiments, subcellular localization of altered ELOVL5 showed a perinuclear distribution with a signal increase in the Golgi compartment, whereas the wild-type showed a widespread signal in the endoplasmic reticulum. SCA38 and SCA34 are examples of SCAs due to mutations in elongase-encoding genes, emphasizing the importance of fatty-acid metabolism in neurological diseases.

  4. A Hereditary Enteropathy Caused by Mutations in the SLCO2A1 Gene, Encoding a Prostaglandin Transporter

    PubMed Central

    Esaki, Motohiro; Hirano, Atsushi; Kubokura, Naoya; Asano, Kouichi; Kochi, Shuji; Yanai, Shunichi; Fuyuno, Yuta; Shimamura, Katsuyoshi; Hosoe, Naoki; Ogata, Haruhiko; Watanabe, Takashi; Aoyagi, Kunihiko; Ooi, Hidehisa; Watanabe, Kenji; Yasukawa, Shigeyoshi; Hirai, Fumihito; Matsui, Toshiyuki; Iida, Mitsuo; Yao, Tsuneyoshi; Hibi, Toshifumi; Kosaki, Kenjiro; Kanai, Takanori; Kitazono, Takanari; Matsumoto, Takayuki

    2015-01-01

    Previously, we proposed a rare autosomal recessive inherited enteropathy characterized by persistent blood and protein loss from the small intestine as chronic nonspecific multiple ulcers of the small intestine (CNSU). By whole-exome sequencing in five Japanese patients with CNSU and one unaffected individual, we found four candidate mutations in the SLCO2A1 gene, encoding a prostaglandin transporter. The pathogenicity of the mutations was supported by segregation analysis and genotyping data in controls. By Sanger sequencing of the coding regions, 11 of 12 other CNSU patients and 2 of 603 patients with a diagnosis of Crohn’s disease were found to have homozygous or compound heterozygous SLCO2A1 mutations. In total, we identified recessive SLCO2A1 mutations located at seven sites. Using RT-PCR, we demonstrated that the identified splice-site mutations altered the RNA splicing, and introduced a premature stop codon. Tracer prostaglandin E2 uptake analysis showed that the mutant SLCO2A1 protein for each mutation exhibited impaired prostaglandin transport. Immunohistochemistry and immunofluorescence analyses revealed that SLCO2A1 protein was expressed on the cellular membrane of vascular endothelial cells in the small intestinal mucosa in control subjects, but was not detected in affected individuals. These findings indicate that loss-of-function mutations in the SLCO2A1 gene encoding a prostaglandin transporter cause the hereditary enteropathy CNSU. We suggest a more appropriate nomenclature of “chronic enteropathy associated with SLCO2A1 gene” (CEAS). PMID:26539716

  5. Whole-exome sequencing in a single proband reveals a mutation in the CHST8 gene in autosomal recessive peeling skin syndrome.

    PubMed

    Cabral, Rita M; Kurban, Mazen; Wajid, Muhammad; Shimomura, Yutaka; Petukhova, Lynn; Christiano, Angela M

    2012-04-01

    Generalized peeling skin syndrome (PSS) is an autosomal recessive genodermatosis characterized by lifelong, continuous shedding of the upper epidermis. Using whole-genome homozygozity mapping and whole-exome sequencing, we identified a novel homozygous missense mutation (c.229C>T, R77W) within the CHST8 gene, in a large consanguineous family with non-inflammatory PSS type A. CHST8 encodes a Golgi transmembrane N-acetylgalactosamine-4-O-sulfotransferase (GalNAc4-ST1), which we show by immunofluorescence staining to be expressed throughout normal epidermis. A colorimetric assay for total sulfated glycosaminoglycan (GAG) quantification, comparing human keratinocytes (CCD1106 KERTr) expressing wild type and mutant recombinant GalNAc4-ST1, revealed decreased levels of total sulfated GAGs in cells expressing mutant GalNAc4-ST1, suggesting loss of function. Western blotting revealed lower expression levels of mutant recombinant GalNAc4-ST1 compared to wild type, suggesting that accelerated degradation may result in loss of function, leading to PSS type A. This is the first report describing a mutation as the cause of PSS type A.

  6. Ataxia and Hypogonadotropic Hypogonadism with Intrafamilial Variability Caused by RNF216 Mutation.

    PubMed

    Alqwaifly, Mohammed; Bohlega, Saeed

    2016-06-15

    Gordon Holmes syndrome (GHS) is a distinct phenotype of autosomal recessive cerebellar ataxia, characterized by ataxia, dementia, reproductive defects and hypogonadism; it has been recently found to be associated with RNF216 mutation. We performed whole-exome sequencing and filtered the resulting novel variants by the coordinates of the shared autozygome. We identified a novel splicing variant in RNF216 that is likely to abolish the canonical splice site at the junction of exon/intron 13 (NM_207111.3:c.2061G>A). We herein report two patients with GHS caused by a novel RNF216 mutation as the first follow up report on RNF216-related GHS, and show interfamilial variability of phenotype supporting the previously reported RNF216-related cases. PMID:27441066

  7. Equine diseases caused by known genetic mutations.

    PubMed

    Finno, Carrie J; Spier, Sharon J; Valberg, Stephanie J

    2009-03-01

    The recent development of equine genome maps by the equine genome community and the complete sequencing of the horse genome performed at the Broad Institute have accelerated the pace of genetic discovery. This review focuses on genetic diseases in the horse for which a mutation is currently known, including hyperkalemic periodic paralysis, severe combined immunodeficiency, overo lethal white syndrome, junctional epidermolysis bullosa, glycogen branching enzyme deficiency, malignant hyperthermia, hereditary equine regional dermal asthenia, and polysaccharide storage myopathy. Emphasis is placed on the prevalence, clinical signs, etiology, diagnosis, treatment and prognosis for each disease.

  8. Mutations in ZBTB20 cause Primrose syndrome.

    PubMed

    Cordeddu, Viviana; Redeker, Bert; Stellacci, Emilia; Jongejan, Aldo; Fragale, Alessandra; Bradley, Ted E J; Anselmi, Massimiliano; Ciolfi, Andrea; Cecchetti, Serena; Muto, Valentina; Bernardini, Laura; Azage, Meron; Carvalho, Daniel R; Espay, Alberto J; Male, Alison; Molin, Anna-Maja; Posmyk, Renata; Battisti, Carla; Casertano, Alberto; Melis, Daniela; van Kampen, Antoine; Baas, Frank; Mannens, Marcel M; Bocchinfuso, Gianfranco; Stella, Lorenzo; Tartaglia, Marco; Hennekam, Raoul C

    2014-08-01

    Primrose syndrome and 3q13.31 microdeletion syndrome are clinically related disorders characterized by tall stature, macrocephaly, intellectual disability, disturbed behavior and unusual facial features, with diabetes, deafness, progressive muscle wasting and ectopic calcifications specifically occurring in the former. We report that missense mutations in ZBTB20, residing within the 3q13.31 microdeletion syndrome critical region, underlie Primrose syndrome. This finding establishes a genetic link between these disorders and delineates the impact of ZBTB20 dysregulation on development, growth and metabolism.

  9. Mutation in FAM134B causing severe hereditary sensory neuropathy

    PubMed Central

    Murphy, Sinead M; Davidson, Gabrielle L; Brandner, Sebastian; Houlden, Henry; Reilly, Mary M

    2013-01-01

    The hereditary sensory and autonomic neuropathies (HSAN) are rare inherited neuropathies presenting with sensory loss and complications, including ulcers, infections, osteomyelitis and amputations. Usually, sensory symptoms predominate although motor involvement can occur. Autonomic features may be minimal (then hereditary sensory neuropathy, HSN, is preferred). HSAN has been classified into five subtypes depending on clinical presentation.1 Hereditary sensory and autonomic neuropathy II (HSANII or HSNII) is an early onset, autosomal recessive sensory neuropathy with ulcero-mutilating complications due to mutations in the HSN2 isoform of the WNK1 gene.2 Recently, a similar phenotype was described in a Saudi-Arabian family, and a homozygous nonsense mutation found in a new gene, FAM134B (family with sequence similarity 134, member B), encoding a newly identified Golgi protein. The index case in this family was initially thought to have leprosy. Three additional families (out of 75 patients) with similar phenotypes were found to have homozygous loss of function mutations in FAM134B.3 Here, we report the clinical and pathological findings in a further patient with HSNII due to a homozygous mutation in FAM134B. PMID:21115472

  10. Loss of heterozygosity in human ductal breast tumors indicates a recessive mutation on chromosome 13

    SciTech Connect

    Lundberg, C.; Skoog, L.; Cavenee, W.K.; Nordenskjoeld, M.

    1987-04-01

    The genotypes at chromosomal loci defined by recombinant DNA probes revealing restriction fragment length polymorphisms were determined in constitutional and tumor tissue from 10 cases of ductal breast cancer: eight premenopausal females and two males. Somatic loss of constitutional heterozygosity was observed at loci on chromosome 13 in primary tumor tissue from three females and one male. In two cases, specific loss of heterozygosity at three distinct genetic loci along the length of the chromosome was observed. In another case, concurrent loss of alleles at loci on chromosomes 2, 13, 14, and 20 was detected, whereas a fourth case showed loss of heterozygosity for chromosomes 5 and 13. In each instance, the data were consistent with loss of one of the homologous chromosomes by mitotic nondisjunction. Analysis of loci on several other chromosomes showed retention of constitutional heterozygosity suggesting the relative specificity of the events. In contrast, similar analyses of other breast cancers, including comedocarcinoma, medullary carcinoma, and juvenile secretory carcinoma, showed no loss of alleles at loci on chromosome 13. These data indicate that the pathogenesis of ductal breast cancer may, in a substantial proportion of cases, involve unmasking of a recessive locus on chromosome 13 and suggest the involvement of such a locus in heritable forms of this disease.

  11. Mutations in C4orf26, encoding a peptide with in vitro hydroxyapatite crystal nucleation and growth activity, cause amelogenesis imperfecta.

    PubMed

    Parry, David A; Brookes, Steven J; Logan, Clare V; Poulter, James A; El-Sayed, Walid; Al-Bahlani, Suhaila; Al Harasi, Sharifa; Sayed, Jihad; Raïf, El Mostafa; Shore, Roger C; Dashash, Mayssoon; Barron, Martin; Morgan, Joanne E; Carr, Ian M; Taylor, Graham R; Johnson, Colin A; Aldred, Michael J; Dixon, Michael J; Wright, J Tim; Kirkham, Jennifer; Inglehearn, Chris F; Mighell, Alan J

    2012-09-01

    Autozygosity mapping and clonal sequencing of an Omani family identified mutations in the uncharacterized gene, C4orf26, as a cause of recessive hypomineralized amelogenesis imperfecta (AI), a disease in which the formation of tooth enamel fails. Screening of a panel of 57 autosomal-recessive AI-affected families identified eight further families with loss-of-function mutations in C4orf26. C4orf26 encodes a putative extracellular matrix acidic phosphoprotein expressed in the enamel organ. A mineral nucleation assay showed that the protein's phosphorylated C terminus has the capacity to promote nucleation of hydroxyapatite, suggesting a possible function in enamel mineralization during amelogenesis.

  12. Mutations in Dnaaf1 and Lrrc48 Cause Hydrocephalus, Laterality Defects, and Sinusitis in Mice.

    PubMed

    Ha, Seungshin; Lindsay, Anna M; Timms, Andrew E; Beier, David R

    2016-01-01

    We have previously described a forward genetic screen in mice for abnormalities of brain development. Characterization of two hydrocephalus mutants by whole-exome sequencing after whole-genome SNP mapping revealed novel recessive mutations in Dnaaf1 and Lrrc48 Mouse mutants of these two genes have not been previously reported. The Dnaaf1 mutant carries a mutation at the splice donor site of exon 4, which results in abnormal transcripts. The Lrrc48 mutation is a missense mutation at a highly conserved leucine residue, which is also associated with a decrease in Lrrc48 transcription. Both Dnaaf1 and Lrrc48 belong to a leucine-rich repeat-containing protein family and are components of the ciliary axoneme. Their Chlamydomonas orthologs are known to be required for normal ciliary beat frequency or flagellar waveform, respectively. Some Dnaaf1 or Lrrc48 homozygote mutants displayed laterality defects, suggesting a motile cilia defect in the embryonic node. Mucus accumulation and neutrophil infiltration in the maxillary sinuses suggested sinusitis. Dnaaf1 mutants showed postnatal lethality, and none survived to weaning age. Lrrc48 mutants survive to adulthood, but had male infertility. ARL13B immunostaining showed the presence of motile cilia in the mutants, and the distal distribution of DNAH9 in the axoneme of upper airway motile cilia appeared normal. The phenotypic abnormalities suggest that mutations in Dnaaf1 and Lrrc48 cause defects in motile cilia function. PMID:27261005

  13. X-linked VACTERL with hydrocephalus syndrome: further delineation of the phenotype caused by FANCB mutations.

    PubMed

    McCauley, Joanna; Masand, Navta; McGowan, Ruth; Rajagopalan, Sulekha; Hunter, Alasdair; Michaud, Jacques L; Gibson, Kate; Robertson, Jeremy; Vaz, Fiona; Abbs, Stephen; Holden, Simon T

    2011-10-01

    X-linked VACTERL-hydrocephalus syndrome (X-linked VACTERL-H) is a rare disorder caused by mutations in the gene FANCB which underlies Fanconi Anemia (FA) complementation group B. Cells from affected males have increased chromosome breakage on exposure to DNA cross-linking agents. Only five FANCB mutations found in six affected males, including an affected uncle and nephew, have been reported. We have identified FANCB mutations in a further four affected families. The VACTERL-H phenotype segregates as an X-linked recessive trait in three of these. Each mutation is predicted to truncate the FANCB open reading frame and results in highly skewed X-inactivation in unaffected carrier females. Phenotypic data were available on six affected males. Comparison of the clinical findings in our patients with published clinical data (total 12 patients) shows that ventriculomegaly, bilateral absent thumbs and radii, vertebral defects, renal agenesis, and growth retardation are the major phenotypic signs in affected males. Less frequent are brain, pituitary, ear and eye malformations, gastrointestinal atresias (esophageal, duodenal and anal), tracheoesophageal fistula, lung segmentation defects, and small genitalia. Three of six of our patients survived the perinatal period. One boy lived up to 2 years 10 months but developed aplastic anemia and died of renal failure. These data show that loss-of-function FANCB mutations result in a recognizable, multiple malformation phenotype in hemizygous males for which we propose clinical criteria to aid diagnosis. PMID:21910217

  14. X-linked VACTERL with hydrocephalus syndrome: further delineation of the phenotype caused by FANCB mutations.

    PubMed

    McCauley, Joanna; Masand, Navta; McGowan, Ruth; Rajagopalan, Sulekha; Hunter, Alasdair; Michaud, Jacques L; Gibson, Kate; Robertson, Jeremy; Vaz, Fiona; Abbs, Stephen; Holden, Simon T

    2011-10-01

    X-linked VACTERL-hydrocephalus syndrome (X-linked VACTERL-H) is a rare disorder caused by mutations in the gene FANCB which underlies Fanconi Anemia (FA) complementation group B. Cells from affected males have increased chromosome breakage on exposure to DNA cross-linking agents. Only five FANCB mutations found in six affected males, including an affected uncle and nephew, have been reported. We have identified FANCB mutations in a further four affected families. The VACTERL-H phenotype segregates as an X-linked recessive trait in three of these. Each mutation is predicted to truncate the FANCB open reading frame and results in highly skewed X-inactivation in unaffected carrier females. Phenotypic data were available on six affected males. Comparison of the clinical findings in our patients with published clinical data (total 12 patients) shows that ventriculomegaly, bilateral absent thumbs and radii, vertebral defects, renal agenesis, and growth retardation are the major phenotypic signs in affected males. Less frequent are brain, pituitary, ear and eye malformations, gastrointestinal atresias (esophageal, duodenal and anal), tracheoesophageal fistula, lung segmentation defects, and small genitalia. Three of six of our patients survived the perinatal period. One boy lived up to 2 years 10 months but developed aplastic anemia and died of renal failure. These data show that loss-of-function FANCB mutations result in a recognizable, multiple malformation phenotype in hemizygous males for which we propose clinical criteria to aid diagnosis.

  15. Mutations in Dnaaf1 and Lrrc48 Cause Hydrocephalus, Laterality Defects, and Sinusitis in Mice

    PubMed Central

    Ha, Seungshin; Lindsay, Anna M.; Timms, Andrew E.; Beier, David R.

    2016-01-01

    We have previously described a forward genetic screen in mice for abnormalities of brain development. Characterization of two hydrocephalus mutants by whole-exome sequencing after whole-genome SNP mapping revealed novel recessive mutations in Dnaaf1 and Lrrc48. Mouse mutants of these two genes have not been previously reported. The Dnaaf1 mutant carries a mutation at the splice donor site of exon 4, which results in abnormal transcripts. The Lrrc48 mutation is a missense mutation at a highly conserved leucine residue, which is also associated with a decrease in Lrrc48 transcription. Both Dnaaf1 and Lrrc48 belong to a leucine-rich repeat-containing protein family and are components of the ciliary axoneme. Their Chlamydomonas orthologs are known to be required for normal ciliary beat frequency or flagellar waveform, respectively. Some Dnaaf1 or Lrrc48 homozygote mutants displayed laterality defects, suggesting a motile cilia defect in the embryonic node. Mucus accumulation and neutrophil infiltration in the maxillary sinuses suggested sinusitis. Dnaaf1 mutants showed postnatal lethality, and none survived to weaning age. Lrrc48 mutants survive to adulthood, but had male infertility. ARL13B immunostaining showed the presence of motile cilia in the mutants, and the distal distribution of DNAH9 in the axoneme of upper airway motile cilia appeared normal. The phenotypic abnormalities suggest that mutations in Dnaaf1 and Lrrc48 cause defects in motile cilia function. PMID:27261005

  16. Aquaporin-2: new mutations responsible for autosomal-recessive nephrogenic diabetes insipidus—update and epidemiology

    PubMed Central

    El Tarazi, Abdulah; Matar, Jessica; Lussier, Yoann; Arthus, Marie-Françoise; Lonergan, Michèle; Bockenhauer, Detlef; Bissonnette, Pierre

    2012-01-01

    It is clinically useful to distinguish between two types of hereditary nephrogenic diabetes insipidus (NDI): a ‘pure’ type characterized by loss of water only and a complex type characterized by loss of water and ions. Patients with congenital NDI bearing mutations in the vasopressin 2 receptor gene, AVPR2, or in the aquaporin-2 gene, AQP2, have a pure NDI phenotype with loss of water but normal conservation of sodium, potassium, chloride and calcium. Patients with hereditary hypokalemic salt-losing tubulopathies have a complex phenotype with loss of water and ions. They have polyhydramnios, hypercalciuria and hypo- or isosthenuria and were found to bear KCNJ1 (ROMK) and SLC12A1 (NKCC2) mutations. Patients with polyhydramnios, profound polyuria, hyponatremia, hypochloremia, metabolic alkalosis and sensorineural deafness were found to bear BSND mutations. These clinical phenotypes demonstrate the critical importance of the proteins ROMK, NKCC2 and Barttin to transfer NaCl in the medullary interstitium and thereby to generate, together with urea, a hypertonic milieu. This editorial describes two new developments: (i) the genomic information provided by the sequencing of the AQP2 gene is key to the routine care of these patients, and, as in other genetic diseases, reduces health costs and provides psychological benefits to patients and families and (ii) the expression of AQP2 mutants in Xenopus oocytes and in polarized renal tubular cells recapitulates the clinical phenotypes and reveals a continuum from severe loss of function with urinary osmolalities <150 mOsm/kg H2O to milder defects with urine osmolalities >200 mOsm/kg H2O. PMID:26069764

  17. Aquaporin-2: new mutations responsible for autosomal-recessive nephrogenic diabetes insipidus-update and epidemiology.

    PubMed

    Bichet, Daniel G; El Tarazi, Abdulah; Matar, Jessica; Lussier, Yoann; Arthus, Marie-Françoise; Lonergan, Michèle; Bockenhauer, Detlef; Bissonnette, Pierre

    2012-06-01

    It is clinically useful to distinguish between two types of hereditary nephrogenic diabetes insipidus (NDI): a 'pure' type characterized by loss of water only and a complex type characterized by loss of water and ions. Patients with congenital NDI bearing mutations in the vasopressin 2 receptor gene, AVPR2, or in the aquaporin-2 gene, AQP2, have a pure NDI phenotype with loss of water but normal conservation of sodium, potassium, chloride and calcium. Patients with hereditary hypokalemic salt-losing tubulopathies have a complex phenotype with loss of water and ions. They have polyhydramnios, hypercalciuria and hypo- or isosthenuria and were found to bear KCNJ1 (ROMK) and SLC12A1 (NKCC2) mutations. Patients with polyhydramnios, profound polyuria, hyponatremia, hypochloremia, metabolic alkalosis and sensorineural deafness were found to bear BSND mutations. These clinical phenotypes demonstrate the critical importance of the proteins ROMK, NKCC2 and Barttin to transfer NaCl in the medullary interstitium and thereby to generate, together with urea, a hypertonic milieu. This editorial describes two new developments: (i) the genomic information provided by the sequencing of the AQP2 gene is key to the routine care of these patients, and, as in other genetic diseases, reduces health costs and provides psychological benefits to patients and families and (ii) the expression of AQP2 mutants in Xenopus oocytes and in polarized renal tubular cells recapitulates the clinical phenotypes and reveals a continuum from severe loss of function with urinary osmolalities <150 mOsm/kg H2O to milder defects with urine osmolalities >200 mOsm/kg H2O. PMID:26069764

  18. Somatic Activating PIK3CA Mutations Cause Venous Malformation.

    PubMed

    Limaye, Nisha; Kangas, Jaakko; Mendola, Antonella; Godfraind, Catherine; Schlögel, Matthieu J; Helaers, Raphael; Eklund, Lauri; Boon, Laurence M; Vikkula, Miikka

    2015-12-01

    Somatic mutations in TEK, the gene encoding endothelial cell tyrosine kinase receptor TIE2, cause more than half of sporadically occurring unifocal venous malformations (VMs). Here, we report that somatic mutations in PIK3CA, the gene encoding the catalytic p110α subunit of PI3K, cause 54% (27 out of 50) of VMs with no detected TEK mutation. The hotspot mutations c.1624G>A, c.1633G>A, and c.3140A>G (p.Glu542Lys, p.Glu545Lys, and p.His1047Arg), frequent in PIK3CA-associated cancers, overgrowth syndromes, and lymphatic malformation (LM), account for >92% of individuals who carry mutations. Like VM-causative mutations in TEK, the PIK3CA mutations cause chronic activation of AKT, dysregulation of certain important angiogenic factors, and abnormal endothelial cell morphology when expressed in human umbilical vein endothelial cells (HUVECs). The p110α-specific inhibitor BYL719 restores all abnormal phenotypes tested, in PIK3CA- as well as TEK-mutant HUVECs, demonstrating that they operate via the same pathogenic pathways. Nevertheless, significant genotype-phenotype correlations in lesion localization and histology are observed between individuals with mutations in PIK3CA versus TEK, pointing to gene-specific effects. PMID:26637981

  19. New Mutation in the Mouse Xpd/Ercc2 Gene Leads to Recessive Cataracts

    PubMed Central

    Kunze, Sarah; Dalke, Claudia; Fuchs, Helmut; Klaften, Matthias; Rössler, Ute; Hornhardt, Sabine; Gomolka, Maria; Puk, Oliver; Sabrautzki, Sibylle; Kulka, Ulrike; Hrabě de Angelis, Martin; Graw, Jochen

    2015-01-01

    Cataracts are the major eye disorder and have been associated mainly with mutations in lens-specific genes, but cataracts are also frequently associated with complex syndromes. In a large-scale high-throughput ENU mutagenesis screen we analyzed the offspring of paternally treated C3HeB/FeJ mice for obvious dysmorphologies. We identified a mutant suffering from rough coat and small eyes only in homozygotes; homozygous females turned out to be sterile. The mutation was mapped to chromosome 7 between the markers 116J6.1 and D7Mit294;4 other markers within this interval did not show any recombination among 160 F2-mutants. The critical interval (8.6 Mb) contains 3 candidate genes (Apoe, Six5, Opa3); none of them showed a mutation. Using exome sequencing, we identified a c.2209T>C mutation in the Xpd/Ercc2 gene leading to a Ser737Pro exchange. During embryonic development, the mutant eyes did not show major changes. Postnatal histological analyses demonstrated small cortical vacuoles; later, cortical cataracts developed. Since XPD/ERCC2 is involved in DNA repair, we checked also for the presence of the repair-associated histone γH2AX in the lens. During the time, when primary lens fiber cell nuclei are degraded, γH2AX was strongly expressed in the cell nuclei; later, it demarcates clearly the border of the lens cortex to the organelle-free zone. Moreover, we analyzed also whether seemingly healthy heterozygotes might be less efficient in repair of DNA damage induced by ionizing radiation than wild types. Peripheral lymphocytes irradiated by 1Gy Cs137 showed 6 hrs after irradiation significantly more γH2AX foci in heterozygotes than in wild types. These findings demonstrate the importance of XPD/ERCC2 not only for lens fiber cell differentiation, but also for the sensitivity to ionizing radiation. Based upon these data, we hypothesize that variations in the human XPD/ERCC2 gene might increase the susceptibility for several disorders besides Xeroderma pigmentosum in

  20. De Novo GMNN Mutations Cause Autosomal-Dominant Primordial Dwarfism Associated with Meier-Gorlin Syndrome

    PubMed Central

    Burrage, Lindsay C.; Charng, Wu-Lin; Eldomery, Mohammad K.; Willer, Jason R.; Davis, Erica E.; Lugtenberg, Dorien; Zhu, Wenmiao; Leduc, Magalie S.; Akdemir, Zeynep C.; Azamian, Mahshid; Zapata, Gladys; Hernandez, Patricia P.; Schoots, Jeroen; de Munnik, Sonja A.; Roepman, Ronald; Pearring, Jillian N.; Jhangiani, Shalini; Katsanis, Nicholas; Vissers, Lisenka E.L.M.; Brunner, Han G.; Beaudet, Arthur L.; Rosenfeld, Jill A.; Muzny, Donna M.; Gibbs, Richard A.; Eng, Christine M.; Xia, Fan; Lalani, Seema R.; Lupski, James R.; Bongers, Ernie M.H.F.; Yang, Yaping

    2015-01-01

    Meier-Gorlin syndrome (MGS) is a genetically heterogeneous primordial dwarfism syndrome known to be caused by biallelic loss-of-function mutations in one of five genes encoding pre-replication complex proteins: ORC1, ORC4, ORC6, CDT1, and CDC6. Mutations in these genes cause disruption of the origin of DNA replication initiation. To date, only an autosomal-recessive inheritance pattern has been described in individuals with this disorder, with a molecular etiology established in about three-fourths of cases. Here, we report three subjects with MGS and de novo heterozygous mutations in the 5′ end of GMNN, encoding the DNA replication inhibitor geminin. We identified two truncating mutations in exon 2 (the 1st coding exon), c.16A>T (p.Lys6∗) and c.35_38delTCAA (p.Ile12Lysfs∗4), and one missense mutation, c.50A>G (p.Lys17Arg), affecting the second-to-last nucleotide of exon 2 and possibly RNA splicing. Geminin is present during the S, G2, and M phases of the cell cycle and is degraded during the metaphase-anaphase transition by the anaphase-promoting complex (APC), which recognizes the destruction box sequence near the 5′ end of the geminin protein. All three GMNN mutations identified alter sites 5′ to residue Met28 of the protein, which is located within the destruction box. We present data supporting a gain-of-function mechanism, in which the GMNN mutations result in proteins lacking the destruction box and hence increased protein stability and prolonged inhibition of replication leading to autosomal-dominant MGS. PMID:26637980

  1. Multi-systemic involvement in NGLY1-related disorder caused by two novel mutations.

    PubMed

    Heeley, Jennifer; Shinawi, Marwan

    2015-04-01

    NGLY1-related disorder is a newly described autosomal recessive condition characterized by neurological, hepatic, ophthalmological findings and associated with dysmorphic features, constipation and scoliosis. It is caused by mutations in NGLY1, which encodes an enzyme, N-glycanase 1, involved in deglycosylation of glycoproteins, an essential step in the endoplasmic reticulum-associated degradation (ERAD) pathway. The disorder has been described in eight patients. We investigated the molecular basis and phenotype of NGLY1-related disorder in an additional patient. The proband is a 14-year-old who presented in early infancy with profound hypotonia and elevated transaminases. Liver biopsy showed lipid accumulation with dilated endoplasmic reticulum. He exhibited global developmental delay, acquired microcephaly, seizures, involuntary body movements, muscle atrophy, absent reflexes, and poor growth. He had multiple procedures for lacrimal duct stenosis and strabismus and had intractable blepharitis. He had severe osteopenia and persistent hypocholesterolemia. Whole exome sequencing revealed two novel variants in NGLY1: a truncating mutation, c.347C > G (p.S116X), and a splicing mutation, c.881 + 5G (p.IVS5 + 5G>T), predicted to abolish the splice donor site of exon 5. This study, along with previously reported cases, suggests that mutations in NGLY1 cause a recognizable phenotype and targeted sequencing should be considered in patients with typical presentation. This study expands the molecular spectrum of NGLY1-related condition and suggests that osteopenia and hypocholesterolemia may be part of the phenotype. PMID:25707956

  2. Mutations in COL6A3 Cause Severe and Mild Phenotypes of Ullrich Congenital Muscular Dystrophy

    PubMed Central

    Demir, Ercan; Sabatelli, Patrizia; Allamand, Valérie; Ferreiro, Ana; Moghadaszadeh, Behzad; Makrelouf, Mohamed; Topaloglu, Haluk; Echenne, Bernard; Merlini, Luciano; Guicheney, Pascale

    2002-01-01

    Ullrich congenital muscular dystrophy (UCMD) is an autosomal recessive disorder characterized by generalized muscular weakness, contractures of multiple joints, and distal hyperextensibility. Homozygous and compound heterozygous mutations of COL6A2 on chromosome 21q22 have recently been shown to cause UCMD. We performed a genomewide screening with microsatellite markers in a consanguineous family with three sibs affected with UCMD. Linkage of the disease to chromosome 2q37 was found in this family and in two others. We analyzed COL6A3, which encodes the α3 chain of collagen VI, and identified one homozygous mutation per family. In family I, the three sibs carried an A→G transition in the splice-donor site of intron 29 (6930+5A→G), leading to the skipping of exon 29, a partial reduction of collagen VI in muscle biopsy, and an intermediate phenotype. In family II, the patient had an unusual mild phenotype, despite a nonsense mutation, R465X, in exon 5. Analysis of the patient’s COL6A3 transcripts showed the presence of various mRNA species—one of which lacked several exons, including the exon containing the nonsense mutation. The deleted splice variant encodes collagen molecules that have a shorter N-terminal domain but that may assemble with other chains and retain a functional role. This could explain the mild phenotype of the patient who was still ambulant at age 18 years and who showed an unusual combination of hyperlaxity and finger contractures. In family III, the patient had a nonsense mutation, R2342X, causing absence of collagen VI in muscle and fibroblasts, and a severe phenotype, as has been described in patients with UCMD. Mutations in COL6A3 are described in UCMD for the first time and illustrate the wide spectrum of phenotypes which can be caused by collagen VI deficiency. PMID:11992252

  3. The heartstrings mutation in zebrafish causes heart/fin Tbx5 deficiency syndrome.

    PubMed

    Garrity, Deborah M; Childs, Sarah; Fishman, Mark C

    2002-10-01

    Holt-Oram syndrome is one of the autosomal dominant human "heart-hand" disorders, with a combination of upper limb malformations and cardiac defects. Holt-Oram syndrome is caused by mutations in the TBX5 gene, a member of a large family of T-box transcription factors that play important roles in cell-type specification and morphogenesis. In a screen for mutations affecting zebrafish cardiac function, we isolated the recessive lethal mutant heartstrings, which lacks pectoral fins and exhibits severe cardiac dysfunction, beginning with a slow heart rate and progressing to a stretched, non-functional heart. We mapped and cloned the heartstrings mutation and find it to encode the zebrafish ortholog of the TBX5 gene. The heartstrings mutation causes premature termination at amino acid 316. Homozygous mutant embryos never develop pectoral fin buds and do not express several markers of early fin differentiation. The total absence of any fin bud differentiation distinguishes heartstrings from most other mutations that affect zebrafish fin development, suggesting that Tbx5 functions very early in the pectoral fin induction pathway. Moderate reduction of Tbx5 by morpholino causes fin malformations, revealing an additional early requirement for Tbx5 in coordinating the axes of fin outgrowth. The heart of heartstrings mutant embryos appears to form and function normally through the early heart tube stage, manifesting only a slight bradycardia compared with wild-type siblings. However, the heart fails to loop and then progressively deteriorates, a process affecting the ventricle as well as the atrium. Relative to mammals, fish require lower levels of Tbx5 to produce malformed appendages and display whole-heart rather than atrial-predominant cardiac defects. However, the syndromic deficiencies of tbx5 mutation are remarkably well retained between fish and mammals. PMID:12223419

  4. Mutations in FEZF1 cause Kallmann syndrome.

    PubMed

    Kotan, L Damla; Hutchins, B Ian; Ozkan, Yusuf; Demirel, Fatma; Stoner, Hudson; Cheng, Paul J; Esen, Ihsan; Gurbuz, Fatih; Bicakci, Y Kenan; Mengen, Eda; Yuksel, Bilgin; Wray, Susan; Topaloglu, A Kemal

    2014-09-01

    Gonadotropin-releasing hormone (GnRH) neurons originate outside the CNS in the olfactory placode and migrate into the CNS, where they become integral components of the hypothalamic-pituitary-gonadal (HPG) axis. Disruption of this migration results in Kallmann syndrome (KS), which is characterized by anosmia and pubertal failure due to hypogonadotropic hypogonadism. Using candidate-gene screening, autozygosity mapping, and whole-exome sequencing in a cohort of 30 individuals with KS, we searched for genes newly associated with KS. We identified homozygous loss-of-function mutations in FEZF1 in two independent consanguineous families each with two affected siblings. The FEZF1 product is known to enable axons of olfactory receptor neurons (ORNs) to penetrate the CNS basal lamina in mice. Because a subset of axons in these tracks is the migratory pathway for GnRH neurons, in FEZF1 deficiency, GnRH neurons also fail to enter the brain. These results indicate that FEZF1 is required for establishment of the central component of the HPG axis in humans.

  5. Mutations in FEZF1 Cause Kallmann Syndrome

    PubMed Central

    Kotan, L. Damla; Hutchins, B. Ian; Ozkan, Yusuf; Demirel, Fatma; Stoner, Hudson; Cheng, Paul J.; Esen, Ihsan; Gurbuz, Fatih; Bicakci, Y. Kenan; Mengen, Eda; Yuksel, Bilgin; Wray, Susan; Topaloglu, A. Kemal

    2014-01-01

    Gonadotropin-releasing hormone (GnRH) neurons originate outside the CNS in the olfactory placode and migrate into the CNS, where they become integral components of the hypothalamic-pituitary-gonadal (HPG) axis. Disruption of this migration results in Kallmann syndrome (KS), which is characterized by anosmia and pubertal failure due to hypogonadotropic hypogonadism. Using candidate-gene screening, autozygosity mapping, and whole-exome sequencing in a cohort of 30 individuals with KS, we searched for genes newly associated with KS. We identified homozygous loss-of-function mutations in FEZF1 in two independent consanguineous families each with two affected siblings. The FEZF1 product is known to enable axons of olfactory receptor neurons (ORNs) to penetrate the CNS basal lamina in mice. Because a subset of axons in these tracks is the migratory pathway for GnRH neurons, in FEZF1 deficiency, GnRH neurons also fail to enter the brain. These results indicate that FEZF1 is required for establishment of the central component of the HPG axis in humans. PMID:25192046

  6. Milder progressive cerebellar atrophy caused by biallelic SEPSECS mutations.

    PubMed

    Iwama, Kazuhiro; Sasaki, Masayuki; Hirabayashi, Shinichi; Ohba, Chihiro; Iwabuchi, Emi; Miyatake, Satoko; Nakashima, Mitsuko; Miyake, Noriko; Ito, Shuichi; Saitsu, Hirotomo; Matsumoto, Naomichi

    2016-06-01

    Cerebellar atrophy is recognized in various types of childhood neurological disorders with clinical and genetic heterogeneity. Genetic analyses such as whole exome sequencing are useful for elucidating the genetic basis of these conditions. Pathological recessive mutations in Sep (O-phosphoserine) tRNA:Sec (selenocysteine) tRNA synthase (SEPSECS) have been reported in a total of 11 patients with pontocerebellar hypoplasia type 2, progressive cerebellocerebral atrophy or progressive encephalopathy, yet detailed clinical features are limited to only four patients. We identified two new families with progressive cerebellar atrophy, and by whole exome sequencing detected biallelic SEPSECS mutations: c.356A>G (p.Asn119Ser) and c.77delG (p.Arg26Profs*42) in family 1, and c.356A>G (p.Asn119Ser) and c.467G>A (p.Arg156Gln) in family 2. Their development was slightly delayed regardless of normal brain magnetic resonance imaging (MRI) in infancy. The progression of clinical symptoms in these families is evidently slower than in previously reported cases, and the cerebellar atrophy milder by brain MRI, indicating that SEPSECS mutations are also involved in milder late-onset cerebellar atrophy. PMID:26888482

  7. A mutation in arylsulfatase B gene causes mucopolysuccharidosis VI in rats

    SciTech Connect

    Kunieda, T.; Ikadai, H.; Desnick, R.J.

    1994-09-01

    Mucopolysuccharidosis (MPS) type VI comprises a group of autosomal recessive disorders caused by the deficiency of arylsulfatase B (ARSB) and subsequent lysosomal storage of glucosaminoglycans. We have identified a mutant rat strain that has remarkable similarites to human MPS VI. Recently, we have localized the autosomal recessive gene for the mutant phenotype on rat chromosome 2 by linkage analysis. The rat chromosome 2 is syntenic with the human and mouse chromosomes on which ARSB genes were assigned. Thus the mutant rats were expected to have a mutation in the ARSB gene. A normal rat liver cDNA library was screened using the cat ARSB cDNA as a probe, and clones which cover almost all of the complete ARSB open reading frame were isolated. The nucleotide sequence and amino acid sequence of the rat ARSB sequence showed 80% and 85% similarities with the human ARSB gene, respectively. The ARSB gene was assigned to rat chromosome 2 by using a rat-mouse hybrid cell panel, confirming the linkage analysis. Based on the nucleotide sequence of the normal rat ARSB gene, RT-PCR using liver RNA of the mutant rat was carried out to isolate the cDNA of the mutant rat ARSB gene. By sequencing several independent clones, the cDNA of the mutant rat was found to have a one base insertion at nucleotide 507, resulting in a frameshift mutation in the coding region of the rat ARSB gene, which introduces a stop codon in position 258 of the putative ARSB polypeptide. All affected MPS VI rats were homozygous for the mutant allele, while all phenotypically normal rats were heterozygous or homozygous for the wild type allele, indicating a perfect correspondence between the MPS VI phenotype and the genotype of the mutation. We conclude that the mutation in the ARSB gene is responsible for MPS VI in the rat, and that the mutant rat is an excellent model for study of human MPS VI pathogenesis and treatment.

  8. Congenital bovine spinal dysmyelination is caused by a missense mutation in the SPAST gene

    PubMed Central

    Nissen, Peter H.; Agerholm, Jørgen S.; Bendixen, Christian

    2009-01-01

    Bovine spinal dysmyelination (BSD) is a recessive congenital neurodegenerative disease in cattle (Bos taurus) characterized by pathological changes of the myelin sheaths in the spinal cord. The occurrence of BSD is a longstanding problem in the American Brown Swiss (ABS) breed and in several European cattle breeds upgraded with ABS. Here, we show that the disease locus on bovine chromosome 11 harbors the SPAST gene that, when mutated, is responsible for the human disorder hereditary spastic paraplegia (HSP). Initially, SPAST encoding Spastin was considered a less likely candidate gene for BSD since the modes of inheritance as well as the time of onset and severity of symptoms differ widely between HSP and BSD. However, sequence analysis of the bovine SPAST gene in affected animals identified a R560Q substitution at a position in the ATPase domain of the Spastin protein that is invariant from insects to mammals. Interestingly, three different mutations in human SPAST gene at the equivalent position are known to cause HSP. To explore this observation further, we genotyped more than 3,100 animals of various cattle breeds and found that the glutamine allele exclusively occurred in breeds upgraded with ABS. Furthermore, all confirmed BSD carriers were heterozygous, while all affected calves were homozygous for the glutamine allele consistent with recessive transmission of the underlying mutation and complete penetrance in the homozygous state. Subsequent analysis of recombinant Spastin in vitro showed that the R560Q substitution severely impaired the ATPase activity, demonstrating a causal relationship between the SPAST mutation and BSD. PMID:19714378

  9. [Effects of monorecessive and double recessive mutations affecting coat color on the monoamine content of the brain of the American mink (Mustela vison Schreber, 1777)].

    PubMed

    Trapezov, O V; Trapezova, L I; alekhina, T A; Klochkov, D V; Ivanov, Iu N

    2009-12-01

    The effects of mutations affecting the coat color on the dopamine, noradrenaline, and serotonin contents of the hypothalamus and brainstem of the American mink have been studied. The sample comprised standard (+/+) and mutant minks, including the monorecessive pastel (b/b), silver-blue (p/p), and white hedlund (h/h) and the combination double recessive sapphire (a/a p/p) and pearl (k/k p/p) ones. The dopamine content of the brainstem of the monorecessive pastel (b/b) and silver-blue (p/p) minks has been found to be higher than in standard (+/+) minks. Conversely, the homozigosity for two coat color loci in double recessive pearl minks (k/k p/p) significantly decreases the noradrenaline and serotonin contents of the hypothalamus. In addition, monorecessive and double recessive minks differ from each other in the serotonin contents of the midbrain and medulla.

  10. A novel L218P mutation in NADH-cytochrome b5 reductase associated with type I recessive congenital methemoglobinemia.

    PubMed

    Arikoglu, Tugba; Yarali, Nese; Kara, Abdurrahman; Bay, Ali; Bozkaya, Ikbal O; Tunc, Bahattin; Percy, Melanie J

    2009-01-01

    The presence of central cyanosis that is unrelated to cardiopulmonary causes alerts clinicians to a possible diagnosis of methemoglobinemia. Congenital methemoglobinemia due to deficiency of nicotinamide-adenine dinucleotide (NADH)-cytochrome b5 reductase (cb(5)r) is an autosomal recessive disorder characterized by life long cyanosis. Here we report a six-year old boy who presented with central cyanosis and upon examination revealed a methemoglobin level of 19.0%. Sequencing the CYB5R3 gene identified a homozygous T-->C transition at base c.653, which changed codon 218 from leucine to proline (L218P) in cb(5)r protein. Treatment with ascorbic acid relieved the cyanosis and returned methemoglobin levels to normal. PMID:19579085

  11. Sternopleural is a regulatory mutation of wingless with both dominant and recessive effects on larval development of Drosophila melanogaster

    SciTech Connect

    Neumann, C.J.; Cohen, S.M.

    1996-04-01

    The Drosophila wingless (wg) gene encodes a secreted signaling protein that is required for many separate patterning events in both embryonic and larval development. wg functions in the development of the adult structures have been studied using the conditional mutant wg{sup ts} and also using regulatory mutations of wg that reduce larval functions. Here we present evidence that Sternopleural (Sp) is another regulatory allele of wg that affects a subset of larval functions. Sp has both a recessive loss-of-function component and a gain-of-function component. The loss-of-function component reflects a reduction of wg activity in the notum and in the antenna. The gain-of-function component apparently leads to ectopic wg activity in the dorsal first and second leg disc and thereby generates the dominant Sp phenotype. Sp and other wg alleles show a complex pattern of complementation. We present evidence that these genetic properties are due to transvection. These results have implications for the genetic definition of a null allele at loci subject to transvection. 31 refs., 6 figs., 1 tab.

  12. Congenital central hypothyroidism due to a homozygous mutation in the thyrotropin beta-subunit gene follows an autosomal recessive inheritance.

    PubMed

    Doeker, B M; Pfäffle, R W; Pohlenz, J; Andler, W

    1998-05-01

    A 5-month-old infant of nonconsanguineous parents had severe hypothyroidism. Undetectable serum levels of T3 and T4 in combination with an undetectable baseline TSH level led to the diagnosis of central hypothyroidism. Administration of TRH failed to increase serum TSH, but not PRL, confirming isolated TSH deficiency. Measurement of the TSH in serum with three different immunoassays that recognize different epitopes of the TSH molecule failed to detect TSH, suggesting an aberrant or absent TSH. Direct sequencing of the entire coding region of the human TSH beta-subunit gene revealed a homozygous single base pair deletion in codon 105, resulting in a frame shift with a premature stop at codon 114. The truncated TSH beta peptide lacks the terminal five amino acids. Furthermore, the cysteine in codon 105 that is believed to be important for the interaction of the TSH beta-subunit with the alpha-subunit, is replaced with a valine (C105V), supporting the theory of a conformational change in the TSH molecule. Genotyping confirmed that the proposita was homozygous for this mutation, whereas her unaffected parents, the paternal grand-mother, and the maternal grandfather were heterozygous. Thus, isolated TSH deficiency follows an autosomal recessive mode of inheritance in this kindred.

  13. Overlapping DSPP mutations cause dentin dysplasia and dentinogenesis imperfecta.

    PubMed

    McKnight, D A; Simmer, J P; Hart, P S; Hart, T C; Fisher, L W

    2008-12-01

    Dentinogenesis imperfecta (DGI) and dentin dysplasia (DD) are allelic disorders due to mutations in DSPP. Typically, the phenotype breeds true within a family. Recently, two reports showed that 3 different net -1 bp frameshift mutations early in DSPP's repeat domain caused DD, whereas 6 more 3' frameshift mutations were associated with DGI. Here we identify a DD kindred with a novel -1 bp frameshift (c.3141delC) that falls within the portion of the DSPP repeat domain previously associated solely with the DGI phenotype. This new frameshift mutation shows that overlapping DSPP mutations can give rise to either DGI or DD phenotypes. Furthermore, the consistent kindred presentation of the DD or DGI phenotype appears to be dependent on an as-yet-undescribed genetic modifier closely linked to DSPP.

  14. Novel mutations in EVC cause aberrant splicing in Ellis-van Creveld syndrome.

    PubMed

    Shi, Lisong; Luo, Chunyan; Ahmed, Mairaj K; Attaie, Ali B; Ye, Xiaoqian

    2016-04-01

    Ellis-van Creveld syndrome (EvC) is a rare autosomal recessive disorder characterized by disproportionate chondrodysplasia, postaxial polydactyly, nail dystrophy, dental abnormalities and in a proportion of patients, congenital cardiac malformations. Weyers acrofacial dysostosis (Weyers) is another dominantly inherited disorder allelic to EvC syndrome but with milder phenotypes. Both disorders can result from loss-of-function mutations in either EVC or EVC2 gene, and phenotypes associated with the two gene mutations are clinically indistinguishable. We present here a clinical and molecular analysis of a Chinese family manifested specific features of EvC syndrome. Sequencing of both EVC and EVC2 identified two novel heterozygous splice site mutations c.384+5G>C in intron 3 and c.1465-1G>A in intron 10 in EVC, which were inherited from mother and father, respectively. In vitro minigene expression assay, RT-PCR and sequencing analysis demonstrated that c.384+5G>C mutation abolished normal splice site and created a new cryptic acceptor site within exon 4, whereas c.1465-1G>A mutation affected consensus splice junction site and resulted in full exon 11 skipping. These two aberrant pre-mRNA splicing processes both produced in-frame abnormal transcripts that possibly led to abolishment of important functional domains. To our knowledge, this is the first report of EVC mutations that cause EvC syndrome in Chinese population. Our data revealed that EVC splice site mutations altered splicing pattern and helped elucidate the pathogenesis of EvC syndrome. PMID:26621368

  15. Novel mutations in EVC cause aberrant splicing in Ellis-van Creveld syndrome.

    PubMed

    Shi, Lisong; Luo, Chunyan; Ahmed, Mairaj K; Attaie, Ali B; Ye, Xiaoqian

    2016-04-01

    Ellis-van Creveld syndrome (EvC) is a rare autosomal recessive disorder characterized by disproportionate chondrodysplasia, postaxial polydactyly, nail dystrophy, dental abnormalities and in a proportion of patients, congenital cardiac malformations. Weyers acrofacial dysostosis (Weyers) is another dominantly inherited disorder allelic to EvC syndrome but with milder phenotypes. Both disorders can result from loss-of-function mutations in either EVC or EVC2 gene, and phenotypes associated with the two gene mutations are clinically indistinguishable. We present here a clinical and molecular analysis of a Chinese family manifested specific features of EvC syndrome. Sequencing of both EVC and EVC2 identified two novel heterozygous splice site mutations c.384+5G>C in intron 3 and c.1465-1G>A in intron 10 in EVC, which were inherited from mother and father, respectively. In vitro minigene expression assay, RT-PCR and sequencing analysis demonstrated that c.384+5G>C mutation abolished normal splice site and created a new cryptic acceptor site within exon 4, whereas c.1465-1G>A mutation affected consensus splice junction site and resulted in full exon 11 skipping. These two aberrant pre-mRNA splicing processes both produced in-frame abnormal transcripts that possibly led to abolishment of important functional domains. To our knowledge, this is the first report of EVC mutations that cause EvC syndrome in Chinese population. Our data revealed that EVC splice site mutations altered splicing pattern and helped elucidate the pathogenesis of EvC syndrome.

  16. A novel splice site mutation of CDHR1 in a consanguineous Israeli Christian Arab family segregating autosomal recessive cone-rod dystrophy

    PubMed Central

    Cohen, Ben; Chervinsky, Elena; Jabaly-Habib, Haneen; Shalev, Stavit A.; Briscoe, Daniel

    2012-01-01

    Purpose To investigate the genetic basis for autosomal recessive cone-rod dystrophy in a consanguineous Israeli Christian Arab family. Methods Patients underwent a detailed ophthalmic examination, including funduscopy, electroretinography (ERG), visual field testing, and optical coherence tomography. Genome-wide homozygosity mapping using a single nucleotide polymorphism array was performed to identify homozygous regions shared between the two affected individuals. Mutation screening of the underlying gene was performed with direct sequencing. In silico analysis was used to predict the effect of the mutation on splicing. Results The family included two affected individuals. Clinical findings included progressive deterioration of visual acuity, photophobia, defective color vision, loss of central visual fields, pigmentary deposits localized mainly in the peripheral retina, a thinned and atrophic macular region, retinal vessel attenuation, absent ERG cone responses, and reduced ERG rod responses. Homozygosity mapping revealed several homozygous intervals shared among the affected individuals. One, a 12Mb interval on chromosome 10, included the CDHR1 gene. Direct sequencing revealed a single base transversion, c.1485+2T>G, located in the conserved donor splice site of Intron 13. This mutation cosegregated with the disease in the family, and was not detected in 208 Israeli Christian Arab control chromosomes. In silico analysis predicted that this mutation eliminates the Intron 13 donor splice site. Conclusions Only three distinct pathogenic mutations of CDHR1 have been reported to date in patients with autosomal recessive retinal degeneration. Here we report a novel splice site mutation of CDHR1, c.1485+2T>G, underlying autosomal recessive cone-rod dystrophy in a consanguineous Israeli Christian Arab family. This report expands the spectrum of pathogenic mutations of the CDHR1 gene. PMID:23233793

  17. An ENU-Induced Mutation of Cdh23 Causes Congenital Hearing Loss, but No Vestibular Dysfunction, in Mice

    PubMed Central

    Manji, Shehnaaz S.M.; Miller, Kerry A.; Williams, Louise H.; Andreasen, Lotte; Siboe, Maria; Rose, Elizabeth; Bahlo, Melanie; Kuiper, Michael; Dahl, Hans-Henrik M.

    2011-01-01

    Mutations in the human cadherin 23 (CDH23) gene cause deafness, neurosensory, autosomal recessive 12 (DFNB12) nonsyndromic hearing loss or Usher syndrome, type 1D (characterized by hearing impairment, vestibular dysfunction, and visual impairment). Reported waltzer mouse strains each harbor a Cdh23-null mutation and present with hearing loss and vestibular dysfunction. Two additional Cdh23 mouse mutants, salsa and erlong, each carry a homozygous Cdh23 missense mutation and have progressive hearing loss. We report the identification of a novel mouse strain, jera, with inherited hearing loss caused by an N-ethyl-N-nitrosourea–induced c.7079T>A mutation in the Cdh23 gene. The mutation generates a missense change, p.V2360E, in Cdh23. Affected mice have profound sensorineural deafness, with no vestibular dysfunction. The p.V2360E mutation is semidominant because heterozygous mice have milder and more progressive hearing loss in advanced age. The mutation affects a highly conserved Ca2+-binding motif in extracellular domain 22, thought to be important for Cdh23 structure and dimerization. Molecular modeling suggests that the Cdh23V2360E/V2360E mutation alters the structural conformation of the protein and affects Ca2+-binding properties. Similar to salsa mice, but in contrast to waltzer mice, hair bundle development is normal in jera and hearing loss appears to be due to the loss of tip links. Thus, jera is a novel mouse model for DFNB12. PMID:21689626

  18. 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

  19. 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

  20. Mutations in Either TUBB or MAPRE2 Cause Circumferential Skin Creases Kunze Type.

    PubMed

    Isrie, Mala; Breuss, Martin; Tian, Guoling; Hansen, Andi Harley; Cristofoli, Francesca; Morandell, Jasmin; Kupchinsky, Zachari A; Sifrim, Alejandro; Rodriguez-Rodriguez, Celia Maria; Dapena, Elena Porta; Doonanco, Kurston; Leonard, Norma; Tinsa, Faten; Moortgat, Stéphanie; Ulucan, Hakan; Koparir, Erkan; Karaca, Ender; Katsanis, Nicholas; Marton, Valeria; Vermeesch, Joris Robert; Davis, Erica E; Cowan, Nicholas J; Keays, David Anthony; Van Esch, Hilde

    2015-12-01

    Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect. PMID:26637975

  1. Adult-onset painful axonal polyneuropathy caused by a dominant NAGLU mutation

    PubMed Central

    Tétreault, Martine; Gonzalez, Michael; Dicaire, Marie-Josée; Allard, Pierre; Gehring, Kalle; Leblanc, Diane; Leclerc, Nadine; Schondorf, Ronald; Mathieu, Jean; Zuchner, Stephan

    2015-01-01

    Late-onset painful sensory neuropathies are usually acquired conditions associated with common diseases. Adult presentations of known hereditary forms are often accompanied by other organ involvement. We recruited a large French-Canadian family with a dominantly inherited late-onset painful sensory neuropathy. The main clinical feature is recurrent leg pain that progresses to constant painful paraesthesias in the feet and later the hands. As it evolves, some patients develop a mild sensory ataxia. We selected four affected individuals for whole exome sequencing. Analysis of rare variants shared by all cases led to a list of four candidate variants. Segregation analysis in all 45 recruited individuals has shown that only the p.Ile403Thr variant in the α-N-acetyl-glucosaminidase (NAGLU) gene segregates with the disease. Recessive NAGLU mutations cause the severe childhood lysosomal disease mucopolysacharidosis IIIB. Family members carrying the mutation showed a significant decrease of the enzymatic function (average 45%). The late-onset and variable severity of the symptoms may have precluded the description of such symptoms in parents of mucopolysaccharidosis IIIB cases. The identification of a dominant phenotype associated with a NAGLU mutation supports that some carriers of lysosomal enzyme mutations may develop later in life much milder phenotypes. PMID:25818867

  2. Mutations in Either TUBB or MAPRE2 Cause Circumferential Skin Creases Kunze Type.

    PubMed

    Isrie, Mala; Breuss, Martin; Tian, Guoling; Hansen, Andi Harley; Cristofoli, Francesca; Morandell, Jasmin; Kupchinsky, Zachari A; Sifrim, Alejandro; Rodriguez-Rodriguez, Celia Maria; Dapena, Elena Porta; Doonanco, Kurston; Leonard, Norma; Tinsa, Faten; Moortgat, Stéphanie; Ulucan, Hakan; Koparir, Erkan; Karaca, Ender; Katsanis, Nicholas; Marton, Valeria; Vermeesch, Joris Robert; Davis, Erica E; Cowan, Nicholas J; Keays, David Anthony; Van Esch, Hilde

    2015-12-01

    Circumferential skin creases Kunze type (CSC-KT) is a specific congenital entity with an unknown genetic cause. The disease phenotype comprises characteristic circumferential skin creases accompanied by intellectual disability, a cleft palate, short stature, and dysmorphic features. Here, we report that mutations in either MAPRE2 or TUBB underlie the genetic origin of this syndrome. MAPRE2 encodes a member of the microtubule end-binding family of proteins that bind to the guanosine triphosphate cap at growing microtubule plus ends, and TUBB encodes a β-tubulin isotype that is expressed abundantly in the developing brain. Functional analyses of the TUBB mutants show multiple defects in the chaperone-dependent tubulin heterodimer folding and assembly pathway that leads to a compromised yield of native heterodimers. The TUBB mutations also have an impact on microtubule dynamics. For MAPRE2, we show that the mutations result in enhanced MAPRE2 binding to microtubules, implying an increased dwell time at microtubule plus ends. Further, in vivo analysis of MAPRE2 mutations in a zebrafish model of craniofacial development shows that the variants most likely perturb the patterning of branchial arches, either through excessive activity (under a recessive paradigm) or through haploinsufficiency (dominant de novo paradigm). Taken together, our data add CSC-KT to the growing list of tubulinopathies and highlight how multiple inheritance paradigms can affect dosage-sensitive biological systems so as to result in the same clinical defect.

  3. A novel mutation in the AGXT gene causing primary hyperoxaluria type I: genotype-phenotype correlation.

    PubMed

    M'Dimegh, Saoussen; Aquaviva-Bourdain, Cécile; Omezzine, Asma; M'Barek, Ibtihel; Souche, Geneviéve; Zellama, Dorsaf; Abidi, Kamel; Achour, Abdelattif; Gargah, Tahar; Abroug, Saoussen; Bouslama, Ali

    2016-09-01

    Primary hyperoxaluria type I (PH1) is an autosomal recessive metabolic disorder caused by inherited mutations in the AGXT gene encoding liver peroxisomal alanine : glyoxylate aminotransferase (AGT) which is deficient or mistargeted to mitochondria. PH1 shows considerable phenotypic and genotypic heterogeneity. The incidence and severity of PH1 varies in different geographic regions. DNA samples of the affected members from two unrelated Tunisian families were tested by amplifying and sequencing each of the AGXT exons and intron-exon junctions. We identified a novel frameshift mutation in the AGXT gene, the c.406_410dupACTGC resulting in a truncated protein (p.Gln137Hisfs*19). It is found in homozygous state in two nonconsanguineous unrelated families from Tunisia. These molecular findings provide genotype/phenotype correlations in the intrafamilial phenotypic and permit accurate carrier detection, and prenatal diagnosis. The novel p.Gln137Hisfs*19 mutation detected in our study extend the spectrum of known AGXT gene mutations in Tunisia. PMID:27659337

  4. [Mutations in the gene encoding filaggrin cause ichthyosis vulgaris].

    PubMed

    Prasad, Sumangali Chandra; Rasmussen, Kirsten; Bygum, Anette

    2011-02-14

    Ichthyosis vulgaris is a common genetic skin disorder with an estimated prevalence of 1:250 caused by mutations in the gene encoding filaggrin. This disorder manifests itself within the first year of life and is clinically characterized by dry, scaly skin, keratosis pilaris, palmar hyperlinearity and atopic manifestations. Patients with a severe phenotype are homozygous or compound heterozygous for the mutations, whereas heterozygous patients show mild disease, suggesting semidominant inheritance with incomplete penetrance. We present a patient with classic severe ichthyosis vulgaris, atopic eczema and two loss-of-function mutations.

  5. A novel PITX2 mutation causing iris hypoplasia

    PubMed Central

    Kimura, Masashi; Tokita, Yoshihito; Machida, Junichiro; Shibata, Akio; Tatematsu, Tadashi; Tsurusaki, Yoshinori; Miyake, Noriko; Saitsu, Hirotomo; Miyachi, Hitoshi; Shimozato, Kazuo; Matsumoto, Naomichi; Nakashima, Mitsuko

    2014-01-01

    Iris hypoplasia (IH) is rare autosomal dominant disorder characterized by a poorly developed iris stroma and malformations of the eyes and umbilicus. This disorder is caused by mutation of the paired-like homeodomain 2 (PITX2) gene. Here, we describe a novel PITX2 mutation (c.205C>T) in an IH family presenting with very mild eye features but with tooth agenesis as the most obvious clinical feature. PMID:27081499

  6. The existence of species rests on a metastable equilibrium between inbreeding and outbreeding. An essay on the close relationship between speciation, inbreeding and recessive mutations

    PubMed Central

    2011-01-01

    Background Speciation corresponds to the progressive establishment of reproductive barriers between groups of individuals derived from an ancestral stock. Since Darwin did not believe that reproductive barriers could be selected for, he proposed that most events of speciation would occur through a process of separation and divergence, and this point of view is still shared by most evolutionary biologists today. Results I do, however, contend that, if so much speciation occurs, the most likely explanation is that there must be conditions where reproductive barriers can be directly selected for. In other words, situations where it is advantageous for individuals to reproduce preferentially within a small group and reduce their breeding with the rest of the ancestral population. This leads me to propose a model whereby new species arise not by populations splitting into separate branches, but by small inbreeding groups "budding" from an ancestral stock. This would be driven by several advantages of inbreeding, and mainly by advantageous recessive phenotypes, which could only be retained in the context of inbreeding. Reproductive barriers would thus not arise as secondary consequences of divergent evolution in populations isolated from one another, but under the direct selective pressure of ancestral stocks. Many documented cases of speciation in natural populations appear to fit the model proposed, with more speciation occurring in populations with high inbreeding coefficients, and many recessive characters identified as central to the phenomenon of speciation, with these recessive mutations expected to be surrounded by patterns of limited genomic diversity. Conclusions Whilst adaptive evolution would correspond to gains of function that would, most of the time, be dominant, this type of speciation by budding would thus be driven by mutations resulting in the advantageous loss of certain functions since recessive mutations very often correspond to the inactivation of

  7. Mutations in the ABCC6 gene as a cause of generalized arterial calcification of infancy: genotypic overlap with pseudoxanthoma elasticum.

    PubMed

    Li, Qiaoli; Brodsky, Jill L; Conlin, Laura K; Pawel, Bruce; Glatz, Andrew C; Gafni, Rachel I; Schurgers, Leon; Uitto, Jouni; Hakonarson, Hakon; Deardorff, Matthew A; Levine, Michael A

    2014-03-01

    Generalized arterial calcification of infancy (GACI) is an autosomal recessive disorder characterized by congenital calcification of large- and medium-sized arteries, associated with early myocardial infarction, heart failure, and stroke, and premature death. Most cases of GACI are caused by mutations in the ENPP1 gene. We first studied two siblings with GACI from a non-consanguineous family without mutations in the ENPP1 gene. To search for disease-causing mutations, we identified genomic regions shared between the two affected siblings but not their unaffected parents or brother. The ABCC6 gene, which is mutated in pseudoxanthoma elasticum (PXE), resided within a small region of homozygosity shared by the affected siblings. Sequence analysis of ABCC6 revealed that the two affected siblings were homozygous for the missense mutation p.R1314W. Subsequently, ABCC6 mutations were identified in five additional GACI families with normal ENPP1 sequences. Genetic mutations in ABCC6 in patients with PXE are associated with ectopic tissue mineralization in the skin and arterial blood vessels. Thus, our findings provide additional evidence that the ABCC6 gene product inhibits calcification under physiologic conditions and confirm a second locus for GACI. In addition, our study emphasizes the potential utility of shared homozygosity mapping to identify genetic causes of inherited disorders.

  8. 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.

  9. 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

  10. Screening of DFNB3 in Iranian families with autosomal recessive non-syndromic hearing loss reveals a novel pathogenic mutation in the MyTh4 domain of the MYO15A gene in a linked family

    PubMed Central

    Reiisi, Somayeh; Tabatabaiefar, Mohammad Amin; Sanati, Mohammad Hosein; Chaleshtori, Morteza Hashemzadeh

    2016-01-01

    Objective(s): Non-syndromic sensorineural hearing loss (NSHL) is a common disorder affecting approximately 1 in 500 newborns. This type of hearing loss is extremely heterogeneous and includes over 100 loci. Mutations in the GJB2 gene have been implicated in about half of autosomal recessive non-syndromic hearing loss (ARNSHL) cases, making this the most common cause of ARNSHL. For the latter form of deafness, most frequent genes proposed include GJB2, SLC26A4, MYO15A, OTOF, and CDH23 worldwide. Materials and Methods: The aim of the present study was to define the role and frequency of MYO15A gene mutation in Iranian families. In this study 30 Iranian families were enrolled with over three deaf children and negative for GJB2. Then linkage analysis was performed by six DFNB3 short tandem repeat markers. Following that, mutation detection accomplished using DNA sequencing. Results: One family (3.33%) showed linkage to DFNB3 and a novel mutation was identified in the MYO15A gene (c.6442T>A): as the disease-causing mutation. Mutation co-segregated with hearing loss in the family but was not present in the 100 ethnicity-matched controls. Conclusion: Our results confirmed that the hearing loss of the linked Iranian family was caused by a novel missense mutation in the MYO15A gene. This mutation is the first to be reported in the world and affects the first MyTH4 domain of the protein. PMID:27635202

  11. Smith-Lemli-Opitz syndrome is caused by mutations in the 7-dehydrocholesterol reductase gene.

    PubMed Central

    Waterham, H R; Wijburg, F A; Hennekam, R C; Vreken, P; Poll-The, B T; Dorland, L; Duran, M; Jira, P E; Smeitink, J A; Wevers, R A; Wanders, R J

    1998-01-01

    Smith-Lemli-Opitz syndrome is a frequently occurring autosomal recessive developmental disorder characterized by facial dysmorphisms, mental retardation, and multiple congenital anomalies. Biochemically, the disorder is caused by deficient activity of 7-dehydrocholesterol reductase, which catalyzes the final step in the cholesterol-biosynthesis pathway-that is, the reduction of the Delta7 double bond of 7-dehydrocholesterol to produce cholesterol. We identified a partial transcript coding for human 7-dehydrocholesterol reductase by searching the database of expressed sequence tags with the amino acid sequence for the Arabidopsis thaliana sterol Delta7-reductase and isolated the remaining 5' sequence by the "rapid amplification of cDNA ends" method, or 5'-RACE. The cDNA has an open reading frame of 1,425 bp coding for a polypeptide of 475 amino acids with a calculated molecular weight of 54.5 kD. Heterologous expression of the cDNA in the yeast Saccharomyces cerevisiae confirmed that it codes for 7-dehydrocholesterol reductase. Chromosomal mapping experiments localized the gene to chromosome 11q13. Sequence analysis of fibroblast 7-dehydrocholesterol reductase cDNA from three patients with Smith-Lemli-Opitz syndrome revealed distinct mutations, including a 134-bp insertion and three different point mutations, each of which was heterozygous in cDNA from the respective parents. Our data demonstrate that Smith-Lemli-Opitz syndrome is caused by mutations in the gene coding for 7-dehydrocholesterol reductase. PMID:9683613

  12. Screening for SH3TC2 gene mutations in a series of demyelinating recessive Charcot-Marie-Tooth disease (CMT4).

    PubMed

    Piscosquito, Giuseppe; Saveri, Paola; Magri, Stefania; Ciano, Claudia; Gandioli, Claudia; Morbin, Michela; Bella, Daniela D; Moroni, Isabella; Taroni, Franco; Pareyson, Davide

    2016-09-01

    Charcot-Marie-Tooth disease type 4C (CMT4C) is an autosomal recessive (AR) demyelinating neuropathy associated to SH3TC2 mutations, characterized by early onset, spine deformities, and cranial nerve involvement. We screened 43 CMT4 patients (36 index cases) with AR inheritance, demyelinating nerve conductions, and negative testing for PMP22 duplication, GJB1 and MPZ mutations, for SH3TC2 mutations. Twelve patients (11 index cases) had CMT4C as they carried homozygous or compound heterozygous mutations in SH3TC2. We found six mutations: three nonsense (p.R1109*, p.R954*, p.Q892*), one splice site (c.805+2T>C), one synonymous variant (p.K93K) predicting altered splicing, and one frameshift (p.F491Lfs*32) mutation. The splice site and the frameshift mutations are novel. Mean onset age was 7 years (range: 1-14). Neuropathy was moderate-to-severe. Scoliosis was present in 11 patients (severe in 4), and cranial nerve deficits in 9 (hearing loss in 7). Scoliosis and cranial nerve involvement are frequent features of this CMT4 subtype, and their presence should prompt the clinician to look for SH3TC2 gene mutations. In our series of undiagnosed CMT4 patients, SH3TC2 mutation frequency is 30%, confirming that CMT4C may be the most common AR-CMT type.

  13. A DSPP mutation causing dentinogenesis imperfecta and characterization of the mutational effect.

    PubMed

    Lee, Sook-Kyung; Lee, Kyung-Eun; Song, Su Jeong; Hyun, Hong-Keun; Lee, Sang-Hoon; Kim, Jung-Wook

    2013-01-01

    Mutations in the DSPP gene have been identified in nonsyndromic hereditary dentin defects, but the genotype-phenotype correlations are not fully understood. Recently, it has been demonstrated that the mutations of DSPP affecting the IPV leader sequence result in mutant DSPP retention in rough endoplasmic reticulum (ER). In this study, we identified a Korean family with dentinogenesis imperfecta type III. To identify the disease causing mutation in this family, we performed mutational analysis based on candidate gene sequencing. Exons and exon-intron boundaries of DSPP gene were sequenced, and the effects of the identified mutation on the pre-mRNA splicing and protein secretion were investigated. Candidate gene sequencing revealed a mutation (c.50C > T, p.P17L) in exon 2 of the DSPP gene. The splicing assay showed that the mutation did not influence pre-mRNA splicing. However, the mutation interfered with protein secretion and resulted in the mutant protein remaining largely in the ER. These results suggest that the mutation affects ER-to-Golgi apparatus export and results in the reduction of secreted DSPP and ER overload. This may induce cell stress and damage processing and/or transport of dentin matrix proteins or other critical proteins.

  14. Novel GABRG2 mutations cause familial febrile seizures

    PubMed Central

    Boillot, Morgane; Morin-Brureau, Mélanie; Picard, Fabienne; Weckhuysen, Sarah; Lambrecq, Virginie; Minetti, Carlo; Striano, Pasquale; Zara, Federico; Iacomino, Michele; Ishida, Saeko; An-Gourfinkel, Isabelle; Daniau, Mailys; Hardies, Katia; Baulac, Michel; Dulac, Olivier; Leguern, Eric; Nabbout, Rima

    2015-01-01

    Objective: To identify the genetic cause in a large family with febrile seizures (FS) and temporal lobe epilepsy (TLE) and subsequently search for additional mutations in a cohort of 107 families with FS, with or without epilepsy. Methods: The cohort consisted of 1 large family with FS and TLE, 64 smaller French families recruited through a national French campaign, and 43 Italian families. Molecular analyses consisted of whole-exome sequencing and mutational screening. Results: Exome sequencing revealed a p.Glu402fs*3 mutation in the γ2 subunit of the GABAA receptor gene (GABRG2) in the large family with FS and TLE. Three additional nonsense and frameshift GABRG2 mutations (p.Arg136*, p.Val462fs*33, and p.Pro59fs*12), 1 missense mutation (p.Met199Val), and 1 exonic deletion were subsequently identified in 5 families of the follow-up cohort. Conclusions: We report GABRG2 mutations in 5.6% (6/108) of families with FS, with or without associated epilepsy. This study provides evidence that GABRG2 mutations are linked to the FS phenotype, rather than epilepsy, and that loss-of-function of GABAA receptor γ2 subunit is the probable underlying pathogenic mechanism. PMID:27066572

  15. 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

  16. A novel homozygous LMNA mutation (p.Met540Ile) causes mandibuloacral dysplasia type A.

    PubMed

    Yassaee, Vahid Reza; Khojaste, Arash; Hashemi-Gorji, Feyzollah; Ravesh, Zeinab; Toosi, Parviz

    2016-02-10

    Mandibuloacral dysplasia with type A lipodystrophy (MADA) is a rare genetic disorder inherited in an autosomal recessive fashion characterized by hypoplasia of the mandible and clavicles, acroosteolysis and lipodystrophy due to mutations in the LMNA or ZMPSTE24 genes. In the current study, we have investigated a consanguineous family clinically diagnosed with mandibuloacral dysplasia type A having an affected child for the LMNA gene alteration(s). Mother is now 15weeks pregnant, seeking advice on the health of her fetus. Peripheral blood was obtained from all family members after informed consent was achieved. Genomic DNA was isolated. The sequence of the LMNA gene, including all exons and intron boundaries was analyzed by PCR and Sanger sequencing. Chorionic villus was collected from the placenta to reveal the condition of the fetus. Molecular analysis ascertained a homozygous mutation c.1620G>A (p.M540I) in the proband and heterozygous alteration in the family. Genomic DNA isolated from the CVS was amplified using specific primers for identified deleterious mutation and analyzed by Sanger sequencing. Two pathogenic mutations c.1620G>A and c.1698C>T were identified in the fetus. Genetic counseling as well as justified rapid and sensitive genetic testing can provide reassurance for the families to prevent the high burden of genetic disorders. We have also applied several online tools including PolyPhen2, MUpro, SIFT, PoPMuSiC, Project HOPE and Mutation Taster to predict the impact of p.Met540Ile substitution as a hotspot region within LMNA. All tools showed reduction in the stability of the protein structure. We conclude that p.M540I mutation may causes disease in the homozygous state. PMID:26602028

  17. Mutations in GMPPB cause congenital myasthenic syndrome and bridge myasthenic disorders with dystroglycanopathies.

    PubMed

    Belaya, Katsiaryna; Rodríguez Cruz, Pedro M; Liu, Wei Wei; Maxwell, Susan; McGowan, Simon; Farrugia, Maria E; Petty, Richard; Walls, Timothy J; Sedghi, Maryam; Basiri, Keivan; Yue, Wyatt W; Sarkozy, Anna; Bertoli, Marta; Pitt, Matthew; Kennett, Robin; Schaefer, Andrew; Bushby, Kate; Parton, Matt; Lochmüller, Hanns; Palace, Jacqueline; Muntoni, Francesco; Beeson, David

    2015-09-01

    Congenital myasthenic syndromes are inherited disorders that arise from impaired signal transmission at the neuromuscular junction. Mutations in at least 20 genes are known to lead to the onset of these conditions. Four of these, ALG2, ALG14, DPAGT1 and GFPT1, are involved in glycosylation. Here we identify a fifth glycosylation gene, GMPPB, where mutations cause congenital myasthenic syndrome. First, we identified recessive mutations in seven cases from five kinships defined as congenital myasthenic syndrome using decrement of compound muscle action potentials on repetitive nerve stimulation on electromyography. The mutations were present through the length of the GMPPB, and segregation, in silico analysis, exon trapping, cell transfection followed by western blots and immunostaining were used to determine pathogenicity. GMPPB congenital myasthenic syndrome cases show clinical features characteristic of congenital myasthenic syndrome subtypes that are due to defective glycosylation, with variable weakness of proximal limb muscle groups while facial and eye muscles are largely spared. However, patients with GMPPB congenital myasthenic syndrome had more prominent myopathic features that were detectable on muscle biopsies, electromyography, muscle magnetic resonance imaging, and through elevated serum creatine kinase levels. Mutations in GMPPB have recently been reported to lead to the onset of muscular dystrophy dystroglycanopathy. Analysis of four additional GMPPB-associated muscular dystrophy dystroglycanopathy cases by electromyography found that a defective neuromuscular junction component is not always present. Thus, we find mutations in GMPPB can lead to a wide spectrum of clinical features where deficit in neuromuscular transmission is the major component in a subset of cases. Clinical recognition of GMPPB-associated congenital myasthenic syndrome may be complicated by the presence of myopathic features, but correct diagnosis is important because affected

  18. Mutations in GMPPB cause congenital myasthenic syndrome and bridge myasthenic disorders with dystroglycanopathies

    PubMed Central

    Belaya, Katsiaryna; Rodríguez Cruz, Pedro M.; Liu, Wei Wei; Maxwell, Susan; McGowan, Simon; Farrugia, Maria E.; Petty, Richard; Walls, Timothy J.; Sedghi, Maryam; Basiri, Keivan; Yue, Wyatt W.; Sarkozy, Anna; Bertoli, Marta; Pitt, Matthew; Kennett, Robin; Schaefer, Andrew; Bushby, Kate; Parton, Matt; Lochmüller, Hanns; Palace, Jacqueline; Muntoni, Francesco

    2015-01-01

    Congenital myasthenic syndromes are inherited disorders that arise from impaired signal transmission at the neuromuscular junction. Mutations in at least 20 genes are known to lead to the onset of these conditions. Four of these, ALG2, ALG14, DPAGT1 and GFPT1, are involved in glycosylation. Here we identify a fifth glycosylation gene, GMPPB, where mutations cause congenital myasthenic syndrome. First, we identified recessive mutations in seven cases from five kinships defined as congenital myasthenic syndrome using decrement of compound muscle action potentials on repetitive nerve stimulation on electromyography. The mutations were present through the length of the GMPPB, and segregation, in silico analysis, exon trapping, cell transfection followed by western blots and immunostaining were used to determine pathogenicity. GMPPB congenital myasthenic syndrome cases show clinical features characteristic of congenital myasthenic syndrome subtypes that are due to defective glycosylation, with variable weakness of proximal limb muscle groups while facial and eye muscles are largely spared. However, patients with GMPPB congenital myasthenic syndrome had more prominent myopathic features that were detectable on muscle biopsies, electromyography, muscle magnetic resonance imaging, and through elevated serum creatine kinase levels. Mutations in GMPPB have recently been reported to lead to the onset of muscular dystrophy dystroglycanopathy. Analysis of four additional GMPPB-associated muscular dystrophy dystroglycanopathy cases by electromyography found that a defective neuromuscular junction component is not always present. Thus, we find mutations in GMPPB can lead to a wide spectrum of clinical features where deficit in neuromuscular transmission is the major component in a subset of cases. Clinical recognition of GMPPB-associated congenital myasthenic syndrome may be complicated by the presence of myopathic features, but correct diagnosis is important because affected

  19. Homozygous mutation of STXBP5L explains an autosomal recessive infantile-onset neurodegenerative disorder.

    PubMed

    Kumar, Raman; Corbett, Mark A; Smith, Nicholas J C; Jolly, Lachlan A; Tan, Chuan; Keating, Damien J; Duffield, Michael D; Utsumi, Toshihiko; Moriya, Koko; Smith, Katherine R; Hoischen, Alexander; Abbott, Kim; Harbord, Michael G; Compton, Alison G; Woenig, Joshua A; Arts, Peer; Kwint, Michael; Wieskamp, Nienke; Gijsen, Sabine; Veltman, Joris A; Bahlo, Melanie; Gleeson, Joseph G; Haan, Eric; Gecz, Jozef

    2015-04-01

    We report siblings of consanguineous parents with an infantile-onset neurodegenerative disorder manifesting a predominant sensorimotor axonal neuropathy, optic atrophy and cognitive deficit. We used homozygosity mapping to identify an ∼12-Mbp interval identical by descent (IBD) between the affected individuals on chromosome 3q13.13-21.1 with an LOD score of 2.31. We combined family-based whole-exome and whole-genome sequencing of parents and affected siblings and, after filtering of likely non-pathogenic variants, identified a unique missense variant in syntaxin-binding protein 5-like (STXBP5L c.3127G>A, p.Val1043Ile [CCDS43137.1]) in the IBD interval. Considering other modes of inheritance, we also found compound heterozygous variants in FMNL3 (c.114G>C, p.Phe38Leu and c.1372T>G, p.Ile458Leu [CCDS44874.1]) located on chromosome 12. STXBP5L (or Tomosyn-2) is expressed in the central and peripheral nervous system and is known to inhibit neurotransmitter release through inhibition of the formation of the SNARE complexes between synaptic vesicles and the plasma membrane. FMNL3 is expressed more widely and is a formin family protein that is involved in the regulation of cell morphology and cytoskeletal organization. The STXBP5L p.Val1043Ile variant enhanced inhibition of exocytosis in comparison with wild-type (WT) STXBP5L. Furthermore, WT STXBP5L, but not variant STXBP5L, promoted axonal outgrowth in manipulated mouse primary hippocampal neurons. However, the FMNL3 p.Phe38Leu and p.Ile458Leu variants showed minimal effects in these cells. Collectively, our clinical, genetic and molecular data suggest that the IBD variant in STXBP5L is the likely cause of the disorder.

  20. Functional consequences of transferrin receptor-2 mutations causing hereditary hemochromatosis type 3

    PubMed Central

    Joshi, Ricky; Shvartsman, Maya; Morán, Erica; Lois, Sergi; Aranda, Jessica; Barqué, Anna; de la Cruz, Xavier; Bruguera, Miquel; Vagace, José Manuel; Gervasini, Guillermo; Sanz, Cristina; Sánchez, Mayka

    2015-01-01

    Hereditary hemochromatosis (HH) type 3 is an autosomal recessive disorder of iron metabolism characterized by excessive iron deposition in the liver and caused by mutations in the transferrin receptor 2 (TFR2) gene. Here, we describe three new HH type 3 Spanish families with four TFR2 mutations (p.Gly792Arg, c.1606-8A>G, Gln306*, and Gln672*). The missense variation p.Gly792Arg was found in homozygosity in two adult patients of the same family, and in compound heterozygosity in an adult proband that also carries a novel intronic change (c.1606-8A>G). Two new nonsense TFR2 mutations (Gln306* and Gln672*) were detected in a pediatric case. We examine the functional consequences of two TFR2 variants (p.Gly792Arg and c.1606-8A>G) using molecular and computational methods. Cellular protein localization studies using immunofluorescence demonstrated that the plasma membrane localization of p.Gly792Arg TFR2 is impaired. Splicing studies in vitro and in vivo reveal that the c.1606-8A>G mutation leads to the creation of a new acceptor splice site and an aberrant TFR2 mRNA. The reported mutations caused HH type 3 by protein truncation, altering TFR2 membrane localization or by mRNA splicing defect, producing a nonfunctional TFR2 protein and a defective signaling transduction for hepcidin regulation. TFR2 genotyping should be considered in adult but also in pediatric cases with early-onset of iron overload. PMID:26029709

  1. Mutations in the pre-replication complex cause Meier-Gorlin syndrome.

    PubMed

    Bicknell, Louise S; Bongers, Ernie M H F; Leitch, Andrea; Brown, Stephen; Schoots, Jeroen; Harley, Margaret E; Aftimos, Salim; Al-Aama, Jumana Y; Bober, Michael; Brown, Paul A J; van Bokhoven, Hans; Dean, John; Edrees, Alaa Y; Feingold, Murray; Fryer, Alan; Hoefsloot, Lies H; Kau, Nikolaus; Knoers, Nine V A M; Mackenzie, James; Opitz, John M; Sarda, Pierre; Ross, Alison; Temple, I Karen; Toutain, Annick; Wise, Carol A; Wright, Michael; Jackson, Andrew P

    2011-04-01

    Meier-Gorlin syndrome (ear, patella and short-stature syndrome) is an autosomal recessive primordial dwarfism syndrome characterized by absent or hypoplastic patellae and markedly small ears¹⁻³. Both pre- and post-natal growth are impaired in this disorder, and although microcephaly is often evident, intellect is usually normal in this syndrome. We report here that individuals with this disorder show marked locus heterogeneity, and we identify mutations in five separate genes: ORC1, ORC4, ORC6, CDT1 and CDC6. All of these genes encode components of the pre-replication complex, implicating defects in replication licensing as the cause of a genetic syndrome with distinct developmental abnormalities. PMID:21358632

  2. Mutations in PCYT1A cause spondylometaphyseal dysplasia with cone-rod dystrophy.

    PubMed

    Yamamoto, Guilherme L; Baratela, Wagner A R; Almeida, Tatiana F; Lazar, Monize; Afonso, Clara L; Oyamada, Maria K; Suzuki, Lisa; Oliveira, Luiz A N; Ramos, Ester S; Kim, Chong A; Passos-Bueno, Maria Rita; Bertola, Débora R

    2014-01-01

    Spondylometaphyseal dysplasia with cone-rod dystrophy is a rare autosomal-recessive disorder characterized by severe short stature, progressive lower-limb bowing, flattened vertebral bodies, metaphyseal involvement, and visual impairment caused by cone-rod dystrophy. Whole-exome sequencing of four individuals affected by this disorder from two Brazilian families identified two previously unreported homozygous mutations in PCYT1A. This gene encodes the alpha isoform of the phosphate cytidylyltransferase 1 choline enzyme, which is responsible for converting phosphocholine into cytidine diphosphate-choline, a key intermediate step in the phosphatidylcholine biosynthesis pathway. A different enzymatic defect in this pathway has been previously associated with a muscular dystrophy with mitochondrial structural abnormalities that does not have cartilage and/or bone or retinal involvement. Thus, the deregulation of the phosphatidylcholine pathway may play a role in multiple genetic diseases in humans, and further studies are necessary to uncover its precise pathogenic mechanisms and the entirety of its phenotypic spectrum.

  3. Alexander disease: a leukodystrophy caused by a mutation in GFAP.

    PubMed

    Johnson, Anne B

    2004-05-01

    Alexander disease, a rare fatal disorder of the central nervous system, causes progressive loss of motor and mental function. Until recently it was of unknown etiology, almost all cases were sporadic, and there was no effective treatment. It was most common in an infantile form, somewhat less so in a juvenile form, and was rarely seen in an adult-onset form. A number of investigators have now shown that almost all cases of Alexander disease have a dominant mutation in one allele of the gene for glial fibrillary acidic protein (GFAP) that causes replacement of one amino acid for another. Only in very rare cases of the adult-onset form is the mutation present in either parent. Thus, in almost all cases, the mutation arises as a spontaneous event, possibly in the germ cell of one parent.

  4. Mutations in LPIN1 cause recurrent acute myoglobinuria in childhood.

    PubMed

    Zeharia, Avraham; Shaag, Avraham; Houtkooper, Riekelt H; Hindi, Tareq; de Lonlay, Pascale; Erez, Gilli; Hubert, Laurence; Saada, Ann; de Keyzer, Yves; Eshel, Gideon; Vaz, Frédéric M; Pines, Ophry; Elpeleg, Orly

    2008-10-01

    Recurrent episodes of life-threatening myoglobinuria in childhood are caused by inborn errors of glycogenolysis, mitochondrial fatty acid beta-oxidation, and oxidative phosphorylation. Nonetheless, approximately half of the patients do not suffer from a defect in any of these pathways. Using homozygosity mapping, we identified six deleterious mutations in the LPIN1 gene in patients who presented at 2-7 years of age with recurrent, massive rhabdomyolysis. The LPIN1 gene encodes the muscle-specific phosphatidic acid phosphatase, a key enzyme in triglyceride and membrane phospholipid biosynthesis. Of six individuals who developed statin-induced myopathy, one was a carrier for Glu769Gly, a pathogenic mutation in the LPIN1 gene. Analysis of phospholipid content disclosed accumulation of phosphatidic acid and lysophospholipids in muscle tissue of the more severe genotype. Mutations in the LPIN1 gene cause recurrent rhabdomyolysis in childhood, and a carrier state may predispose for statin-induced myopathy. PMID:18817903

  5. Mutations in LPIN1 cause recurrent acute myoglobinuria in childhood.

    PubMed

    Zeharia, Avraham; Shaag, Avraham; Houtkooper, Riekelt H; Hindi, Tareq; de Lonlay, Pascale; Erez, Gilli; Hubert, Laurence; Saada, Ann; de Keyzer, Yves; Eshel, Gideon; Vaz, Frédéric M; Pines, Ophry; Elpeleg, Orly

    2008-10-01

    Recurrent episodes of life-threatening myoglobinuria in childhood are caused by inborn errors of glycogenolysis, mitochondrial fatty acid beta-oxidation, and oxidative phosphorylation. Nonetheless, approximately half of the patients do not suffer from a defect in any of these pathways. Using homozygosity mapping, we identified six deleterious mutations in the LPIN1 gene in patients who presented at 2-7 years of age with recurrent, massive rhabdomyolysis. The LPIN1 gene encodes the muscle-specific phosphatidic acid phosphatase, a key enzyme in triglyceride and membrane phospholipid biosynthesis. Of six individuals who developed statin-induced myopathy, one was a carrier for Glu769Gly, a pathogenic mutation in the LPIN1 gene. Analysis of phospholipid content disclosed accumulation of phosphatidic acid and lysophospholipids in muscle tissue of the more severe genotype. Mutations in the LPIN1 gene cause recurrent rhabdomyolysis in childhood, and a carrier state may predispose for statin-induced myopathy.

  6. Autosomal Recessive Bestrophinopathy Is Not Associated With the Loss of Bestrophin-1 Anion Channel Function in a Patient With a Novel BEST1 Mutation

    PubMed Central

    Johnson, Adiv A.; Bachman, Lori A.; Gilles, Benjamin J.; Cross, Samuel D.; Stelzig, Kimberly E.; Resch, Zachary T.; Marmorstein, Lihua Y.; Pulido, Jose S.; Marmorstein, Alan D.

    2015-01-01

    Purpose Mutations in BEST1, encoding bestrophin-1 (Best1), cause autosomal recessive bestrophinopathy (ARB). Encoding bestrophin-1 is a pentameric anion channel localized to the basolateral plasma membrane of the RPE. Here, we characterize the effects of the mutations R141H (CGC > CAC) and I366fsX18 (c.1098_1100+7del), identified in a patient in our practice, on Best1 trafficking, oligomerization, and channel activity. Methods Currents of Cl− were assessed in transfected HEK293 cells using whole-cell patch clamp. Best1 localization was assessed by confocal microscopy in differentiated, human-induced pluripotent stem cell-derived RPE (iPSC-RPE) cells following expression of mutants via adenovirus-mediated gene transfer. Oligomerization was evaluated by coimmunoprecipitation in iPSC-RPE and MDCK cells. Results Compared to Best1, Best1I366fsX18 currents were increased while Best1R141H Cl− currents were diminished. Coexpression of Best1R141H with Best1 or Best1I366fsX18 resulted in rescued channel activity. Overexpressed Best1, Best1R141H, and Best1I366fsX18 were all properly localized in iPSC-RPE cells; Best1R141H and Best1I366fsX18 coimmunoprecipitated with endogenous Best1 in iPSC-RPE cells and with each other in MDCK cells. Conclusions The first 366 amino acids of Best1 are sufficient to mediate channel activity and homo-oligomerization. The combination of Best1 and Best1R141H does not cause disease, while Best1R141H together with Best1I366fsX18 causes ARB. Since both combinations generate comparable Cl− currents, this indicates that ARB in this patient is not caused by a loss of channel activity. Moreover, Best1I366fsX18 differs from Best1 in that it lacks most of the cytosolic C-terminal domain, suggesting that the loss of this region contributes significantly to the pathogenesis of ARB in this patient. PMID:26200502

  7. Mutations in CSPP1 Cause Primary Cilia Abnormalities and Joubert Syndrome with or without Jeune Asphyxiating Thoracic Dystrophy

    PubMed Central

    Tuz, Karina; Bachmann-Gagescu, Ruxandra; O’Day, Diana R.; Hua, Kiet; Isabella, Christine R.; Phelps, Ian G.; Stolarski, Allan E.; O’Roak, Brian J.; Dempsey, Jennifer C.; Lourenco, Charles; Alswaid, Abdulrahman; Bönnemann, Carsten G.; Medne, Livija; Nampoothiri, Sheela; Stark, Zornitza; Leventer, Richard J.; Topçu, Meral; Cansu, Ali; Jagadeesh, Sujatha; Done, Stephen; Ishak, Gisele E.; Glass, Ian A.; Shendure, Jay; Neuhauss, Stephan C.F.; Haldeman-Englert, Chad R.; Doherty, Dan; Ferland, Russell J.

    2014-01-01

    Joubert syndrome (JBTS) is a recessive ciliopathy in which a subset of affected individuals also have the skeletal dysplasia Jeune asphyxiating thoracic dystrophy (JATD). Here, we have identified biallelic truncating CSPP1 (centrosome and spindle pole associated protein 1) mutations in 19 JBTS-affected individuals, four of whom also have features of JATD. CSPP1 mutations explain ∼5% of JBTS in our cohort, and despite truncating mutations in all affected individuals, the range of phenotypic severity is broad. Morpholino knockdown of cspp1 in zebrafish caused phenotypes reported in other zebrafish models of JBTS (curved body shape, pronephric cysts, and cerebellar abnormalities) and reduced ciliary localization of Arl13b, further supporting loss of CSPP1 function as a cause of JBTS. Fibroblasts from affected individuals with CSPP1 mutations showed reduced numbers of primary cilia and/or short primary cilia, as well as reduced axonemal localization of ciliary proteins ARL13B and adenylyl cyclase III. In summary, CSPP1 mutations are a major cause of the Joubert-Jeune phenotype in humans; however, the mechanism by which these mutations lead to both JBTS and JATD remains unknown. PMID:24360808

  8. A Novel Splice-Site Mutation in the GJB2 Gene Causing Mild Postlingual Hearing Impairment

    PubMed Central

    Gandía, Marta; del Castillo, Francisco J.; Rodríguez-Álvarez, Francisco J.; Garrido, Gema; Villamar, Manuela; Calderón, Manuela; Moreno-Pelayo, Miguel A.; Moreno, Felipe; del Castillo, Ignacio

    2013-01-01

    The DFNB1 subtype of autosomal recessive, nonsyndromic hearing impairment, caused by mutations affecting the GJB2 (connection-26) gene, is highly prevalent in most populations worldwide. DFNB1 hearing impairment is mostly severe or profound and usually appears before the acquisition of speech (prelingual onset), though a small number of hypomorphic missense mutations result in mild or moderate deafness of postlingual onset. We identified a novel GJB2 splice-site mutation, c. -22-2A>C, in three siblings with mild postlingual hearing impairment that were compound heterozygous for c. -22-2A>C and c.35delG. Reverse transcriptase-PCR experiments performed on total RNA extracted from saliva samples from one of these siblings confirmed that c. -22-2A>C abolished the acceptor splice site of the single GJB2 intron, resulting in the absence of normally processed transcripts from this allele. However, we did isolate transcripts from the c. -22-2A>C allele that keep an intact GJB2 coding region and that were generated by use of an alternative acceptor splice site previously unknown. The residual expression of wild-type connection-26 encoded by these transcripts probably underlies the mild severity and late onset of the hearing impairment of these subjects. PMID:24039984

  9. DCDC2 Mutations Cause a Renal-Hepatic Ciliopathy by Disrupting Wnt Signaling

    PubMed Central

    Schueler, Markus; Braun, Daniela A.; Chandrasekar, Gayathri; Gee, Heon Yung; Klasson, Timothy D.; Halbritter, Jan; Bieder, Andrea; Porath, Jonathan D.; Airik, Rannar; Zhou, Weibin; LoTurco, Joseph J.; Che, Alicia; Otto, Edgar A.; Böckenhauer, Detlef; Sebire, Neil J.; Honzik, Tomas; Harris, Peter C.; Koon, Sarah J.; Gunay-Aygun, Meral; Saunier, Sophie; Zerres, Klaus; Bruechle, Nadina Ortiz; Drenth, Joost P.H.; Pelletier, Laurence; Tapia-Páez, Isabel; Lifton, Richard P.; Giles, Rachel H.; Kere, Juha; Hildebrandt, Friedhelm

    2015-01-01

    Nephronophthisis-related ciliopathies (NPHP-RC) are recessive diseases characterized by renal dysplasia or degeneration. We here identify mutations of DCDC2 as causing a renal-hepatic ciliopathy. DCDC2 localizes to the ciliary axoneme and to mitotic spindle fibers in a cell-cycle-dependent manner. Knockdown of Dcdc2 in IMCD3 cells disrupts ciliogenesis, which is rescued by wild-type (WT) human DCDC2, but not by constructs that reflect human mutations. We show that DCDC2 interacts with DVL and DCDC2 overexpression inhibits β-catenin-dependent Wnt signaling in an effect additive to Wnt inhibitors. Mutations detected in human NPHP-RC lack these effects. A Wnt inhibitor likewise restores ciliogenesis in 3D IMCD3 cultures, emphasizing the importance of Wnt signaling for renal tubulogenesis. Knockdown of dcdc2 in zebrafish recapitulates NPHP-RC phenotypes, including renal cysts and hydrocephalus, which is rescued by a Wnt inhibitor and by WT, but not by mutant, DCDC2. We thus demonstrate a central role of Wnt signaling in the pathogenesis of NPHP-RC, suggesting an avenue for potential treatment of NPHP-RC. PMID:25557784

  10. A CHRNE frameshift mutation causes congenital myasthenic syndrome in young Jack Russell Terriers.

    PubMed

    Rinz, Caitlin J; Lennon, Vanda A; James, Fiona; Thoreson, James B; Tsai, Kate L; Starr-Moss, Alison N; Humphries, H Dale; Guo, Ling T; Palmer, Anthony C; Clark, Leigh Anne; Shelton, G Diane

    2015-12-01

    Congenital myasthenic syndromes (CMSs) are a group of rare genetic disorders of the neuromuscular junction resulting in structural or functional causes of fatigable weakness that usually begins early in life. Mutations in pre-synaptic, synaptic and post-synaptic proteins have been demonstrated in human cases, with more than half involving aberrations in nicotinic acetylcholine receptor (AChR) subunits. CMS was first recognized in dogs in 1974 as an autosomal recessive trait in Jack Russell Terriers (JRTs). A deficiency of junctional AChRs was demonstrated. Here we characterize a CMS in 2 contemporary cases of JRT littermates with classic clinical and electromyographic findings, and immunochemical confirmation of an approximately 90% reduction in AChR protein content. Loci encoding the 5 AChR subunits were evaluated using microsatellite markers, and CHRNB1 and CHRNE were identified as candidate genes. Sequences of the splice sites and exons of both genes revealed a single base insertion in exon 7 of CHRNE that predicts a frameshift mutation and a premature stop codon. We further demonstrated this pathogenic mutation in CHRNE in archival tissues from unrelated JRTs studied 34 years ago.

  11. Mutations in DYNC2LI1 disrupt cilia function and cause short rib polydactyly syndrome

    PubMed Central

    Taylor, S. Paige; Dantas, Tiago J.; Duran, Ivan; Wu, Sulin; Lachman, Ralph S.; Nelson, Stanley F.; Cohn, Daniel H.; Vallee, Richard B.; Krakow, Deborah

    2015-01-01

    The short rib polydactyly syndromes (SRPS) are a heterogeneous group of autosomal recessive, perinatal-lethal skeletal disorders characterized primarily by short, horizontal ribs, short limbs, and poly-dactyly. Mutations in several genes affecting intraflagellar transport (IFT) cause SRPS but they do not account for all cases. Here we identify additional SRPS genes and further unravel the functional basis for IFT. We perform whole exome sequencing and identify mutations in a new disease-producing gene, cytoplasmic dynein-2 light intermediate chain 1, DYNC2LI1, segregating with disease in three families. Using primary fibroblasts, we show that DYNC2LI1 is essential for dynein-2 complex stability and that mutations in DYNC2LI1 result in variable-length, including hyperelongated, cilia, Hedgehog pathway impairment, and ciliary IFT accumulations. The findings in this study expand our understanding of SRPS locus heterogeneity and demonstrate the importance of DYNC2LI1 in dynein-2 complex stability, cilium function, Hedgehog regulation, and skeletogenesis. PMID:26077881

  12. Mutations in TAX1BP3 cause dilated cardiomyopathy with septo-optic dysplasia.

    PubMed

    Reinstein, Eyal; Orvin, Katia; Tayeb-Fligelman, Einav; Stiebel-Kalish, Hadas; Tzur, Shay; Pimienta, Allen L; Bazak, Lily; Bengal, Tuvia; Cohen, Lior; Gaton, Dan D; Bormans, Concetta; Landau, Meytal; Kornowski, Ran; Shohat, Mordechai; Behar, Doron M

    2015-04-01

    We describe a Bedouin family with a novel autosomal recessive syndrome characterized by dilated cardiomyopathy and septo-optic dysplasia. Genetic analysis revealed a homozygous missense mutation in TAX1BP3, which encodes a small PDZ domain containing protein implicated in regulation of the Wnt/β-catenin signaling pathway, as the causative mutation. The mutation affects a conserved residue located at the core of TAX1BP3 binding pocket and is predicted to impair the nature of a crucial hydrophobic patch, thereby interrupting the structure and stability of the protein, and its ability to interact with other proteins. TAX1BP3 is highly expressed in heart and brain and consistent with the clinical findings observed in our patients; a knockdown of TAX1BP3 causes elongation defects, enlarged pericard, and enlarged head structures in zebrafish embryos. Thus, we describe a new genetic disorder that expands the monogenic cardiomyopathy disease spectrum and suggests that TAX1BP3 is essential for heart and brain development.

  13. A CHRNE frameshift mutation causes congenital myasthenic syndrome in young Jack Russell Terriers.

    PubMed

    Rinz, Caitlin J; Lennon, Vanda A; James, Fiona; Thoreson, James B; Tsai, Kate L; Starr-Moss, Alison N; Humphries, H Dale; Guo, Ling T; Palmer, Anthony C; Clark, Leigh Anne; Shelton, G Diane

    2015-12-01

    Congenital myasthenic syndromes (CMSs) are a group of rare genetic disorders of the neuromuscular junction resulting in structural or functional causes of fatigable weakness that usually begins early in life. Mutations in pre-synaptic, synaptic and post-synaptic proteins have been demonstrated in human cases, with more than half involving aberrations in nicotinic acetylcholine receptor (AChR) subunits. CMS was first recognized in dogs in 1974 as an autosomal recessive trait in Jack Russell Terriers (JRTs). A deficiency of junctional AChRs was demonstrated. Here we characterize a CMS in 2 contemporary cases of JRT littermates with classic clinical and electromyographic findings, and immunochemical confirmation of an approximately 90% reduction in AChR protein content. Loci encoding the 5 AChR subunits were evaluated using microsatellite markers, and CHRNB1 and CHRNE were identified as candidate genes. Sequences of the splice sites and exons of both genes revealed a single base insertion in exon 7 of CHRNE that predicts a frameshift mutation and a premature stop codon. We further demonstrated this pathogenic mutation in CHRNE in archival tissues from unrelated JRTs studied 34 years ago. PMID:26429099

  14. ANO10 mutations cause ataxia and coenzyme Q₁₀ deficiency.

    PubMed

    Balreira, Andrea; Boczonadi, Veronika; Barca, Emanuele; Pyle, Angela; Bansagi, Boglarka; Appleton, Marie; Graham, Claire; Hargreaves, Iain P; Rasic, Vedrana Milic; Lochmüller, Hanns; Griffin, Helen; Taylor, Robert W; Naini, Ali; Chinnery, Patrick F; Hirano, Michio; Quinzii, Catarina M; Horvath, Rita

    2014-11-01

    Inherited ataxias are heterogeneous disorders affecting both children and adults, with over 40 different causative genes, making molecular genetic diagnosis challenging. Although recent advances in next-generation sequencing have significantly improved mutation detection, few treatments exist for patients with inherited ataxia. In two patients with adult-onset cerebellar ataxia and coenzyme Q10 (CoQ10) deficiency in muscle, whole exome sequencing revealed mutations in ANO10, which encodes anoctamin 10, a member of a family of putative calcium-activated chloride channels, and the causative gene for autosomal recessive spinocerebellar ataxia-10 (SCAR10). Both patients presented with slowly progressive ataxia and dysarthria leading to severe disability in the sixth decade. Epilepsy and learning difficulties were also present in one patient, while retinal degeneration and cataract were present in the other. The detection of mutations in ANO10 in our patients indicate that ANO10 defects cause secondary low CoQ10 and SCAR10 patients may benefit from CoQ10 supplementation.

  15. Further evidence of POP1 mutations as the cause of anauxetic dysplasia.

    PubMed

    Elalaoui, Siham Chafai; Laarabi, Fatima Zahra; Mansouri, Maria; Mrani, Nidal Alaoui; Nishimura, Gen; Sefiani, Abdelaziz

    2016-09-01

    Anauxetic dysplasia (AAD, OMIM 607095) is a rare skeletal dysplasia inherited as an autosomal recessive trait, which is caused by mutations in RMRP and allelic to a more common disorder, cartilage hair hypoplasia (CHH). CHH is a multi-system disorder with a variety of extraskeletal changes. Whereas AAD is a bone-restricted disorder with a more severe skeletal phenotype: affected individuals are extremely short and complicated by orthopedic morbidity, and the radiological changes include modification of the vertebral bodies and epiphyseal dysplasia of the hip, as well as generalized metaphyseal dysplasia and severe brachydactyly. Recently, genetic heterogeneity for AAD was proposed, because a familial case (two affected sibs) with an AAD-identical phenotype had compound heterozygous mutations in POP1, encoding a molecule functionally related to the gene product of RMRP. We report here a 5-year-old boy with the same phenotype born to a consanguineous couple. We identified a novel homozygous POP1 mutation (c.1744C>T, p.P582S) in the boy and the heterozygosity in the parents. It may be rational to coin the POP1-associated skeletal phenotype AAD type 2. © 2016 Wiley Periodicals, Inc. PMID:27380734

  16. A deleterious mutation in SAMD9 causes normophosphatemic familial tumoral calcinosis.

    PubMed

    Topaz, Orit; Indelman, Margarita; Chefetz, Ilana; Geiger, Dan; Metzker, Aryeh; Altschuler, Yoram; Choder, Mordechai; Bercovich, Dani; Uitto, Jouni; Bergman, Reuven; Richard, Gabriele; Sprecher, Eli

    2006-10-01

    Familial tumoral calcinosis (FTC) is a rare autosomal recessive disorder characterized by the progressive deposition of calcified masses in cutaneous and subcutaneous tissues, which results in painful ulcerative lesions and severe skin and bone infections. Two major types of FTC have been recognized: hyperphosphatemic FTC (HFTC) and normophosphatemic FTC (NFTC). HFTC was recently shown to result from mutations in two different genes: GALNT3, which codes for a glycosyltransferase, and FGF23, which codes for a potent phosphaturic protein. To determine the molecular cause of NFTC, we performed homozygosity mapping in five affected families of Jewish Yemenite origin and mapped NFTC to 7q21-7q21.3. Mutation analysis revealed a homozygous mutation in the SAMD9 gene (K1495E), which was found to segregate with the disease in all families and to interfere with the protein expression. Our data suggest that SAMD9 is involved in the regulation of extraosseous calcification, a process of considerable importance in a wide range of diseases as common as atherosclerosis and autoimmune disorders.

  17. Does unemployment cause long-term mortality? Selection and causation after the 1992–96 deep Swedish recession

    PubMed Central

    Garcy, Anthony M.

    2016-01-01

    Background: Mass unemployment in Europe is endemic, especially among the young. Does it cause mortality? Methods: We analyzed long-term effects of unemployment occurring during the deep Swedish recession 1992–96. Mortality from all and selected causes was examined in the 6-year period after the recession among those employed in 1990 (3.4 million). Direct health selection was analyzed as risk of unemployment by prior medical history based on all hospitalizations 1981–91. Unemployment effects on mortality were estimated with and without adjustment for prior social characteristics and for prior medical history. Results: A prior circulatory disease history did not predict unemployment; a history of alcohol-related disease or suicide attempts did, in men and women. Unemployment predicted excess male, but not female, mortality from circulatory disease, both ischemic heart disease and stroke, and from all causes combined, after full adjustment. Adjustment for prior social characteristics reduced estimates considerably; additional adjustment for prior medical history did not. Mortality from external and alcohol-related causes was raised in men and women experiencing unemployment, after adjustment for social characteristics and medical history. For the youngest birth cohorts fully adjusted alcohol mortality HRs were substantial (male HR = 4.44; female HR = 5.73). The effect of unemployment on mortality was not uniform across the population; men, those with a low education, low income, unmarried or in urban employment were more vulnerable. Conclusions: Direct selection by medical history explains a modest fraction of any increased mortality risk following unemployment. Mass unemployment imposes long-term mortality risk on a sizeable segment of the population. PMID:27085193

  18. Mutations in the NHEJ component XRCC4 cause primordial dwarfism.

    PubMed

    Murray, Jennie E; van der Burg, Mirjam; IJspeert, Hanna; Carroll, Paula; Wu, Qian; Ochi, Takashi; Leitch, Andrea; Miller, Edward S; Kysela, Boris; Jawad, Alireza; Bottani, Armand; Brancati, Francesco; Cappa, Marco; Cormier-Daire, Valerie; Deshpande, Charu; Faqeih, Eissa A; Graham, Gail E; Ranza, Emmanuelle; Blundell, Tom L; Jackson, Andrew P; Stewart, Grant S; Bicknell, Louise S

    2015-03-01

    Non-homologous end joining (NHEJ) is a key cellular process ensuring genome integrity. Mutations in several components of the NHEJ pathway have been identified, often associated with severe combined immunodeficiency (SCID), consistent with the requirement for NHEJ during V(D)J recombination to ensure diversity of the adaptive immune system. In contrast, we have recently found that biallelic mutations in LIG4 are a common cause of microcephalic primordial dwarfism (MPD), a phenotype characterized by prenatal-onset extreme global growth failure. Here we provide definitive molecular genetic evidence supported by biochemical, cellular, and immunological data for mutations in XRCC4, encoding the obligate binding partner of LIG4, causing MPD. We report the identification of biallelic mutations in XRCC4 in five families. Biochemical and cellular studies demonstrate that these alterations substantially decrease XRCC4 protein levels leading to reduced cellular ligase IV activity. Consequently, NHEJ-dependent repair of ionizing-radiation-induced DNA double-strand breaks is compromised in XRCC4 cells. Similarly, immunoglobulin junctional diversification is impaired in cells. However, immunoglobulin levels are normal, and individuals lack overt signs of immunodeficiency. Additionally, in contrast to individuals with LIG4 mutations, pancytopenia leading to bone marrow failure has not been observed. Hence, alterations that alter different NHEJ proteins give rise to a phenotypic spectrum, from SCID to extreme growth failure, with deficiencies in certain key components of this repair pathway predominantly exhibiting growth deficits, reflecting differential developmental requirements for NHEJ proteins to support growth and immune maturation. PMID:25728776

  19. Mutations in the NHEJ Component XRCC4 Cause Primordial Dwarfism

    PubMed Central

    Murray, Jennie E.; van der Burg, Mirjam; IJspeert, Hanna; Carroll, Paula; Wu, Qian; Ochi, Takashi; Leitch, Andrea; Miller, Edward S.; Kysela, Boris; Jawad, Alireza; Bottani, Armand; Brancati, Francesco; Cappa, Marco; Cormier-Daire, Valerie; Deshpande, Charu; Faqeih, Eissa A.; Graham, Gail E.; Ranza, Emmanuelle; Blundell, Tom L.; Jackson, Andrew P.; Stewart, Grant S.; Bicknell, Louise S.

    2015-01-01

    Non-homologous end joining (NHEJ) is a key cellular process ensuring genome integrity. Mutations in several components of the NHEJ pathway have been identified, often associated with severe combined immunodeficiency (SCID), consistent with the requirement for NHEJ during V(D)J recombination to ensure diversity of the adaptive immune system. In contrast, we have recently found that biallelic mutations in LIG4 are a common cause of microcephalic primordial dwarfism (MPD), a phenotype characterized by prenatal-onset extreme global growth failure. Here we provide definitive molecular genetic evidence supported by biochemical, cellular, and immunological data for mutations in XRCC4, encoding the obligate binding partner of LIG4, causing MPD. We report the identification of biallelic mutations in XRCC4 in five families. Biochemical and cellular studies demonstrate that these alterations substantially decrease XRCC4 protein levels leading to reduced cellular ligase IV activity. Consequently, NHEJ-dependent repair of ionizing-radiation-induced DNA double-strand breaks is compromised in XRCC4 cells. Similarly, immunoglobulin junctional diversification is impaired in cells. However, immunoglobulin levels are normal, and individuals lack overt signs of immunodeficiency. Additionally, in contrast to individuals with LIG4 mutations, pancytopenia leading to bone marrow failure has not been observed. Hence, alterations that alter different NHEJ proteins give rise to a phenotypic spectrum, from SCID to extreme growth failure, with deficiencies in certain key components of this repair pathway predominantly exhibiting growth deficits, reflecting differential developmental requirements for NHEJ proteins to support growth and immune maturation. PMID:25728776

  20. ADCY5 mutations are another cause of benign hereditary chorea

    PubMed Central

    Mencacci, Niccolo E.; Wiethoff, Sarah; Hersheson, Joshua; Ryten, Mina; Balint, Bettina; Ganos, Christos; Stamelou, Maria; Quinn, Niall; Houlden, Henry; Wood, Nicholas W.; Bhatia, Kailash P.

    2015-01-01

    Objective: To determine the contribution of ADCY5 mutations in cases with genetically undefined benign hereditary chorea (BHC). Methods: We studied 18 unrelated cases with BHC (7 familial, 11 sporadic) who were negative for NKX2-1 mutations. The diagnosis of BHC was based on the presence of a childhood-onset movement disorder, predominantly characterized by chorea and no other major neurologic features. ADCY5 analysis was performed by whole-exome sequencing or Sanger sequencing. ADCY5 and NKX2-1 expression during brain development and in the adult human brain was assessed using microarray analysis of postmortem brain tissue. Results: The c.1252C>T; p.R418W mutation was identified in 2 cases (1 familial, 1 sporadic). The familial case inherited the mutation from the affected father, who had a much milder presentation, likely due to low-grade somatic mosaicism. The mutation was de novo in the sporadic case. The clinical presentation of these cases featured nonparoxysmal generalized chorea, as well as dystonia in the most severely affected, but no facial myokymia. We observed significant progression of symptoms in ADCY5 mutation carriers, in contrast to BHC secondary to NKX2-1 mutations. The difference in the clinical course is mirrored by the brain expression data, showing increasing ADCY5 expression in the striatum during brain development, whereas NKX2-1 shows an opposite trend. Conclusions: Our study identifies mutations in ADCY5, the gene previously linked to familial dyskinesia with facial myokymia, as a cause of familial and sporadic BHC. ADCY5 genetic analysis should be performed in cases with a benign choreiform movement disorder even in the absence of facial myokymia. PMID:26085604

  1. CCDC88A mutations cause PEHO-like syndrome in humans and mouse

    PubMed Central

    Nahorski, Michael S.; Asai, Masato; Wakeling, Emma; Parker, Alasdair; Asai, Naoya; Canham, Natalie; Holder, Susan E.; Chen, Ya-Chun; Dyer, Joshua

    2016-01-01

    Progressive encephalopathy with oedema, hypsarrhythmia and optic atrophy (PEHO) syndrome is a rare Mendelian phenotype comprising severe retardation, early onset epileptic seizures, optic nerve/cerebellar atrophy, pedal oedema, and early death. Atypical cases are often known as PEHO-like, and there is an overlap with ‘early infantile epileptic encephalopathy’. PEHO is considered to be recessive, but surprisingly since initial description in 1991, no causative recessive gene(s) have been described. Hence, we report a multiplex consanguineous family with the PEHO phenotype where affected individuals had a homozygous frame-shift deletion in CCDC88A (c.2313delT, p.Leu772*ter). Analysis of cDNA extracted from patient lymphocytes unexpectedly failed to show non-sense mediated decay, and we demonstrate that the mutation produces a truncated protein lacking the crucial C-terminal half of CCDC88A (girdin). To further investigate the possible role of CCDC88A in human neurodevelopment we re-examined the behaviour and neuroanatomy of Ccdc88a knockout pups. These mice had mesial-temporal lobe epilepsy, microcephaly and corpus callosum deficiency, and by postnatal Day 21, microcephaly; the mice died at an early age. As the mouse knockout phenotype mimics the human PEHO phenotype this suggests that loss of CCDC88A is a cause of the PEHO phenotype, and that CCDC88A is essential for multiple aspects of normal human neurodevelopment. PMID:26917597

  2. Mutation in Human Desmoplakin Domain Binding to Plakoglobin Causes a Dominant Form of Arrhythmogenic Right Ventricular Cardiomyopathy

    PubMed Central

    Rampazzo, Alessandra; Nava, Andrea; Malacrida, Sandro; Beffagna, Giorgia; Bauce, Barbara; Rossi, Valeria; Zimbello, Rosanna; Simionati, Barbara; Basso, Cristina; Thiene, Gaetano; Towbin, Jeffrey A.; Danieli, Gian A.

    2002-01-01

    Arrhythmogenic right ventricular cardiomyopathy (ARVD/C) is a genetically heterogeneous disease characterized by progressive degeneration of the right ventricular myocardium and increased risk of sudden death. Here, we report on a genome scan in one Italian family in which the disease appeared unlinked to any of the six different ARVD loci reported so far; we identify a mutation (S299R) in exon 7 of desmoplakin (DSP), which modifies a putative phosphorylation site in the N-terminal domain binding plakoglobin. It is interesting that a nonsense DSP mutation was reported elsewhere in the literature, inherited as a recessive trait and causing a biventricular dilative cardiomyopathy associated with palmoplantar keratoderma and woolly hairs. Therefore, different DSP mutations might produce different clinical phenotypes, with different modes of inheritance. PMID:12373648

  3. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism–dystonia

    PubMed Central

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E.; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y.; Simpson, Michael A.; Chong, W. K.; Jacques, Thomas S.; Woltjer, Randy L.; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M.; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R.; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A. M.; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S.; Yoganathan, Sangeetha; Dale, Russell C.; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A.; Enns, Caroline A.; Hayflick, Susan J.; Clayton, Peter T.; Mills, Philippa B.; Kurian, Manju A.; Wilson, Stephen W.

    2016-01-01

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism–dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142

  4. Mutations in SLC39A14 disrupt manganese homeostasis and cause childhood-onset parkinsonism-dystonia.

    PubMed

    Tuschl, Karin; Meyer, Esther; Valdivia, Leonardo E; Zhao, Ningning; Dadswell, Chris; Abdul-Sada, Alaa; Hung, Christina Y; Simpson, Michael A; Chong, W K; Jacques, Thomas S; Woltjer, Randy L; Eaton, Simon; Gregory, Allison; Sanford, Lynn; Kara, Eleanna; Houlden, Henry; Cuno, Stephan M; Prokisch, Holger; Valletta, Lorella; Tiranti, Valeria; Younis, Rasha; Maher, Eamonn R; Spencer, John; Straatman-Iwanowska, Ania; Gissen, Paul; Selim, Laila A M; Pintos-Morell, Guillem; Coroleu-Lletget, Wifredo; Mohammad, Shekeeb S; Yoganathan, Sangeetha; Dale, Russell C; Thomas, Maya; Rihel, Jason; Bodamer, Olaf A; Enns, Caroline A; Hayflick, Susan J; Clayton, Peter T; Mills, Philippa B; Kurian, Manju A; Wilson, Stephen W

    2016-01-01

    Although manganese is an essential trace metal, little is known about its transport and homeostatic regulation. Here we have identified a cohort of patients with a novel autosomal recessive manganese transporter defect caused by mutations in SLC39A14. Excessive accumulation of manganese in these patients results in rapidly progressive childhood-onset parkinsonism-dystonia with distinctive brain magnetic resonance imaging appearances and neurodegenerative features on post-mortem examination. We show that mutations in SLC39A14 impair manganese transport in vitro and lead to manganese dyshomeostasis and altered locomotor activity in zebrafish with CRISPR-induced slc39a14 null mutations. Chelation with disodium calcium edetate lowers blood manganese levels in patients and can lead to striking clinical improvement. Our results demonstrate that SLC39A14 functions as a pivotal manganese transporter in vertebrates. PMID:27231142

  5. DVL1 frameshift mutations clustering in the penultimate exon cause autosomal-dominant Robinow syndrome.

    PubMed

    White, Janson; Mazzeu, Juliana F; Hoischen, Alexander; Jhangiani, Shalini N; Gambin, Tomasz; Alcino, Michele Calijorne; Penney, Samantha; Saraiva, Jorge M; Hove, Hanne; Skovby, Flemming; Kayserili, Hülya; Estrella, Elicia; Vulto-van Silfhout, Anneke T; Steehouwer, Marloes; Muzny, Donna M; Sutton, V Reid; Gibbs, Richard A; Lupski, James R; Brunner, Han G; van Bon, Bregje W M; Carvalho, Claudia M B

    2015-04-01

    Robinow syndrome is a genetically heterogeneous disorder characterized by mesomelic limb shortening, genital hypoplasia, and distinctive facial features and for which both autosomal-recessive and autosomal-dominant inheritance patterns have been described. Causative variants in the non-canonical signaling gene WNT5A underlie a subset of autosomal-dominant Robinow syndrome (DRS) cases, but most individuals with DRS remain without a molecular diagnosis. We performed whole-exome sequencing in four unrelated DRS-affected individuals without coding mutations in WNT5A and found heterozygous DVL1 exon 14 mutations in three of them. Targeted Sanger sequencing in additional subjects with DRS uncovered DVL1 exon 14 mutations in five individuals, including a pair of monozygotic twins. In total, six distinct frameshift mutations were found in eight subjects, and all were heterozygous truncating variants within the penultimate exon of DVL1. In five families in which samples from unaffected parents were available, the variants were demonstrated to represent de novo mutations. All variant alleles are predicted to result in a premature termination codon within the last exon, escape nonsense-mediated decay (NMD), and most likely generate a C-terminally truncated protein with a distinct -1 reading-frame terminus. Study of the transcripts extracted from affected subjects' leukocytes confirmed expression of both wild-type and variant alleles, supporting the hypothesis that mutant mRNA escapes NMD. Genomic variants identified in our study suggest that truncation of the C-terminal domain of DVL1, a protein hypothesized to have a downstream role in the Wnt-5a non-canonical pathway, is a common cause of DRS. PMID:25817016

  6. Phenotypic variability of CLDN14 mutations causing DFNB29 hearing loss in the Pakistani population

    PubMed Central

    Bashir, Zil-e-Huma; Latief, Noreen; Belyantseva, Inna A.; Iqbal, Farheena; Riazuddin, S. Amer; Khan, Shaheen N.; Friedman, Thomas B.; Riazuddin, Sheikh; Riazuddin, Saima

    2013-01-01

    Human hereditary deafness at the DFNB29 autosomal locus on chromosome 21q22.1 is caused by recessive mutations of CLDN14, encoding claudin 14. This tight junction protein is tetra-membrane spanning that localizes to the apical tight junctions of organ of Corti hair cells and in many other tissues. Typically, the DFNB29 phenotype is characterized by pre-lingual, bi-lateral, sensorineural hearing loss. The goal of this study was to define the identity and frequency of CLDN14 mutations and associated inner ear phenotypes in a cohort of 800 Pakistani families segregating deafness. Hearing loss in 15 multi-generational families was found to co-segregate with CLDN14-linked STR markers. The sequence of the six exons and regions flanking the introns of CLDN14 in these 15 families revealed five likely pathogenic alleles. Two are novel missense substitutions (p.Ser87Ile and p.Ala94Val) while p.Arg81His, p.Val85Asp and p.Met133ArgfsX23 have been reported previously. Haplotype analyses indicate that p.Val85Asp and p.Met133ArgfsX23 are founder mutations. The p.Val85Asp accounts for approximately 67% of the mutant alleles of CLDN14 in our cohort. Combined with previously reported data, CLDN14 mutations were identified in 18 of 800 Pakistani families (2.25%; 95% CI, 1.4-3.5%). Hearing loss in the affected individuals homozygous for CLDN14 mutations varied from moderate to profound. This phenotypic variability may be due to environmental factors (e.g. drug and noise exposure) and/or genetic modifiers. PMID:23235333

  7. Mutations in CEP120 cause Joubert syndrome as well as complex ciliopathy phenotypes

    PubMed Central

    Romani, Marta; Isrie, Mala; Rosti, Rasim Ozgur; Micalizzi, Alessia; Musaev, Damir; Mazza, Tommaso; Al-gazali, Lihadh; Altunoglu, Umut; Boltshauser, Eugen; D'Arrigo, Stefano; De Keersmaecker, Bart; Kayserili, Hülya; Brandenberger, Sarah; Kraoua, Ichraf; Mark, Paul R; McKanna, Trudy; Van Keirsbilck, Joachim; Moerman, Philippe; Poretti, Andrea; Puri, Ratna; Van Esch, Hilde; Gleeson, Joseph G; Valente, Enza Maria

    2016-01-01

    Background Ciliopathies are an extensive group of autosomal recessive or X-linked disorders with considerable genetic and clinical overlap, which collectively share multiple organ involvement and may result in lethal or viable phenotypes. In large numbers of cases the genetic defect remains yet to be determined. The aim of this study is to describe the mutational frequency and phenotypic spectrum of the CEP120 gene. Methods Exome sequencing was performed in 145 patients with Joubert syndrome (JS), including 15 children with oral-facial-digital syndrome type VI (OFDVI) and 21 Meckel syndrome (MKS) fetuses. Moreover, exome sequencing was performed in one fetus with tectocerebellar dysraphia with occipital encephalocele (TCDOE), molar tooth sign and additional skeletal abnormalities. As a parallel study, 346 probands with a phenotype consistent with JS or related ciliopathies underwent next-generation sequencing-based targeted sequencing of 120 previously described and candidate ciliopathy genes. Results We present six probands carrying nine distinct mutations (of which eight are novel) in the CEP120 gene, previously found mutated only in Jeune asphyxiating thoracic dystrophy (JATD). The CEP120-associated phenotype ranges from mild classical JS in four patients to more severe conditions in two fetuses, with overlapping features of distinct ciliopathies that include TCDOE, MKS, JATD and OFD syndromes. No obvious correlation is evident between the type or location of identified mutations and the ciliopathy phenotype. Conclusion Our findings broaden the spectrum of phenotypes caused by CEP120 mutations that account for nearly 1% of patients with JS as well as for more complex ciliopathy phenotypes. The lack of clear genotype–phenotype correlation highlights the relevance of comprehensive genetic analyses in the diagnostics of ciliopathies. PMID:27208211

  8. The Effect of Inbreeding on the Distribution of Compound Heterozygotes: A Lesson from Lipase H Mutations in Autosomal Recessive Woolly Hair/Hypotrichosis

    PubMed Central

    Petukhova, Lynn; Shimomura, Yutaka; Wajid, Muhammad; Gorroochurn, Prakash; Hodge, Susan E.; Christiano, Angela M.

    2009-01-01

    Autozygosity mapping in consanguineous families has proven to be a powerful method for identifying recessive disease genes. Using this technique with whole genome SNP data generated from low density mapping arrays, we previously identified two genes that underlie autosomal recessive woolly hair (ARWH/hypotrichosis; OMIM278150), specifically P2RY5 and Lipase H (LIPH). In the current study, we sought to identify a novel disease locus for ARWH/hypotrichosis by analyzing two large consanguineous families from Pakistan who had initially been excluded for mutations at either of these disease loci by haplotype analysis with microsatellite markers. A genome-wide analysis of 10 members from each of the two families failed to identify significant regions of autozygosity or linkage. Upon genotyping an additional 10 family members in one of the families, parametric linkage analysis identified a region on chromosome 3q27 with evidence for linkage (Z = 2.5). Surprisingly, this region contains the LIPH gene. Microsatellite markers located within the LIPH gene were used for haplotype analysis and demonstrated that not one, but two haplotypes were segregating with the phenotype in each of these families. DNA sequencing identified two distinct LIPH mutations (280_369dup90 and 659_660delTA). Each affected individual (n = 38) was either homozygous for one mutation (n = 7 and 16 respectively), or compound heterozygous (n = 15). A review of the literature identified several reports of compound heterozygotes in consanguineous families. Prompted by this finding, we derived the probability that a patient affected with a recessive disease is carrying two mutations at the disease locus. We suggest that the validity of the IBD assumption may be challenged in large consanguineous families. PMID:19365138

  9. 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

  10. Compound heterozygous PNPLA6 mutations cause Boucher–Neuhäuser syndrome with late-onset ataxia

    PubMed Central

    Deik, A.; Johannes, B.; Rucker, J. C.; Sánchez, E.; Brodie, S. E.; Deegan, E.; Landy, K.; Kajiwara, Y.; Scelsa, S.; Saunders-Pullman, R.

    2014-01-01

    PNPLA6 mutations, known to be associated with the development of motor neuron phenotypes, have recently been identified in families with Boucher–Neuhäuser syndrome. Boucher–Neuhäuser is a rare autosomal recessive syndrome characterized by the co-occurrence of cerebellar ataxia, hypogonadotropic hypogonadism, and chorioretinal dystrophy. Gait ataxia in Boucher–Neuhäuser usually manifests before early adulthood, although onset in the third or fourth decade has also been reported. However, given the recent identification of PNPLA6 mutations as the cause of this condition, the determining factors of age of symptom onset still need to be established. Here, we have identified a sporadic Boucher–Neuhäuser case with late-onset gait ataxia and relatively milder retinal changes due to compound heterozygous PNPLA6 mutations. Compound heterozygosity was confirmed by cloning and sequencing the patient’s genomic DNA from coding exons 26–29. Furthermore, both mutations (one novel and one known) fell in the phospholipase esterase domain, where most pathogenic mutations seem to cluster. Taken together, we herein confirm PNPLA6 mutations as the leading cause of Boucher–Neuhäuser syndrome and suggest inquiring about a history of hypogonadism or visual changes in patients presenting with late-onset gait ataxia. We also advocate for neuroophthalmologic evaluation in suspected cases. PMID:25267340

  11. Compound heterozygous PNPLA6 mutations cause Boucher-Neuhäuser syndrome with late-onset ataxia.

    PubMed

    Deik, A; Johannes, B; Rucker, J C; Sánchez, E; Brodie, S E; Deegan, E; Landy, K; Kajiwara, Y; Scelsa, S; Saunders-Pullman, R; Paisán-Ruiz, C

    2014-12-01

    PNPLA6 mutations, known to be associated with the development of motor neuron phenotypes, have recently been identified in families with Boucher-Neuhäuser syndrome. Boucher-Neuhäuser is a rare autosomal recessive syndrome characterized by the co-occurrence of cerebellar ataxia, hypogonadotropic hypogonadism, and chorioretinal dystrophy. Gait ataxia in Boucher-Neuhäuser usually manifests before early adulthood, although onset in the third or fourth decade has also been reported. However, given the recent identification of PNPLA6 mutations as the cause of this condition, the determining factors of age of symptom onset still need to be established. Here, we have identified a sporadic Boucher-Neuhäuser case with late-onset gait ataxia and relatively milder retinal changes due to compound heterozygous PNPLA6 mutations. Compound heterozygosity was confirmed by cloning and sequencing the patient's genomic DNA from coding exons 26-29. Furthermore, both mutations (one novel and one known) fell in the phospholipase esterase domain, where most pathogenic mutations seem to cluster. Taken together, we herein confirm PNPLA6 mutations as the leading cause of Boucher-Neuhäuser syndrome and suggest inquiring about a history of hypogonadism or visual changes in patients presenting with late-onset gait ataxia. We also advocate for neuroophthalmologic evaluation in suspected cases.

  12. Compound heterozygous PNPLA6 mutations cause Boucher-Neuhäuser syndrome with late-onset ataxia.

    PubMed

    Deik, A; Johannes, B; Rucker, J C; Sánchez, E; Brodie, S E; Deegan, E; Landy, K; Kajiwara, Y; Scelsa, S; Saunders-Pullman, R; Paisán-Ruiz, C

    2014-12-01

    PNPLA6 mutations, known to be associated with the development of motor neuron phenotypes, have recently been identified in families with Boucher-Neuhäuser syndrome. Boucher-Neuhäuser is a rare autosomal recessive syndrome characterized by the co-occurrence of cerebellar ataxia, hypogonadotropic hypogonadism, and chorioretinal dystrophy. Gait ataxia in Boucher-Neuhäuser usually manifests before early adulthood, although onset in the third or fourth decade has also been reported. However, given the recent identification of PNPLA6 mutations as the cause of this condition, the determining factors of age of symptom onset still need to be established. Here, we have identified a sporadic Boucher-Neuhäuser case with late-onset gait ataxia and relatively milder retinal changes due to compound heterozygous PNPLA6 mutations. Compound heterozygosity was confirmed by cloning and sequencing the patient's genomic DNA from coding exons 26-29. Furthermore, both mutations (one novel and one known) fell in the phospholipase esterase domain, where most pathogenic mutations seem to cluster. Taken together, we herein confirm PNPLA6 mutations as the leading cause of Boucher-Neuhäuser syndrome and suggest inquiring about a history of hypogonadism or visual changes in patients presenting with late-onset gait ataxia. We also advocate for neuroophthalmologic evaluation in suspected cases. PMID:25267340

  13. TOR1AIP1 as a cause of cardiac failure and recessive limb-girdle muscular dystrophy.

    PubMed

    Ghaoui, Roula; Benavides, Tatiana; Lek, Monkol; Waddell, Leigh B; Kaur, Simranpreet; North, Kathryn N; MacArthur, Daniel G; Clarke, Nigel F; Cooper, Sandra T

    2016-08-01

    TorsinA-interacting protein 1 (TOR1AIP1) gene is a novel gene that has recently been described to cause limb-girdle muscular dystrophy (LGMD) with mild dilated cardiomyopathy. We report a family with mutations in TOR1AIP1 where the striking clinical feature is severe cardiac failure requiring cardiac transplant in two siblings, in addition to musculoskeletal weakness and muscular dystrophy. We demonstrate an absence of TOR1AIP1 protein expression in cardiac and skeletal muscles of affected siblings. We expand the phenotype of this gene to demonstrate the cardiac involvement and the importance of cardiac surveillance in patients with mutations in TOR1AIP1.

  14. Novel mutations in PXDN cause microphthalmia and anterior segment dysgenesis.

    PubMed

    Choi, Alex; Lao, Richard; Ling-Fung Tang, Paul; Wan, Eunice; Mayer, Wasima; Bardakjian, Tanya; Shaw, Gary M; Kwok, Pui-Yan; Schneider, Adele; Slavotinek, Anne

    2015-03-01

    We used exome sequencing to study a non-consanguineous family with two children who had anterior segment dysgenesis, sclerocornea, microphthalmia, hypotonia and developmental delays. Sanger sequencing verified two Peroxidasin (PXDN) mutations in both sibs--a maternally inherited, nonsense mutation, c.1021C>T predicting p.(Arg341*), and a paternally inherited, 23-basepair deletion causing a frameshift and premature protein truncation, c.2375_2397del23, predicting p.(Leu792Hisfs*67). We re-examined exome data from 20 other patients with structural eye defects and identified two additional PXDN mutations in a sporadic male with bilateral microphthalmia, cataracts and anterior segment dysgenesis--a maternally inherited, frameshift mutation, c.1192delT, predicting p.(Tyr398Thrfs*40) and a paternally inherited, missense substitution that was predicted to be deleterious, c.947 A>C, predicting p.(Gln316Pro). Mutations in PXDN were previously reported in three families with congenital cataracts, microcornea, sclerocornea and developmental glaucoma. The gene is expressed in corneal epithelium and is secreted into the extracellular matrix. Defective peroxidasin has been shown to impair sulfilimine bond formation in collagen IV, a constituent of the basement membrane, implying that the eye defects result because of loss of basement membrane integrity in the developing eye. Our finding of a broader phenotype than previously appreciated for PXDN mutations is typical for exome-sequencing studies, which have proven to be highly effective for mutation detection in patients with atypical presentations. We conclude that PXDN sequencing should be considered in microphthalmia with anterior segment dysgenesis.

  15. Refsum disease is caused by mutations in the phytanoyl-CoA hydroxylase gene.

    PubMed

    Jansen, G A; Ofman, R; Ferdinandusse, S; Ijlst, L; Muijsers, A O; Skjeldal, O H; Stokke, O; Jakobs, C; Besley, G T; Wraith, J E; Wanders, R J

    1997-10-01

    Refsum disease is an autosomal-recessively inherited disorder characterized clinically by a tetrad of abnormalities: retinitis pigmentosa, peripheral neuropathy, cerebellar ataxia and elevated protein levels in the cerebrospinal fluid (CSF) without an increase in the number of cells in the CSF. All patients exhibit accumulation of an unusual branched-chain fatty acid, phytanic acid (3,7,11,15-tetramethylhexadecanoic acid), in blood and tissues. Biochemically, the disease is caused by the deficiency of phytanoyl-CoA hydroxylase (PhyH), a peroxisomal protein catalyzing the first step in the alpha-oxidation of phytanic acid. We have purified PhyH from rat-liver peroxisomes and determined the N-terminal amino-acid sequence, as well as an additional internal amino-acid sequence obtained after Lys-C digestion of the purified protein. A search of the EST database with these partial amino-acid sequences led to the identification of the full-length human cDNA sequence encoding PhyH: the open reading frame encodes a 41.2-kD protein of 338 amino acids, which contains a cleavable peroxisomal targeting signal type 2 (PTS2). Sequence analysis of PHYH fibroblast cDNA from five patients with Refsum disease revealed distinct mutations, including a one-nucleotide deletion, a 111-nucleotide deletion and a point mutation. This analysis confirms our finding that Refsum disease is caused by a deficiency of PhyH.

  16. Dominant spinal muscular atrophy is caused by mutations in BICD2, an important golgin protein

    PubMed Central

    Martinez-Carrera, Lilian A.; Wirth, Brunhilde

    2015-01-01

    Spinal muscular atrophies (SMAs) are characterized by degeneration of spinal motor neurons and muscle weakness. Autosomal recessive SMA is the most common form and is caused by homozygous deletions/mutations of the SMN1 gene. However, families with dominant inherited SMA have been reported, for most of them the causal gene remains unknown. Recently, we and others have identified heterozygous mutations in BICD2 as causative for autosomal dominant SMA, lower extremity-predominant, 2 (SMALED2) and hereditary spastic paraplegia (HSP). BICD2 encodes the Bicaudal D2 protein, which is considered to be a golgin, due to its coiled-coil (CC) structure and interaction with the small GTPase RAB6A located at the Golgi apparatus. Golgins are resident proteins in the Golgi apparatus and form a matrix that helps to maintain the structure of this organelle. Golgins are also involved in the regulation of vesicle transport. In vitro overexpression experiments and studies of fibroblast cell lines derived from patients, showed fragmentation of the Golgi apparatus. In the current review, we will discuss possible causes for this disruption, and the consequences at cellular level, with a view to better understand the pathomechanism of this disease. PMID:26594138

  17. Red cell glycolytic enzyme disorders caused by mutations: an update.

    PubMed

    Climent, Fernando; Roset, Feliu; Repiso, Ada; Pérez de la Ossa, Pablo

    2009-06-01

    Glycolysis is one of the principle pathways of ATP generation in cells and is present in all cell tissues; in erythrocytes, glycolysis is the only pathway for ATP synthesis since mature red cells lack the internal structures necessary to produce the energy vital for life. Red cell deficiencies have been detected in all erythrocyte glycolytic pathways, although their frequencies differ owing to diverse causes, such as the affected enzyme and severity of clinical manifestations. The number of enzyme deficiencies known is endless. The most frequent glycolysis abnormality is pyruvate kinase deficiency, since around 500 cases are known, the first of which was reported in 1961. However, only approximately 200 cases were due to mutations. In contrast, only one case of phosphoglycerate mutase BB type mutation, described in 2003, has been detected. Most mutations are located in the coding sequences of genes, while others, missense, deletions, insertions, splice defects, premature stop codons and promoter mutations, are also frequent. Understanding of the crystal structure of enzymes permits molecular modelling studies which, in turn, reveal how mutations can affect enzyme structure and function. PMID:19519368

  18. An MRPS12 mutation modifies aminoglycoside sensitivity caused by 12S rRNA mutations

    PubMed Central

    Emperador, Sonia; Pacheu-Grau, David; Bayona-Bafaluy, M. Pilar; Garrido-Pérez, Nuria; Martín-Navarro, Antonio; López-Pérez, Manuel J.; Montoya, Julio; Ruiz-Pesini, Eduardo

    2015-01-01

    Several homoplasmic pathologic mutations in mitochondrial DNA, such as those causing Leber hereditary optic neuropathy or non-syndromic hearing loss, show incomplete penetrance. Therefore, other elements must modify their pathogenicity. Discovery of these modifying factors is not an easy task because in multifactorial diseases conventional genetic approaches may not always be informative. Here, we have taken an evolutionary approach to unmask putative modifying factors for a particular homoplasmic pathologic mutation causing aminoglycoside-induced and non-syndromic hearing loss, the m.1494C>T transition in the mitochondrial DNA. The mutation is located in the decoding site of the mitochondrial ribosomal RNA. We first looked at mammalian species that had fixed the human pathologic mutation. These mutations are called compensated pathogenic deviations because an organism carrying one must also have another that suppresses the deleterious effect of the first. We found that species from the primate family Cercopithecidae (old world monkeys) harbor the m.1494T allele even if their auditory function is normal. In humans the m.1494T allele increases the susceptibility to aminoglycosides. However, in primary fibroblasts from a Cercopithecidae species, aminoglycosides do not impair cell growth, respiratory complex IV activity and quantity or the mitochondrial protein synthesis. Interestingly, this species also carries a fixed mutation in the mitochondrial ribosomal protein S12. We show that the expression of this variant in a human m.1494T cell line reduces its susceptibility to aminoglycosides. Because several mutations in this human protein have been described, they may possibly explain the absence of pathologic phenotype in some pedigree members with the most frequent pathologic mutations in mitochondrial ribosomal RNA. PMID:25642242

  19. ARHGDIA mutations cause nephrotic syndrome via defective RHO GTPase signaling

    PubMed Central

    Gee, Heon Yung; Saisawat, Pawaree; Ashraf, Shazia; Hurd, Toby W.; Vega-Warner, Virginia; Fang, Humphrey; Beck, Bodo B.; Gribouval, Olivier; Zhou, Weibin; Diaz, Katrina A.; Natarajan, Sivakumar; Wiggins, Roger C.; Lovric, Svjetlana; Chernin, Gil; Schoeb, Dominik S.; Ovunc, Bugsu; Frishberg, Yaacov; Soliman, Neveen A.; Fathy, Hanan M.; Goebel, Heike; Hoefele, Julia; Weber, Lutz T.; Innis, Jeffrey W.; Faul, Christian; Han, Zhe; Washburn, Joseph; Antignac, Corinne; Levy, Shawn; Otto, Edgar A.; Hildebrandt, Friedhelm

    2013-01-01

    Nephrotic syndrome (NS) is divided into steroid-sensitive (SSNS) and -resistant (SRNS) variants. SRNS causes end-stage kidney disease, which cannot be cured. While the disease mechanisms of NS are not well understood, genetic mapping studies suggest a multitude of unknown single-gene causes. We combined homozygosity mapping with whole-exome resequencing and identified an ARHGDIA mutation that causes SRNS. We demonstrated that ARHGDIA is in a complex with RHO GTPases and is prominently expressed in podocytes of rat glomeruli. ARHGDIA mutations (R120X and G173V) from individuals with SRNS abrogated interaction with RHO GTPases and increased active GTP-bound RAC1 and CDC42, but not RHOA, indicating that RAC1 and CDC42 are more relevant to the pathogenesis of this SRNS variant than RHOA. Moreover, the mutations enhanced migration of cultured human podocytes; however, enhanced migration was reversed by treatment with RAC1 inhibitors. The nephrotic phenotype was recapitulated in arhgdia-deficient zebrafish. RAC1 inhibitors were partially effective in ameliorating arhgdia-associated defects. These findings identify a single-gene cause of NS and reveal that RHO GTPase signaling is a pathogenic mediator of SRNS. PMID:23867502

  20. MMP13 mutation causes spondyloepimetaphyseal dysplasia, Missouri type (SEMDMO)

    PubMed Central

    Kennedy, Ann M.; Inada, Masaki; Krane, Stephen M.; Christie, Paul T.; Harding, Brian; López-Otín, Carlos; Sánchez, Luis M.; Pannett, Anna A.J.; Dearlove, Andrew; Hartley, Claire; Byrne, Michael H.; Reed, Anita A.C.; Nesbit, M. Andrew; Whyte, Michael P.; Thakker, Rajesh V.

    2005-01-01

    MMPs, which degrade components of the ECM, have roles in embryonic development, tissue repair, cancer, arthritis, and cardiovascular disease. We show that a missense mutation of MMP13 causes the Missouri type of human spondyloepimetaphyseal dysplasia (SEMDMO), an autosomal dominant disorder characterized by defective growth and modeling of vertebrae and long bones. Genome-wide linkage analysis mapped SEMDMO to a 17-cM region on chromosome 11q14.3–23.2 that contains a cluster of 9 MMP genes. Among these, MMP13 represented the best candidate for SEMDMO, since it preferentially degrades collagen type II, abnormalities of which cause skeletal dysplasias that include Strudwick type SEMD. DNA sequence analysis revealed a missense mutation, F56S, that substituted an evolutionarily conserved phenylalanine residue for a serine in the proregion domain of MMP13. We predicted, by modeling MMP13 structure, that this F56S mutation would result in a hydrophobic cavity with misfolding, autoactivation, and degradation of mutant protein intracellularly. Expression of wild-type and mutant MMP13s in human embryonic kidney cells confirmed abnormal intracellular autoactivation and autodegradation of F56S MMP13 such that only enzymatically inactive, small fragments were secreted. Thus, the F56S mutation results in deficiency of MMP13, which leads to the human skeletal developmental anomaly of SEMDMO. PMID:16167086

  1. Fine mapping and discovery of recessive mutations that cause abortions in dairy cattle

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods to trace the inheritance of 5 haplotypes affecting fertility (HH1, HH2, HH3, JH1, and BH1) were improved and implemented in December 2011. Programs that detect these haplotypes were modified to narrow the suspect region and detect additional crossover haplotypes believed to carry the lethal ...

  2. Recessive mutations in DOCK6, encoding the guanidine nucleotide exchange factor DOCK6, lead to abnormal actin cytoskeleton organization and Adams-Oliver syndrome.

    PubMed

    Shaheen, Ranad; Faqeih, Eissa; Sunker, Asma; Morsy, Heba; Al-Sheddi, Tarfa; Shamseldin, Hanan E; Adly, Nouran; Hashem, Mais; Alkuraya, Fowzan S

    2011-08-12

    Adams-Oliver syndrome (AOS) is defined by the combination of aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). It is usually inherited as an autosomal-dominant trait, but autosomal-recessive inheritance has also been documented. In an individual with autosomal-recessive AOS, we combined autozygome analysis with exome sequencing to identify a homozygous truncating mutation in dedicator of cytokinesis 6 gene (DOCK6) which encodes an atypical guanidine exchange factor (GEF) known to activate two members of the Rho GTPase family: Cdc42 and Rac1. Another homozygous truncating mutation was identified upon targeted sequencing of DOCK6 in an unrelated individual with AOS. Consistent with the established role of Cdc42 and Rac1 in the organization of the actin cytoskeleton, we demonstrate a cellular phenotype typical of a defective actin cytoskeleton in patient cells. These findings, combined with a Dock6 expression profile that is consistent with an AOS phenotype as well as the very recent demonstration of dominant mutations of ARHGAP31 in AOS, establish Cdc42 and Rac1 as key molecules in the pathogenesis of AOS and suggest that other regulators of these Rho GTPase proteins might be good candidates in the quest to define the genetic spectrum of this genetically heterogeneous condition.

  3. Recessive Mutations in DOCK6, Encoding the Guanidine Nucleotide Exchange Factor DOCK6, Lead to Abnormal Actin Cytoskeleton Organization and Adams-Oliver Syndrome

    PubMed Central

    Shaheen, Ranad; Faqeih, Eissa; Sunker, Asma; Morsy, Heba; Al-Sheddi, Tarfa; Shamseldin, Hanan E.; Adly, Nouran; Hashem, Mais; Alkuraya., Fowzan S.

    2011-01-01

    Adams-Oliver syndrome (AOS) is defined by the combination of aplasia cutis congenita (ACC) and terminal transverse limb defects (TTLD). It is usually inherited as an autosomal-dominant trait, but autosomal-recessive inheritance has also been documented. In an individual with autosomal-recessive AOS, we combined autozygome analysis with exome sequencing to identify a homozygous truncating mutation in dedicator of cytokinesis 6 gene (DOCK6) which encodes an atypical guanidine exchange factor (GEF) known to activate two members of the Rho GTPase family: Cdc42 and Rac1. Another homozygous truncating mutation was identified upon targeted sequencing of DOCK6 in an unrelated individual with AOS. Consistent with the established role of Cdc42 and Rac1 in the organization of the actin cytoskeleton, we demonstrate a cellular phenotype typical of a defective actin cytoskeleton in patient cells. These findings, combined with a Dock6 expression profile that is consistent with an AOS phenotype as well as the very recent demonstration of dominant mutations of ARHGAP31 in AOS, establish Cdc42 and Rac1 as key molecules in the pathogenesis of AOS and suggest that other regulators of these Rho GTPase proteins might be good candidates in the quest to define the genetic spectrum of this genetically heterogeneous condition. PMID:21820096

  4. Mutations in the pericentrin (PCNT) gene cause primordial dwarfism.

    PubMed

    Rauch, Anita; Thiel, Christian T; Schindler, Detlev; Wick, Ursula; Crow, Yanick J; Ekici, Arif B; van Essen, Anthonie J; Goecke, Timm O; Al-Gazali, Lihadh; Chrzanowska, Krystyna H; Zweier, Christiane; Brunner, Han G; Becker, Kristin; Curry, Cynthia J; Dallapiccola, Bruno; Devriendt, Koenraad; Dörfler, Arnd; Kinning, Esther; Megarbane, André; Meinecke, Peter; Semple, Robert K; Spranger, Stephanie; Toutain, Annick; Trembath, Richard C; Voss, Egbert; Wilson, Louise; Hennekam, Raoul; de Zegher, Francis; Dörr, Helmuth-Günther; Reis, André

    2008-02-01

    Fundamental processes influencing human growth can be revealed by studying extreme short stature. Using genetic linkage analysis, we find that biallelic loss-of-function mutations in the centrosomal pericentrin (PCNT) gene on chromosome 21q22.3 cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II) in 25 patients. Adults with this rare inherited condition have an average height of 100 centimeters and a brain size comparable to that of a 3-month-old baby, but are of near-normal intelligence. Absence of PCNT results in disorganized mitotic spindles and missegregation of chromosomes. Mutations in related genes are known to cause primary microcephaly (MCPH1, CDK5RAP2, ASPM, and CENPJ). PMID:18174396

  5. Mutations in PCBD1 Cause Hypomagnesemia and Renal Magnesium Wasting

    PubMed Central

    Ferrè, Silvia; de Baaij, Jeroen H.F.; Ferreira, Patrick; Germann, Roger; de Klerk, Johannis B.C.; Lavrijsen, Marla; van Zeeland, Femke; Venselaar, Hanka; Kluijtmans, Leo A.J.; Hoenderop, Joost G.J.

    2014-01-01

    Mutations in PCBD1 are causative for transient neonatal hyperphenylalaninemia and primapterinuria (HPABH4D). Until now, HPABH4D has been regarded as a transient and benign neonatal syndrome without complications in adulthood. In our study of three adult patients with homozygous mutations in the PCBD1 gene, two patients were diagnosed with hypomagnesemia and renal Mg2+ loss, and two patients developed diabetes with characteristics of maturity onset diabetes of the young (MODY), regardless of serum Mg2+ levels. Our results suggest that these clinical findings are related to the function of PCBD1 as a dimerization cofactor for the transcription factor HNF1B. Mutations in the HNF1B gene have been shown to cause renal malformations, hypomagnesemia, and MODY. Gene expression studies combined with immunohistochemical analysis in the kidney showed that Pcbd1 is expressed in the distal convoluted tubule (DCT), where Pcbd1 transcript levels are upregulated by a low Mg2+-containing diet. Overexpression in a human kidney cell line showed that wild-type PCBD1 binds HNF1B to costimulate the FXYD2 promoter, the activity of which is instrumental in Mg2+ reabsorption in the DCT. Of seven PCBD1 mutations previously reported in HPABH4D patients, five mutations caused proteolytic instability, leading to reduced FXYD2 promoter activity. Furthermore, cytosolic localization of PCBD1 increased when coexpressed with HNF1B mutants. Overall, our findings establish PCBD1 as a coactivator of the HNF1B-mediated transcription necessary for fine tuning FXYD2 transcription in the DCT and suggest that patients with HPABH4D should be monitored for previously unrecognized late complications, such as hypomagnesemia and MODY diabetes. PMID:24204001

  6. Mutation in BAG3 Causes Severe Dominant Childhood Muscular Dystrophy

    PubMed Central

    Selcen, Duygu; Muntoni, Francesco; Burton, Barbara K.; MD, Elena Pegoraro; Sewry, Caroline; Bite, Anna V.; Engel, Andrew G.

    2008-01-01

    Objective Myofibrillar myopathies (MFM) are morphologically distinct but genetically heterogeneous muscular dystrophies in which disintegration of Z disks and then of myofibrils is followed by ectopic accumulation of multiple proteins. Cardiomyopathy, neuropathy, and dominant inheritance are frequent associated features. Mutations in αB-crystallin, desmin, myotilin, Zasp, or filamin-C can cause MFM, and were detected in 32/85 patients of the Mayo MFM cohort. Bag3, another Z-disk associated protein, has antiapoptotic properties and its targeted deletion in mice causes fulminant myopathy with early lethality. We therefore searched for mutations in BAG3 in 53 unrelated MFM patients. Methods We searched for mutations in BAG3 by direct sequencing and excluded polymorphism using allele-specific PCR in relatives and 200 control subjects. We analyzed structural changes in muscle by histochemistry, immunocytochemistry and electron microscopy, examined mobility of the mutant Bag3 by nondenaturing electrophoresis, and searched for abnormal aggregation of the mutant protein in COS-7 cells. Results We identified a heterozygous p.Pro209Leu mutation in three patients. All presented in childhood, had progressive limb and axial muscle weakness, and developed cardiomyopathy and severe respiratory insufficiency in their teens; two had rigid spines and one a peripheral neuropathy. Electron microscopy showed disintegration of Z disks, extensive accumulation of granular debris and larger inclusions, and apoptosis of 8% of the nuclei. On nondenaturing electrophoresis of muscle extracts, the Bag3 complex migrated faster in patient than control extracts, and expression of FLAG-labeled mutant and wild-type Bag3 in COS cells revealed abnormal aggregation of the mutant protein. Interpretation We conclude mutation in Bag3 defines a novel severe autosomal dominant childhood muscular dystrophy. PMID:19085932

  7. Mutations in the human CYP11B2 (aldosterone synthase) gene causing corticosterone methyloxidase II deficiency.

    PubMed Central

    Pascoe, L; Curnow, K M; Slutsker, L; Rösler, A; White, P C

    1992-01-01

    Corticosterone methyloxidase II (CMO-II) deficiency is an autosomal recessive disorder of aldosterone biosynthesis, characterized by an elevated ratio of 18-hydroxycorticosterone to aldosterone in serum. It is genetically linked to the CYP11B1 and CYP11B2 genes that, respectively, encode two cytochrome P450 isozymes, P450XIB1 and P450XIB2. Whereas P450XIB1 only catalyzes hydroxylation at position 11 beta of 11-deoxycorticosterone and 11-deoxycortisol, P450XIB2 catalyzes the synthesis of aldosterone from deoxycorticosterone, a process that successively requires hydroxylation at positions 11 beta and 18 and oxidation at position 18. To determine the molecular genetic basis of CMO-II deficiency, seven kindreds of Iranian-Jewish origin were studied in which members suffered from CMO-II deficiency. No mutations were found in the CYP11B1 genes, but two candidate mutations, R181W and V386A, were found in the CYP11B2 genes. When these mutations were individually introduced into CYP11B2 cDNA and expressed in cultured cells, R181W reduced 18-hydroxylase and abolished 18-oxidase activities but left 11 beta-hydroxylase activity intact, whereas V386A caused a small but consistent reduction in the production of 18-hydroxycorticosterone. All individuals affected with CMO-II deficiency were homozygous for both mutations, whereas eight asymptomatic subjects were homozygous for R181W alone and three were homozygous for V386A alone. These findings confirm that P450XIB2 is the major enzyme mediating oxidation at position 18 in the adrenal and suggest that a small amount of residual activity undetectable in in vitro assays is sufficient to synthesize normal amounts of aldosterone. Images PMID:1594605

  8. Mutations in CKAP2L, the Human Homolog of the Mouse Radmis Gene, Cause Filippi Syndrome

    PubMed Central

    Hussain, Muhammad Sajid; Battaglia, Agatino; Szczepanski, Sandra; Kaygusuz, Emrah; Toliat, Mohammad Reza; Sakakibara, Shin-ichi; Altmüller, Janine; Thiele, Holger; Nürnberg, Gudrun; Moosa, Shahida; Yigit, Gökhan; Beleggia, Filippo; Tinschert, Sigrid; Clayton-Smith, Jill; Vasudevan, Pradeep; Urquhart, Jill E.; Donnai, Dian; Fryer, Alan; Percin, Ferda; Brancati, Francesco; Dobbie, Angus; Śmigiel, Robert; Gillessen-Kaesbach, Gabriele; Wollnik, Bernd; Noegel, Angelika Anna; Newman, William G.; Nürnberg, Peter

    2014-01-01

    Filippi syndrome is a rare, presumably autosomal-recessive disorder characterized by microcephaly, pre- and postnatal growth failure, syndactyly, and distinctive facial features, including a broad nasal bridge and underdeveloped alae nasi. Some affected individuals have intellectual disability, seizures, undescended testicles in males, and teeth and hair abnormalities. We performed homozygosity mapping and whole-exome sequencing in a Sardinian family with two affected children and identified a homozygous frameshift mutation, c.571dupA (p.Ile191Asnfs∗6), in CKAP2L, encoding the protein cytoskeleton-associated protein 2-like (CKAP2L). The function of this protein was unknown until it was rediscovered in mice as Radmis (radial fiber and mitotic spindle) and shown to play a pivotal role in cell division of neural progenitors. Sanger sequencing of CKAP2L in a further eight unrelated individuals with clinical features consistent with Filippi syndrome revealed biallelic mutations in four subjects. In contrast to wild-type lymphoblastoid cell lines (LCLs), dividing LCLs established from the individuals homozygous for the c.571dupA mutation did not show CKAP2L at the spindle poles. Furthermore, in cells from the affected individuals, we observed an increase in the number of disorganized spindle microtubules owing to multipolar configurations and defects in chromosome segregation. The observed cellular phenotypes are in keeping with data from in vitro and in vivo knockdown studies performed in human cells and mice, respectively. Our findings show that loss-of-function mutations in CKAP2L are a major cause of Filippi syndrome. PMID:25439729

  9. A Novel Homozygous Mutation in FOXC1 Causes Axenfeld Rieger Syndrome with Congenital Glaucoma

    PubMed Central

    Micheal, Shazia; Villanueva-Mendoza, Cristina; Cortés-González, Vianney; Khan, Muhammad Imran; den Hollander, Anneke I.

    2016-01-01

    Background Anterior segment dysgenesis (ASD) disorders are a group of clinically and genetically heterogeneous phenotypes in which frequently cornea, iris, and lens are affected. This study aimed to identify novel mutations in PAX6, PITX2 and FOXC1 in families with anterior segment dysgenesis disorders. Methods We studied 14 Pakistani and one Mexican family with Axenfeld Rieger syndrome (ARS; n = 10) or aniridia (n = 5). All affected and unaffected family members underwent full ophthalmologic and general examinations. Total genomic DNA was isolated from peripheral blood. PCR and Sanger sequencing were performed for the exons and intron-exon boundaries of the FOXC1, PAX6, and PITX2 genes. Results Mutations were identified in five of the 15 probands; four variants were novel and one variant was described previously. A novel de novo variant (c.225C>A; p.Tyr75*) was identified in the PAX6 gene in two unrelated probands with aniridia. In addition, a known variant (c.649C>T; p.Arg217*) in PAX6 segregated in a family with aniridia. In the FOXC1 gene, a novel heterozygous variant (c.454T>C; p.Trp152Arg) segregated with the disease in a Mexican family with ARS. A novel homozygous variant (c.92_100del; p.Ala31_Ala33del) in the FOXC1 gene segregated in a Pakistani family with ARS and congenital glaucoma. Conclusions Our study expands the mutation spectrum of the PAX6 and FOXC1 genes in individuals with anterior segment dysgenesis disorders. In addition, our study suggests that FOXC1 mutations, besides typical autosomal dominant ARS, can also cause ARS with congenital glaucoma through an autosomal recessive inheritance pattern. Our results thus expand the disease spectrum of FOXC1, and may lead to a better understanding of the role of FOXC1 in development. PMID:27463523

  10. Characterization of an apparently synonymous F5 mutation causing aberrant splicing and factor V deficiency.

    PubMed

    Nuzzo, F; Bulato, C; Nielsen, B I; Lee, K; Wielders, S J; Simioni, P; Key, N S; Castoldi, E

    2015-03-01

    Coagulation factor V (FV) deficiency is a rare autosomal recessive bleeding disorder. We investigated a patient with severe FV deficiency (FV:C < 3%) and moderate bleeding symptoms. Thrombin generation experiments showed residual FV expression in the patient's plasma, which was quantified as 0.7 ± 0.3% by a sensitive prothrombinase-based assay. F5 gene sequencing identified a novel missense mutation in exon 4 (c.578G>C, p.Cys193Ser), predicting the abolition of a conserved disulphide bridge, and an apparently synonymous variant in exon 8 (c.1281C>G). The observation that half of the patient's F5 mRNA lacked the last 18 nucleotides of exon 8 prompted us to re-evaluate the c.1281C>G variant for its possible effects on splicing. Bioinformatics sequence analysis predicted that this transversion would activate a cryptic donor splice site and abolish an exonic splicing enhancer. Characterization in a F5 minigene model confirmed that the c.1281C>G variant was responsible for the patient's splicing defect, which could be partially corrected by a mutation-specific morpholino antisense oligonucleotide. The aberrantly spliced F5 mRNA, whose stability was similar to that of the normal mRNA, encoded a putative FV mutant lacking amino acids 427-432. Expression in COS-1 cells indicated that the mutant protein is poorly secreted and not functional. In conclusion, the c.1281C>G mutation, which was predicted to be translationally silent and hence neutral, causes FV deficiency by impairing pre-mRNA splicing. This finding underscores the importance of cDNA analysis for the correct assessment of exonic mutations. PMID:25470420

  11. Progressive hearing loss and vestibular dysfunction caused by a homozygous nonsense mutation in CLIC5

    PubMed Central

    Seco, Celia Zazo; Oonk, Anne MM; Domínguez-Ruiz, María; Draaisma, Jos MT; Gandía, Marta; Oostrik, Jaap; Neveling, Kornelia; Kunst, Henricus PM; Hoefsloot, Lies H; del Castillo, Ignacio; Pennings, Ronald JE; Kremer, Hannie; Admiraal, Ronald JC; Schraders, Margit

    2015-01-01

    In a consanguineous Turkish family diagnosed with autosomal recessive nonsyndromic hearing impairment (arNSHI), a homozygous region of 47.4 Mb was shared by the two affected siblings on chromosome 6p21.1-q15. This region contains 247 genes including the known deafness gene MYO6. No pathogenic variants were found in MYO6, neither with sequence analysis of the coding region and splice sites nor with mRNA analysis. Subsequent candidate gene evaluation revealed CLIC5 as an excellent candidate gene. The orthologous mouse gene is mutated in the jitterbug mutant that exhibits progressive hearing impairment and vestibular dysfunction. Mutation analysis of CLIC5 revealed a homozygous nonsense mutation c.96T>A (p.(Cys32Ter)) that segregated with the hearing loss. Further analysis of CLIC5 in 213 arNSHI patients from mostly Dutch and Spanish origin did not reveal any additional pathogenic variants. CLIC5 mutations are thus not a common cause of arNSHI in these populations. The hearing loss in the present family had an onset in early childhood and progressed from mild to severe or even profound before the second decade. Impaired hearing is accompanied by vestibular areflexia and in one of the patients with mild renal dysfunction. Although we demonstrate that CLIC5 is expressed in many other human tissues, no additional symptoms were observed in these patients. In conclusion, our results show that CLIC5 is a novel arNSHI gene involved in progressive hearing impairment, vestibular and possibly mild renal dysfunction in a family of Turkish origin. PMID:24781754

  12. Study of radiosensitive Drosophila lines. XI. Induction of recessive sex-linked lethal mutations in females of the mutant line rad(2)201/sup G1/

    SciTech Connect

    Varentsova, E.R.

    1986-05-01

    The authors have studied the frequency of occurrence of recessive sex-linked lethal mutations (RSLLM) after treatment of the females with ..gamma..-rays as a function of the dose (from 5 to 20 Gy) and oogenesis stage. They have shown that within the dose range used the oocytes of the 14th and 7th development stage are more sensitive in females of the mutant line than in those of the control. They detected significant differences in the frequency of occurrence of RSLLM between the 14th and 7th stages of development of oocytes for both Drosophila lines investigated.

  13. A novel Gypsy founder mutation, p.Arg1109X in the CMT4C gene, causes variable peripheral neuropathy phenotypes

    PubMed Central

    Gooding, R; Colomer, J; King, R; Angelicheva, D; Marns, L; Parman, Y; Chandler, D; Bertranpetit, J; Kalaydjieva, L

    2005-01-01

    Background: Linkage, haplotype and sequencing analysis in a large Spanish Gypsy kindred with multiple members affected by autosomal recessive peripheral neuropathy led to the identification of a novel mutation, p.Arg1109X, in the CMT4C gene. The screening of further unrelated patients, and of a panel of ethnically matched controls, showed that p.Arg1109X is an ancestral mutation which occurs in Gypsy populations across Europe and is the most common cause of autosomal recessive Charcot–Marie–Tooth disease in Spanish Gypsies. Objective: To report the identification of a novel Gypsy founder mutation causing autosomal recessive CMT4C disease in a sample of homozygous affected individuals. Results: The mutation was associated with a surprisingly broad spectrum of neuropathy phenotypes, with variation in the age at onset, rate of progression, severity of muscle and sensory involvement, the presence of scoliosis, and cranial nerve involvement. Conclusions: Ascertainment and further studies of CMT4C patients in this population will provide a unique opportunity for characterising the full range of clinical manifestations of the disease in a genetically homogeneous sample. PMID:16326826

  14. Hypomaturation Amelogenesis Imperfecta Caused By A Novel SLC24A4 Mutation

    PubMed Central

    Herzog, Curtis R.; Reid, Bryan M.; Seymen, Figen; Koruyucu, Mine; Tuna, Elif Bahar; Simmer, James P.; Hu, Jan C-C.

    2014-01-01

    In this case report of autosomal recessive pigmented hypomaturation amelogenesis imperfecta (AI), we identify a novel homozygous missense mutation (g.165151T>G; c.1317T>G; p.Leu436Arg) in SLC24A4, a gene encoding a potassium-dependent sodium-calcium exchanger that is critical for hardening dental enamel during tooth development. PMID:25442250

  15. Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6

    PubMed Central

    Ratbi, Ilham; Falkenberg, Kim D.; Sommen, Manou; Al-Sheqaih, Nada; Guaoua, Soukaina; Vandeweyer, Geert; Urquhart, Jill E.; Chandler, Kate E.; Williams, Simon G.; Roberts, Neil A.; El Alloussi, Mustapha; Black, Graeme C.; Ferdinandusse, Sacha; Ramdi, Hind; Heimler, Audrey; Fryer, Alan; Lynch, Sally-Ann; Cooper, Nicola; Ong, Kai Ren; Smith, Claire E.L.; Inglehearn, Christopher F.; Mighell, Alan J.; Elcock, Claire; Poulter, James A.; Tischkowitz, Marc; Davies, Sally J.; Sefiani, Abdelaziz; Mironov, Aleksandr A.; Newman, William G.; Waterham, Hans R.; Van Camp, Guy

    2015-01-01

    Heimler syndrome (HS) is a rare recessive disorder characterized by sensorineural hearing loss (SNHL), amelogenesis imperfecta, nail abnormalities, and occasional or late-onset retinal pigmentation. We ascertained eight families affected by HS and, by using a whole-exome sequencing approach, identified biallelic mutations in PEX1 or PEX6 in six of them. Loss-of-function mutations in both genes are known causes of a spectrum of autosomal-recessive peroxisome-biogenesis disorders (PBDs), including Zellweger syndrome. PBDs are characterized by leukodystrophy, hypotonia, SNHL, retinopathy, and skeletal, craniofacial, and liver abnormalities. We demonstrate that each HS-affected family has at least one hypomorphic allele that results in extremely mild peroxisomal dysfunction. Although individuals with HS share some subtle clinical features found in PBDs, the diagnosis was not suggested by routine blood and skin fibroblast analyses used to detect PBDs. In conclusion, our findings define HS as a mild PBD, expanding the pleiotropy of mutations in PEX1 and PEX6. PMID:26387595

  16. Heimler Syndrome Is Caused by Hypomorphic Mutations in the Peroxisome-Biogenesis Genes PEX1 and PEX6.

    PubMed

    Ratbi, Ilham; Falkenberg, Kim D; Sommen, Manou; Al-Sheqaih, Nada; Guaoua, Soukaina; Vandeweyer, Geert; Urquhart, Jill E; Chandler, Kate E; Williams, Simon G; Roberts, Neil A; El Alloussi, Mustapha; Black, Graeme C; Ferdinandusse, Sacha; Ramdi, Hind; Heimler, Audrey; Fryer, Alan; Lynch, Sally-Ann; Cooper, Nicola; Ong, Kai Ren; Smith, Claire E L; Inglehearn, Christopher F; Mighell, Alan J; Elcock, Claire; Poulter, James A; Tischkowitz, Marc; Davies, Sally J; Sefiani, Abdelaziz; Mironov, Aleksandr A; Newman, William G; Waterham, Hans R; Van Camp, Guy

    2015-10-01

    Heimler syndrome (HS) is a rare recessive disorder characterized by sensorineural hearing loss (SNHL), amelogenesis imperfecta, nail abnormalities, and occasional or late-onset retinal pigmentation. We ascertained eight families affected by HS and, by using a whole-exome sequencing approach, identified biallelic mutations in PEX1 or PEX6 in six of them. Loss-of-function mutations in both genes are known causes of a spectrum of autosomal-recessive peroxisome-biogenesis disorders (PBDs), including Zellweger syndrome. PBDs are characterized by leukodystrophy, hypotonia, SNHL, retinopathy, and skeletal, craniofacial, and liver abnormalities. We demonstrate that each HS-affected family has at least one hypomorphic allele that results in extremely mild peroxisomal dysfunction. Although individuals with HS share some subtle clinical features found in PBDs, the diagnosis was not suggested by routine blood and skin fibroblast analyses used to detect PBDs. In conclusion, our findings define HS as a mild PBD, expanding the pleiotropy of mutations in PEX1 and PEX6.

  17. Mutations in TMC1 are a common cause of DFNB7/11 hearing loss in the Iranian population

    PubMed Central

    Hildebrand, Michael S.; Kahrizi, Kimia; Bromhead, Catherine J.; Shearer, A. Eliot; Webster, Jennifer A.; Khodaei, Hossein; Abtahi, Rezvan; Bazazzadegan, Niloofar; Babanejad, Mojgan; Nikzat, Nooshin; Kimberling, William J.; Stephan, Dietrich; Huygen, Partick L.M.; Bahlo, Melanie; Smith, Richard J.H.; Najmabadi, Hossein

    2010-01-01

    Objectives To investigate the cause of autosomal recessive non-syndromic hearing loss (ARNSHL) segregating in two consanguineous Iranian families. Methods Otologic and audiometric examinations were performed on affected members of each family. Genome-wide parametric multipoint linkage mapping using a recessive model was performed with Affymetrix 50K GeneChips or short tandem repeat polymorphisms (STRPs). Direct sequencing was used to confirm the causative mutation in each family. Results In two Iranian families, L-1651 and L-8600606, segregating ARNSHL that mapped to the DFNB7/11 locus, homozygosity for a reported splice site mutation (c.776+1G>A) and a novel deletion (c.1589_1590delCT; p.S530*) were identified in the TMC1 gene, respectively. Conclusions Consistent with the previously reported phenotype in DFNB7/11 families, the two Iranian families segregate congenital, profound hearing impairment. However, in family L-1651 one affected family member (IV:3) has milder hearing impairment than expected, suggesting a potential genetic modifier effect. These results indicate that DFNB7/11 is a common form of genetic hearing loss in Iran since this population is the source of six of the 29 TMC1 mutations reported worldwide. PMID:21250555

  18. SOX2 mutation causes anophthalmia, hearing loss, and brain anomalies.

    PubMed

    Hagstrom, Stephanie A; Pauer, Gayle J T; Reid, Janet; Simpson, Ellen; Crowe, Sue; Maumenee, Irene H; Traboulsi, Elias I

    2005-10-01

    The SOX2 transcription factor is expressed early in the embryonic stem cells of the blastocyst and later in the neural stem cells. It is a member of the SOX family of proteins that carry a DNA-binding high-mobility group domain and additional domains that regulate embryonic development and cell fate determinations. We surveyed 93 patients with severe eye malformations for mutations in SOX2. Here, we report a novel nonsense mutation in one female patient with bilateral clinical anophthalmia, absence of all optic pathways, and other neurological abnormalities. The mutation, Q155X, creates a premature termination codon early in the transcriptional activation domain and is likely to be a null allele. Our data show that mutations in SOX2 can cause not only anophthalmia, but also aplasia of the optic nerve, chiasm and optic tract, as well as modest bilateral sensorineural hearing loss, and global developmental delay, underscoring the importance of SOX2 in early human eye and brain development.

  19. Heterozygous mutations of OTX2 cause severe ocular malformations.

    PubMed

    Ragge, Nicola K; Brown, Alison G; Poloschek, Charlotte M; Lorenz, Birgit; Henderson, R Alex; Clarke, Michael P; Russell-Eggitt, Isabelle; Fielder, Alistair; Gerrelli, Dianne; Martinez-Barbera, Juan Pedro; Ruddle, Piers; Hurst, Jane; Collin, J Richard O; Salt, Alison; Cooper, Simon T; Thompson, Pamela J; Sisodiya, Sanjay M; Williamson, Kathleen A; Fitzpatrick, David R; van Heyningen, Veronica; Hanson, Isabel M

    2005-06-01

    Major malformations of the human eye, including microphthalmia and anophthalmia, are examples of phenotypes that recur in families yet often show no clear Mendelian inheritance pattern. Defining loci by mapping is therefore rarely feasible. Using a candidate-gene approach, we have identified heterozygous coding-region changes in the homeobox gene OTX2 in eight families with ocular malformations. The expression pattern of OTX2 in human embryos is consistent with the eye phenotypes observed in the patients, which range from bilateral anophthalmia to retinal defects resembling Leber congenital amaurosis and pigmentary retinopathy. Magnetic resonance imaging scans revealed defects of the optic nerve, optic chiasm, and, in some cases, brain. In two families, the mutations appear to have occurred de novo in severely affected offspring, and, in two other families, the mutations have been inherited from a gonosomal mosaic parent. Data from these four families support a simple model in which OTX2 heterozygous loss-of-function mutations cause ocular malformations. Four additional families display complex inheritance patterns, suggesting that OTX2 mutations alone may not lead to consistent phenotypes. The high incidence of mosaicism and the reduced penetrance have implications for genetic counseling.

  20. MASA syndrome is caused by mutations in the neural cell adhesion gene, L1CAM

    SciTech Connect

    Schwartz, C.E.; Wang, Y.; Schroer, R.J.; Stevenson, R.E.

    1994-09-01

    The MASA syndrome is a recessive X-linked disorder characterized by Mental retardation, Adducted thumbs, Shuffling gait and Aphasia. Recently we found that MASA in one family was likely caused by a point mutation in exon 6 of the L1CAM gene. This gene has also been shown to be involved in X-linked hydrocephalus (HSAS). We have screened 60 patients with either sporadic HSAS or MASA as well as two additional families with MASA. For the screening, we initially utilized 3 cDNA probes for the L1CAM gene. In one of the MASA families, K8310, two affected males were found to have an altered BglII band. The band was present in their carrier mother but not in their normal brothers. This band was detected by the entire cDNA probe as well as the cDNA probe for 3{prime} end of the gene. Analysis of the L1CAM sequence indicated the altered BglII site is distal to the exon 28 but proximal to the punative poly A signal site. It is hypothesized that this point mutation alters the stability of the L1CAM mRNA. This is being tested using cell lines established from the two affected males.

  1. Structural basis for early-onset neurological disorders caused by mutations in human selenocysteine synthase

    PubMed Central

    Puppala, Anupama K.; French, Rachel L.; Matthies, Doreen; Baxa, Ulrich; Subramaniam, Sriram; Simonović, Miljan

    2016-01-01

    Selenocysteine synthase (SepSecS) catalyzes the terminal reaction of selenocysteine, and is vital for human selenoproteome integrity. Autosomal recessive inheritance of mutations in SepSecS–Ala239Thr, Thr325Ser, Tyr334Cys and Tyr429*–induced severe, early-onset, neurological disorders in distinct human populations. Although harboring different mutant alleles, patients presented remarkably similar phenotypes typified by cerebellar and cerebral atrophy, seizures, irritability, ataxia, and extreme spasticity. However, it has remained unclear how these genetic alterations affected the structure of SepSecS and subsequently elicited the development of a neurological pathology. Herein, our biophysical and structural characterization demonstrates that, with the exception of Tyr429*, pathogenic mutations decrease protein stability and trigger protein misfolding. We propose that the reduced stability and increased propensity towards misfolding are the main causes for the loss of SepSecS activity in afflicted patients, and that these factors contribute to disease progression. We also suggest that misfolding of enzymes regulating protein synthesis should be considered in the diagnosis and study of childhood neurological disorders. PMID:27576344

  2. Manitoba-oculo-tricho-anal (MOTA) syndrome is caused by mutations in FREM1

    PubMed Central

    Slavotinek, Anne M; Baranzini, Sergio E; Schanze, Denny; Labelle-Dumais, Cassandre; Short, Kieran M; Chao, Ryan; Yahyavi, Mani; Bijlsma, Emilia K; Chu, Catherine; Musone, Stacey; Wheatley, Ashleigh; Kwok, Pui-Yan; Marles, Sandra; Fryns, Jean-Pierre; Maga, A Murat; Hassan, Mohamed G; Gould, Douglas B; Madireddy, Lohith; Li, Chumei; Cox, Timothy C; Smyth, Ian; Chudley, Albert E; Zenker, Martin

    2014-01-01

    Background Manitoba-oculo-tricho-anal (MOTA) syndrome is a rare condition defined by eyelid colobomas, cryptophthalmos and anophthalmia/ microphthalmia, an aberrant hairline, a bifid or broad nasal tip, and gastrointestinal anomalies such as omphalocele and anal stenosis. Autosomal recessive inheritance had been assumed because of consanguinity in the Oji-Cre population of Manitoba and reports of affected siblings, but no locus or cytogenetic aberration had previously been described. Methods and results This study shows that MOTA syndrome is caused by mutations in FREM1, a gene previously mutated in bifid nose, renal agenesis, and anorectal malformations (BNAR) syndrome. MOTA syndrome and BNAR syndrome can therefore be considered as part of a phenotypic spectrum that is similar to, but distinct from and less severe than, Fraser syndrome. Re-examination of Frem1bat/bat mutant mice found new evidence that Frem1 is involved in anal and craniofacial development, with anal prolapse, eyelid colobomas, telecanthus, a shortened snout and reduced philtral height present in the mutant mice, similar to the human phenotype in MOTA syndrome. Conclusions The milder phenotypes associated with FREM1 deficiency in humans (MOTA syndrome and BNAR syndrome) compared to that resulting from FRAS1 and FREM2 loss of function (Fraser syndrome) are also consistent with the less severe phenotypes resulting from Frem1 loss of function in mice. Together, Fraser, BNAR and MOTA syndromes constitute a clinically overlapping group of FRAS–FREM complex diseases. PMID:21507892

  3. NEK1 mutations cause short-rib polydactyly syndrome type majewski.

    PubMed

    Thiel, Christian; Kessler, Kristin; Giessl, Andreas; Dimmler, Arno; Shalev, Stavit A; von der Haar, Sigrun; Zenker, Martin; Zahnleiter, Diana; Stöss, Hartmut; Beinder, Ernst; Abou Jamra, Rami; Ekici, Arif B; Schröder-Kress, Nadja; Aigner, Thomas; Kirchner, Thomas; Reis, André; Brandstätter, Johann H; Rauch, Anita

    2011-01-01

    Defects of ciliogenesis have been implicated in a wide range of human phenotypes and play a crucial role in signal transduction and cell-cycle coordination. We used homozygosity mapping in two families with autosomal-recessive short-rib polydactyly syndrome Majewski type to identify mutations in NEK1 as an underlying cause of this lethal osteochondrodysplasia. NEK1 encodes a serine/threonine kinase with proposed function in DNA double-strand repair, neuronal development, and coordination of cell-cycle-associated ciliogenesis. We found that absence of functional full-length NEK1 severely reduces cilia number and alters ciliar morphology in vivo. We further substantiate a proposed digenic diallelic inheritance of ciliopathies by the identification of heterozygous mutations in NEK1 and DYNC2H1 in an additional family. Notably, these findings not only increase the broad spectrum of ciliar disorders, but suggest a correlation between the degree of defective microtubule or centriole elongation and organization and the severity of the resulting phenotype.

  4. Structural basis for early-onset neurological disorders caused by mutations in human selenocysteine synthase.

    PubMed

    Puppala, Anupama K; French, Rachel L; Matthies, Doreen; Baxa, Ulrich; Subramaniam, Sriram; Simonović, Miljan

    2016-01-01

    Selenocysteine synthase (SepSecS) catalyzes the terminal reaction of selenocysteine, and is vital for human selenoproteome integrity. Autosomal recessive inheritance of mutations in SepSecS-Ala239Thr, Thr325Ser, Tyr334Cys and Tyr429*-induced severe, early-onset, neurological disorders in distinct human populations. Although harboring different mutant alleles, patients presented remarkably similar phenotypes typified by cerebellar and cerebral atrophy, seizures, irritability, ataxia, and extreme spasticity. However, it has remained unclear how these genetic alterations affected the structure of SepSecS and subsequently elicited the development of a neurological pathology. Herein, our biophysical and structural characterization demonstrates that, with the exception of Tyr429*, pathogenic mutations decrease protein stability and trigger protein misfolding. We propose that the reduced stability and increased propensity towards misfolding are the main causes for the loss of SepSecS activity in afflicted patients, and that these factors contribute to disease progression. We also suggest that misfolding of enzymes regulating protein synthesis should be considered in the diagnosis and study of childhood neurological disorders. PMID:27576344

  5. Neu-Laxova syndrome, an inborn error of serine metabolism, is caused by mutations in PHGDH.

    PubMed

    Shaheen, Ranad; Rahbeeni, Zuhair; Alhashem, Amal; Faqeih, Eissa; Zhao, Qi; Xiong, Yong; Almoisheer, Agaadir; Al-Qattan, Sarah M; Almadani, Halima A; Al-Onazi, Noufa; Al-Baqawi, Badi S; Saleh, Mohammad Ali; Alkuraya, Fowzan S

    2014-06-01

    Neu-Laxova syndrome (NLS) is a rare autosomal-recessive disorder characterized by severe fetal growth restriction, microcephaly, a distinct facial appearance, ichthyosis, skeletal anomalies, and perinatal lethality. The pathogenesis of NLS remains unclear despite extensive clinical and pathological phenotyping of the >70 affected individuals reported to date, emphasizing the need to identify the underlying genetic etiology, which remains unknown. In order to identify the cause of NLS, we conducted a positional-mapping study combining autozygosity mapping and whole-exome sequencing in three consanguineous families affected by NLS. Surprisingly, the NLS-associated locus identified in this study was solved at the gene level to reveal mutations in PHGDH, which is known to be mutated in individuals with microcephaly and developmental delay. PHGDH encodes the first enzyme in the phosphorylated pathway of de novo serine synthesis, and complete deficiency of its mouse ortholog recapitulates many of the key features of NLS. This study shows that NLS represents the extreme end of a known inborn error of serine metabolism and highlights the power of genomic sequencing in revealing the unsuspected allelic nature of apparently distinct clinical entities. PMID:24836451

  6. Mutations in PADI6 Cause Female Infertility Characterized by Early Embryonic Arrest.

    PubMed

    Xu, Yao; Shi, Yingli; Fu, Jing; Yu, Min; Feng, Ruizhi; Sang, Qing; Liang, Bo; Chen, Biaobang; Qu, Ronggui; Li, Bin; Yan, Zheng; Mao, Xiaoyan; Kuang, Yanping; Jin, Li; He, Lin; Sun, Xiaoxi; Wang, Lei

    2016-09-01

    Early embryonic arrest is one of the major causes of female infertility. However, because of difficulties in phenotypic evaluation, genetic determinants of human early embryonic arrest are largely unknown. With the development of assisted reproductive technology, the phenotype of early human embryonic arrest can now be carefully evaluated. Here, we describe a consanguineous family with a recessive inheritance pattern of female infertility characterized by recurrent early embryonic arrest in cycles of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). We have identified a homozygous PADI6 nonsense mutation (c.1141C>T [p.Gln381(∗)]) that is responsible for the phenotype. Mutational analysis of PADI6 in a cohort of 36 individuals whose embryos displayed developmental arrest identified two affected individuals with compound-heterozygous mutations (c.2009_2010del [p.Glu670Glyfs(∗)48] and c.633T>A [p.His211Gln]; c.1618G>A [p.Gly540Arg] and c.970C>T [p.Gln324(∗)]). Immunostaining indicated a lack of PADI6 in affected individuals' oocytes. In addition, the amount of phosphorylated RNA polymerase II and expression levels of seven genes involved in zygotic genome activation were reduced in the affected individuals' embryos. This phenotype is consistent with Padi6 knockout mice. These findings deepen our understanding of the genetic basis of human early embryonic arrest, which has been a largely ignored Mendelian phenotype. Our findings lay the foundation for uncovering other genetic causes of infertility resulting from early embryonic arrest. PMID:27545678

  7. CSB-PGBD3 Mutations Cause Premature Ovarian Failure

    PubMed Central

    Li, Guangyu; Tang, Tie-Shan; Zhao, Shidou; Jiao, Xue; Gong, Juanjuan; Gao, Fei; Guo, Caixia; Simpson, Joe Leigh; Chen, Zi-Jiang

    2015-01-01

    Premature ovarian failure (POF) is a rare, heterogeneous disorder characterized by cessation of menstruation occurring before the age of 40 years. Genetic etiology is responsible for perhaps 25% of cases, but most cases are sporadic and unexplained. In this study, through whole exome sequencing in a non-consanguineous family having four affected members with POF and Sanger sequencing in 432 sporadic cases, we identified three novel mutations in the fusion gene CSB-PGBD3. Subsequently functional studies suggest that mutated CSB-PGBD3 fusion protein was impaired in response to DNA damage, as indicated by delayed or absent recruitment to damaged sites. Our data provide the first evidence that mutations in the CSB-PGBD3 fusion protein can cause human disease, even in the presence of functional CSB, thus potentially explaining conservation of the fusion protein for 43 My since marmoset. The localization of the CSB-PGBD3 fusion protein to UVA-induced nuclear DNA repair foci further suggests that the CSB-PGBD3 fusion protein, like many other proteins that can cause POF, modulates or participates in DNA repair. PMID:26218421

  8. CSB-PGBD3 Mutations Cause Premature Ovarian Failure.

    PubMed

    Qin, Yingying; Guo, Ting; Li, Guangyu; Tang, Tie-Shan; Zhao, Shidou; Jiao, Xue; Gong, Juanjuan; Gao, Fei; Guo, Caixia; Simpson, Joe Leigh; Chen, Zi-Jiang

    2015-07-01

    Premature ovarian failure (POF) is a rare, heterogeneous disorder characterized by cessation of menstruation occurring before the age of 40 years. Genetic etiology is responsible for perhaps 25% of cases, but most cases are sporadic and unexplained. In this study, through whole exome sequencing in a non-consanguineous family having four affected members with POF and Sanger sequencing in 432 sporadic cases, we identified three novel mutations in the fusion gene CSB-PGBD3. Subsequently functional studies suggest that mutated CSB-PGBD3 fusion protein was impaired in response to DNA damage, as indicated by delayed or absent recruitment to damaged sites. Our data provide the first evidence that mutations in the CSB-PGBD3 fusion protein can cause human disease, even in the presence of functional CSB, thus potentially explaining conservation of the fusion protein for 43 My since marmoset. The localization of the CSB-PGBD3 fusion protein to UVA-induced nuclear DNA repair foci further suggests that the CSB-PGBD3 fusion protein, like many other proteins that can cause POF, modulates or participates in DNA repair. PMID:26218421

  9. Filamin A mutation is one cause of FG syndrome.

    PubMed

    Unger, Sheila; Mainberger, Anita; Spitz, Christian; Bähr, Anna; Zeschnigk, Christine; Zabel, Bernhard; Superti-Furga, Andrea; Morris-Rosendahl, Deborah J

    2007-08-15

    FG syndrome was originally described as a rare syndromic cause of X-linked mental retardation associated with congenital heart disease, anal atresia, inguinal hernia, cryptorchidism, and other anomalies. However, recent reports have highlighted the more common milder presentation which has for cardinal features developmental delay, particularly in speech, neonatal hypotonia, relative macrocephaly, dysmorphic facial features, severe constipation, and few if any congenital malformations. Thus far, five separate loci have been identified on the X chromosome but attempts at finding the responsible gene have not yet been successful. Given that one putative FG locus (FGS2) is situated at Xq28, which is the location of the Filamin A gene (FLNA), and that a Filamin A mutation was reported in a boy with facial dysmorphism and constipation, it was hypothesized that Filamin A mutations could be one cause of FG syndrome. Indeed, a previously unreported FLNA missense mutation (P1291L) was detected in our patient with FG syndrome, thus supporting this hypothesis and indicating that FG syndrome could now be added to the list of Filamin A-related disorders. Filamin A studies in other children with FG syndrome would help to confirm this association. PMID:17632775

  10. Long-term treatment outcome of two patients with pyridoxine-dependent epilepsy caused by ALDH7A1 mutations: normal neurocognitive outcome.

    PubMed

    Nasr, Enas; Mamak, Eva; Feigenbaum, Anette; Donner, Elizabeth J; Mercimek-Mahmutoglu, Saadet

    2015-04-01

    Pyridoxine-dependent epilepsy is an autosomal recessively inherited disorder of lysine catabolism caused by mutations in the ALDH7A1 gene. We report 2 patients with normal neurocognitive outcome (full-scale IQ of 108 and 74) and their more than 10 years' treatment outcome on pyridoxine monotherapy. Both patients had specific borderline impairments in visual processing speed. More long-term treatment outcome reports will increase our knowledge about the natural history of the disease. PMID:24789515

  11. Mutations in TUBGCP4 Alter Microtubule Organization via the γ-Tubulin Ring Complex in Autosomal-Recessive Microcephaly with Chorioretinopathy

    PubMed Central

    Scheidecker, Sophie; Etard, Christelle; Haren, Laurence; Stoetzel, Corinne; Hull, Sarah; Arno, Gavin; Plagnol, Vincent; Drunat, Séverine; Passemard, Sandrine; Toutain, Annick; Obringer, Cathy; Koob, Mériam; Geoffroy, Véronique; Marion, Vincent; Strähle, Uwe; Ostergaard, Pia; Verloes, Alain; Merdes, Andreas; Moore, Anthony T.; Dollfus, Hélène

    2015-01-01

    We have identified TUBGCP4 variants in individuals with autosomal-recessive microcephaly and chorioretinopathy. Whole-exome sequencing performed on one family with two affected siblings and independently on another family with one affected child revealed compound-heterozygous mutations in TUBGCP4. Subsequent Sanger sequencing was performed on a panel of individuals from 12 French families affected by microcephaly and ophthalmic manifestations, and one other individual was identified with compound-heterozygous mutations in TUBGCP4. One synonymous variant was common to all three families and was shown to induce exon skipping; the other mutations were frameshift mutations and a deletion. TUBGCP4 encodes γ-tubulin complex protein 4, a component belonging to the γ-tubulin ring complex (γ-TuRC) and known to regulate the nucleation and organization of microtubules. Functional analysis of individual fibroblasts disclosed reduced levels of the γ-TuRC, altered nucleation and organization of microtubules, abnormal nuclear shape, and aneuploidy. Moreover, zebrafish treated with morpholinos against tubgcp4 were found to have reduced head volume and eye developmental anomalies with chorioretinal dysplasia. In summary, the identification of TUBGCP4 mutations in individuals with microcephaly and a spectrum of anomalies in eye development, particularly photoreceptor anomalies, provides evidence of an important role for the γ-TuRC in brain and eye development. PMID:25817018

  12. Mutations in TUBB8 cause human oocyte meiotic arrest

    PubMed Central

    Feng, Ruizhi; Sang, Qing; Kuang, Yanping; Sun, Xiaoxi; Yan, Zheng; Zhang, Shaozhen; Shi, Juanzi; Tian, Guoling; Luchniak, Anna; Fukuda, Yusuke; Li, Bin; Yu, Min; Chen, Junling; Xu, Yao; Guo, Luo; Qu, Ronggui; Wang, Xueqian; Sun, Zhaogui; Liu, Miao; Shi, Huijuan; Wang, Hongyan; Feng, Yi; Shao, Ruijin; Chai, Renjie; Li, Qiaoli; Xing, Qinghe; Zhang, Rui; Nogales, Eva; Jin, Li; He, Lin; Gupta, Mohan L.; Cowan, Nicholas J.; Wang, Lei

    2016-01-01

    Background Successful human reproduction depends on the fusion of a mature oocyte with a sperm cell to form a fertilized egg. The genetic events that lead to human oocyte maturation arrest are unknown. Methods We recruited a rare four-generation family with female infertility as a consequence of oocyte meiosis I arrest. We applied whole-exome and direct Sanger sequencing to an additional 23 patients following identification of mutations in a candidate gene, TUBB8. Expression of TUBB8 and all other β-tubulin isotypes was measured in human oocytes, early embryos, sperm cells and several somatic tissues by qRT-PCR. The effect of the TUBB8 mutations was assessed on α/β tubulin heterodimer assembly in vitro, on microtubule architecture in HeLa cells, on microtubule dynamics in yeast cells, and on spindle assembly in mouse and human oocytes via microinjection of the corresponding cRNAs. Results We identified seven mutations in the primate-specific gene TUBB8 that are responsible for human oocyte meiosis I arrest in seven families. TUBB8 expression is unique to oocytes and the early embryo, where this gene accounts for almost all of the expressed β-tubulin. The mutations affect the chaperone-dependent folding and assembly of the α/β-tubulin heterodimer, induce microtubule chaos upon expression in cultured cells, alter microtubule dynamics in vivo, and cause catastrophic spindle assembly defects and maturation arrest upon expression in mouse and human oocytes. Conclusions TUBB8 mutations function via dominant negative effects that massively disrupt proper microtubule behavior. TUBB8 is a key gene involved in human oocyte meiotic spindle assembly and maturation. PMID:26789871

  13. Mutations in ALDH1A3 cause microphthalmia.

    PubMed

    Aldahmesh, M A; Khan, A O; Hijazi, H; Alkuraya, F S

    2013-08-01

    Microphthalmia is an important inborn error of eye development that can be associated with multisystem involvement. Anophthalmia is more severe and rarer. Single mutations in an expanding list of genes are known to cause this spectrum of anomaly. In one branch of a multiplex family with microphthalmia and anophthalmia, autozygome analysis excluded all known microphthalmia genes at the time of doing this study. Exome sequencing and autozygome filtration identified a novel homozygous variant in ALDH1A3. Subsequently, we identified another homozygous variant in 2 of the 10 probands with microphthalmia we specifically screened for mutations in ALDH1A3. Interestingly, the other branch of the original family was found to segregate anophthalmia/syndactyly with a novel homozygous SMOC1 variant. Our data support the very recent and independent identification of ALDH1A3 as a disease gene in microphthalmia. Locus heterogeneity should be considered in consanguineous families even for extremely rare phenotypes.

  14. Mutations in KPTN cause macrocephaly, neurodevelopmental delay, and seizures.

    PubMed

    Baple, Emma L; Maroofian, Reza; Chioza, Barry A; Izadi, Maryam; Cross, Harold E; Al-Turki, Saeed; Barwick, Katy; Skrzypiec, Anna; Pawlak, Robert; Wagner, Karin; Coblentz, Roselyn; Zainy, Tala; Patton, Michael A; Mansour, Sahar; Rich, Phillip; Qualmann, Britta; Hurles, Matt E; Kessels, Michael M; Crosby, Andrew H

    2014-01-01

    The proper development of neuronal circuits during neuromorphogenesis and neuronal-network formation is critically dependent on a coordinated and intricate series of molecular and cellular cues and responses. Although the cortical actin cytoskeleton is known to play a key role in neuromorphogenesis, relatively little is known about the specific molecules important for this process. Using linkage analysis and whole-exome sequencing on samples from families from the Amish community of Ohio, we have demonstrated that mutations in KPTN, encoding kaptin, cause a syndrome typified by macrocephaly, neurodevelopmental delay, and seizures. Our immunofluorescence analyses in primary neuronal cell cultures showed that endogenous and GFP-tagged kaptin associates with dynamic actin cytoskeletal structures and that this association is lost upon introduction of the identified mutations. Taken together, our studies have identified kaptin alterations responsible for macrocephaly and neurodevelopmental delay and define kaptin as a molecule crucial for normal human neuromorphogenesis. PMID:24239382

  15. Mutations in KPTN Cause Macrocephaly, Neurodevelopmental Delay, and Seizures

    PubMed Central

    Baple, Emma L.; Maroofian, Reza; Chioza, Barry A.; Izadi, Maryam; Cross, Harold E.; Al-Turki, Saeed; Barwick, Katy; Skrzypiec, Anna; Pawlak, Robert; Wagner, Karin; Coblentz, Roselyn; Zainy, Tala; Patton, Michael A.; Mansour, Sahar; Rich, Phillip; Qualmann, Britta; Hurles, Matt E.; Kessels, Michael M.; Crosby, Andrew H.

    2014-01-01

    The proper development of neuronal circuits during neuromorphogenesis and neuronal-network formation is critically dependent on a coordinated and intricate series of molecular and cellular cues and responses. Although the cortical actin cytoskeleton is known to play a key role in neuromorphogenesis, relatively little is known about the specific molecules important for this process. Using linkage analysis and whole-exome sequencing on samples from families from the Amish community of Ohio, we have demonstrated that mutations in KPTN, encoding kaptin, cause a syndrome typified by macrocephaly, neurodevelopmental delay, and seizures. Our immunofluorescence analyses in primary neuronal cell cultures showed that endogenous and GFP-tagged kaptin associates with dynamic actin cytoskeletal structures and that this association is lost upon introduction of the identified mutations. Taken together, our studies have identified kaptin alterations responsible for macrocephaly and neurodevelopmental delay and define kaptin as a molecule crucial for normal human neuromorphogenesis. PMID:24239382

  16. Diseases caused by mutations in ORAI1 and STIM1

    PubMed Central

    Lacruz, Rodrigo S.; Feske, Stefan

    2015-01-01

    Ca2+ release-activated Ca2+ (CRAC) channels mediate a specific form of Ca2+ influx called store-operated Ca2+ entry (SOCE) that contributes to the function of many cell types. CRAC channels are formed by ORAI1 proteins located in the plasma membrane, which form its ion-conducting pore. ORAI1 channels are activated by stromal interaction molecule (STIM) 1 and STIM2 located in the endoplasmic reticulum. Loss- and gain-of-function gene mutations in ORAI1 and STIM1 in human patients cause distinct disease syndromes. CRAC channelopathy is caused by loss-of-function mutations in ORAI1 and STIM1 that abolish CRAC channel function and SOCE; it is characterized by severe combined immunodeficiency (SCID)-like disease, autoimmunity, muscular hypotonia, and ectodermal dysplasia, with defects in dental enamel. The latter defect emphasizes an important role of CRAC channels in tooth development. By contrast, autosomal dominant gain-of-function mutations in these genes result in constitutive CRAC channel activation, SOCE, and increased intracellular Ca2+ levels that are associated with an overlapping spectrum of diseases, including non-syndromic tubular aggregate myopathy (TAM) and York platelet and Stormorken syndromes, two syndromes defined, besides myopathy, by thrombocytopenia, thrombopathy, and bleeding diathesis. The fact that myopathy results from loss- and gain-of-function mutations in ORAI1 and STIM1 highlights the importance of CRAC channels for Ca2+ homeostasis in skeletal muscle function. The cellular dysfunction and clinical disease spectrum observed in mutant patients provide important information about the molecular regulation of ORAI1 and STIM1 proteins and the role of CRAC channels in human physiology. PMID:26469693

  17. What Is a Recessive Allele?

    ERIC Educational Resources Information Center

    American Biology Teacher, 1991

    1991-01-01

    Presents four misconceptions students have concerning the concepts of recessive and dominant alleles. Discusses the spectrum of dominant-recessive relationships, different levels of analysis between phenotype and genotype, possible causes of dominance, and an example involving wrinkled peas. (MDH)

  18. Mutation of kri1l causes definitive hematopoiesis failure via PERK-dependent excessive autophagy induction

    PubMed Central

    Jia, Xiao-E; Ma, Ke; Xu, Tao; Gao, Lei; Wu, Shuang; Fu, Cong; Zhang, Wenjuan; Wang, Zhizhang; Liu, Kaiyu; Dong, Mei; Jing, Changbin; Ren, Chunguang; Dong, Zhiwei; Chen, Yi; Jin, Yi; Huang, Qiuhua; Chang, Xing; Deng, Min; Li, Li; Luo, Lingfei; Zhu, Jun; Dang, Yongjun; Chang, Hung-Chun; Zon, Leonard I; Zhou, Yi; Chen, Saijuan; Pan, Weijun

    2015-01-01

    Dysregulation of ribosome biogenesis causes human diseases, such as Diamond-Blackfan anemia, del (5q-) syndrome and bone marrow failure. However, the mechanisms of blood disorders in these diseases remain elusive. Through genetic mapping, molecular cloning and mechanism characterization of the zebrafish mutant cas002, we reveal a novel connection between ribosomal dysfunction and excessive autophagy in the regulation of hematopoietic stem/progenitor cells (HSPCs). cas002 carries a recessive lethal mutation in kri1l gene that encodes an essential component of rRNA small subunit processome. We show that Kri1l is required for normal ribosome biogenesis, expansion of definitive HSPCs and subsequent lineage differentiation. Through live imaging and biochemical studies, we find that loss of Kri1l causes the accumulation of misfolded proteins and excessive PERK activation-dependent autophagy in HSPCs. Blocking autophagy but not inhibiting apoptosis by Bcl2 overexpression can fully rescue hematopoietic defects, but not the lethality of kri1lcas002 embryos. Treatment with autophagy inhibitors (3-MA and Baf A1) or PERK inhibitor (GSK2656157), or knockdown of beclin1 or perk can markedly restore HSPC proliferation and definitive hematopoietic cell differentiation. These results may provide leads for effective therapeutics that benefit patients with anemia or bone marrow failure caused by ribosome disorders. PMID:26138676

  19. Mutation of kri1l causes definitive hematopoiesis failure via PERK-dependent excessive autophagy induction.

    PubMed

    Jia, Xiao-E; Ma, Ke; Xu, Tao; Gao, Lei; Wu, Shuang; Fu, Cong; Zhang, Wenjuan; Wang, Zhizhang; Liu, Kaiyu; Dong, Mei; Jing, Changbin; Ren, Chunguang; Dong, Zhiwei; Chen, Yi; Jin, Yi; Huang, Qiuhua; Chang, Xing; Deng, Min; Li, Li; Luo, Lingfei; Zhu, Jun; Dang, Yongjun; Chang, Hung-Chun; Zon, Leonard I; Zhou, Yi; Chen, Saijuan; Pan, Weijun

    2015-08-01

    Dysregulation of ribosome biogenesis causes human diseases, such as Diamond-Blackfan anemia, del (5q-) syndrome and bone marrow failure. However, the mechanisms of blood disorders in these diseases remain elusive. Through genetic mapping, molecular cloning and mechanism characterization of the zebrafish mutant cas002, we reveal a novel connection between ribosomal dysfunction and excessive autophagy in the regulation of hematopoietic stem/progenitor cells (HSPCs). cas002 carries a recessive lethal mutation in kri1l gene that encodes an essential component of rRNA small subunit processome. We show that Kri1l is required for normal ribosome biogenesis, expansion of definitive HSPCs and subsequent lineage differentiation. Through live imaging and biochemical studies, we find that loss of Kri1l causes the accumulation of misfolded proteins and excessive PERK activation-dependent autophagy in HSPCs. Blocking autophagy but not inhibiting apoptosis by Bcl2 overexpression can fully rescue hematopoietic defects, but not the lethality of kri1l(cas002) embryos. Treatment with autophagy inhibitors (3-MA and Baf A1) or PERK inhibitor (GSK2656157), or knockdown of beclin1 or perk can markedly restore HSPC proliferation and definitive hematopoietic cell differentiation. These results may provide leads for effective therapeutics that benefit patients with anemia or bone marrow failure caused by ribosome disorders.

  20. Mutation of kri1l causes definitive hematopoiesis failure via PERK-dependent excessive autophagy induction.

    PubMed

    Jia, Xiao-E; Ma, Ke; Xu, Tao; Gao, Lei; Wu, Shuang; Fu, Cong; Zhang, Wenjuan; Wang, Zhizhang; Liu, Kaiyu; Dong, Mei; Jing, Changbin; Ren, Chunguang; Dong, Zhiwei; Chen, Yi; Jin, Yi; Huang, Qiuhua; Chang, Xing; Deng, Min; Li, Li; Luo, Lingfei; Zhu, Jun; Dang, Yongjun; Chang, Hung-Chun; Zon, Leonard I; Zhou, Yi; Chen, Saijuan; Pan, Weijun

    2015-08-01

    Dysregulation of ribosome biogenesis causes human diseases, such as Diamond-Blackfan anemia, del (5q-) syndrome and bone marrow failure. However, the mechanisms of blood disorders in these diseases remain elusive. Through genetic mapping, molecular cloning and mechanism characterization of the zebrafish mutant cas002, we reveal a novel connection between ribosomal dysfunction and excessive autophagy in the regulation of hematopoietic stem/progenitor cells (HSPCs). cas002 carries a recessive lethal mutation in kri1l gene that encodes an essential component of rRNA small subunit processome. We show that Kri1l is required for normal ribosome biogenesis, expansion of definitive HSPCs and subsequent lineage differentiation. Through live imaging and biochemical studies, we find that loss of Kri1l causes the accumulation of misfolded proteins and excessive PERK activation-dependent autophagy in HSPCs. Blocking autophagy but not inhibiting apoptosis by Bcl2 overexpression can fully rescue hematopoietic defects, but not the lethality of kri1l(cas002) embryos. Treatment with autophagy inhibitors (3-MA and Baf A1) or PERK inhibitor (GSK2656157), or knockdown of beclin1 or perk can markedly restore HSPC proliferation and definitive hematopoietic cell differentiation. These results may provide leads for effective therapeutics that benefit patients with anemia or bone marrow failure caused by ribosome disorders. PMID:26138676

  1. As little as needed: the extraordinary case of a mild recessive osteopetrosis owing to a novel splicing hypomorphic mutation in the TCIRG1 gene.

    PubMed

    Sobacchi, Cristina; Pangrazio, Alessandra; Lopez, Antonio González-Meneses; Gomez, Diego Pascual-Vaca; Caldana, Maria Elena; Susani, Lucia; Vezzoni, Paolo; Villa, Anna

    2014-07-01

    Mutations in the TCIRG1 gene, coding for a subunit of the osteoclast proton pump, are responsible for more than 50% of cases of human malignant autosomal recessive osteopetrosis (ARO), a rare inherited bone disease with increased bone density owing to a failure in bone resorption. A wide variety of mutations has been described, including missense, nonsense, small deletions/insertions, splice-site mutations, and large genomic deletions, all leading to a similar severe presentation. So far, to the best of our knowledge, no report of a mild phenotype owing to recessive TCIRG1 mutations is present neither in our series of more than 100 TCIRG1-dependent ARO patients nor in the literature. Here we describe an 8-year-old patient referred to us with a clinical diagnosis of ARO, based on radiological findings; of note, no neurological or hematological defects were present in this girl. Surprisingly, we identified a novel nucleotide change in intron 15 of the TCIRG1 gene at the homozygous state, leading to the production of multiple aberrant transcripts, but also, more importantly, of a limited amount of the normal transcript. Our results show that a low level of normal TCIRG1 protein can dampen the clinical presentation of TCIRG1-dependent ARO. On this basis, a small amount of protein might be sufficient to rescue, at least partially, the severe ARO phenotype, and this is particularly important when gene therapy approaches are considered. In addition, we would also recommend that the TCIRG1 gene be included in the molecular diagnosis of mild forms of human ARO.

  2. Myelin-associated glycoprotein gene mutation causes Pelizaeus-Merzbacher disease-like disorder

    PubMed Central

    Elazar, Nimrod; Lerer, Israela; Schueler-Furman, Ora; Fellig, Yakov; Glick, Benjamin; Zimmerman, Bat-El; Azulay, Haim; Dotan, Shlomo; Goldberg, Sharon; Gomori, John M.; Ponger, Penina; Newman, J. P.; Marreed, Hodaifah; Steck, Andreas J.; Schaeren-Wiemers, Nicole; Mor, Nofar; Harel, Michal; Geiger, Tamar; Eshed-Eisenbach, Yael; Peles, Elior

    2015-01-01

    Pelizaeus-Merzbacher disease is an X-linked hypomyelinating leukodystrophy caused by mutations or rearrangements in PLP1. It presents in infancy with nystagmus, jerky head movements, hypotonia and developmental delay evolving into spastic tetraplegia with optic atrophy and variable movement disorders. A clinically similar phenotype caused by recessive mutations in GJC2 is known as Pelizaeus-Merzbacher-like disease. Both genes encode proteins associated with myelin. We describe three siblings of a consanguineous family manifesting the typical infantile-onset Pelizaeus-Merzbacher disease-like phenotype slowly evolving into a form of complicated hereditary spastic paraplegia with mental retardation, dysarthria, optic atrophy and peripheral neuropathy in adulthood. Magnetic resonance imaging and spectroscopy were consistent with a demyelinating leukodystrophy. Using genetic linkage and exome sequencing, we identified a homozygous missense c.399C>G; p.S133R mutation in MAG. This gene, previously associated with hereditary spastic paraplegia, encodes myelin-associated glycoprotein, which is involved in myelin maintenance and glia-axon interaction. This mutation is predicted to destabilize the protein and affect its tertiary structure. Examination of the sural nerve biopsy sample obtained in childhood in the oldest sibling revealed complete absence of myelin-associated glycoprotein accompanied by ill-formed onion-bulb structures and a relatively thin myelin sheath of the affected axons. Immunofluorescence, cell surface labelling, biochemical analysis and mass spectrometry-based proteomics studies in a variety of cell types demonstrated a devastating effect of the mutation on post-translational processing, steady state expression and subcellular localization of myelin-associated glycoprotein. In contrast to the wild-type protein, the p.S133R mutant was retained in the endoplasmic reticulum and was subjected to endoplasmic reticulum-associated protein degradation by the

  3. Mutations in STIL, encoding a pericentriolar and centrosomal protein, cause primary microcephaly.

    PubMed

    Kumar, Arun; Girimaji, Satish C; Duvvari, Mahesh R; Blanton, Susan H

    2009-02-01

    Primary microcephaly (MCPH) is an autosomal-recessive congenital disorder characterized by smaller-than-normal brain size and mental retardation. MCPH is genetically heterogeneous with six known loci: MCPH1-MCPH6. We report mapping of a novel locus, MCPH7, to chromosome 1p32.3-p33 between markers D1S2797 and D1S417, corresponding to a physical distance of 8.39 Mb. Heterogeneity analysis of 24 families previously excluded from linkage to the six known MCPH loci suggested linkage of five families (20.83%) to the MCPH7 locus. In addition, four families were excluded from linkage to the MCPH7 locus as well as all of the six previously known loci, whereas the remaining 15 families could not be conclusively excluded or included. The combined maximum two-point LOD score for the linked families was 5.96 at marker D1S386 at theta = 0.0. The combined multipoint LOD score was 6.97 between markers D1S2797 and D1S417. Previously, mutations in four genes, MCPH1, CDK5RAP2, ASPM, and CENPJ, that code for centrosomal proteins have been shown to cause this disorder. Three different homozygous mutations in STIL, which codes for a pericentriolar and centrosomal protein, were identified in patients from three of the five families linked to the MCPH7 locus; all are predicted to truncate the STIL protein. Further, another recently ascertained family was homozygous for the same mutation as one of the original families. There was no evidence for a common haplotype. These results suggest that the centrosome and its associated structures are important in the control of neurogenesis in the developing human brain. PMID:19215732

  4. Congenital lamellar ichthyosis in Tunisia is caused by a founder nonsense mutation in the TGM1 gene.

    PubMed

    Louhichi, Nacim; Hadjsalem, Ikhlass; Marrakchi, Slaheddine; Trabelsi, Fatma; Masmoudi, Abderrahmen; Turki, Hamida; Fakhfakh, Faiza

    2013-03-01

    Lamellar ichthyosis (LI, MIM# 242300) is a severe autosomal recessive genodermatosis present at birth in the form of collodion membrane covering the neonate. Mutations in the TGM1 gene encoding transglutaminase-1 are a major cause of LI. In this study molecular analysis of two LI Tunisian patients revealed a common nonsense c.788G>A mutation in TGM1 gene. The identification of a cluster of LI pedigrees carrying the c.788G>A mutation in a specific area raises the question of the origin of this mutation from a common ancestor. We carried out a haplotype-based analysis by way of genotyping 4 microsatellite markers and 8 SNPs flanking and within the TGM1 gene spanning a region of 6 Mb. Haplotype reconstruction from genotypes of all members of the affected pedigrees indicated that all carriers for the mutation c.788G>A harbored the same haplotype, indicating common ancestor. The finding of a founder effect in a rare disease is essential for the genetic diagnosis and the genetic counselling of affected LI pedigrees in Tunisia.

  5. Pyridoxine-dependent epilepsy in Tunisia is caused by a founder missense mutation of the ALDH7A1 gene.

    PubMed

    Tlili, Abdelaziz; Hamida Hentati, Nadia; Chaabane, Rim; Gargouri, Abdellatif; Fakhfakh, Faiza

    2013-04-15

    Pyridoxine-dependent epilepsy (PDE) is a rare autosomal recessive disorder characterized by seizures and therapeutic response to pharmacological dose of pyridoxine. Mutations in the ALDH7A1 gene, encoding α-aminoadipic semialdehyde (α-AASA) dehydrogenase (antiquitin), have been reported to cause PDE in most patients. In this study molecular analysis of seven PDE Tunisian patients revealed a common missense c.1364T>C mutation in the ALDH7A1 gene. The identification of a cluster of PDE pedigrees carrying the c.1364T>C mutation in a specific area raises the question of the origin of this mutation from a common ancestor. We carried out a genotype-based analysis by way of genotyping a new generated microsatellite marker within the ALDH7A1 gene. Genotype reconstruction of all affected pedigree members indicate that all c.1364T>C mutation carriers harbored the same allele, indicating a common ancestor. The finding of a founder effect in a rare disease is essential for the genetic diagnosis and the genetic counseling of affected PDE pedigrees in Tunisia.

  6. Self-compatibility in Brassica napus is caused by independent mutations in S-locus genes.

    PubMed

    Okamoto, Shunsuke; Odashima, Masashi; Fujimoto, Ryo; Sato, Yutaka; Kitashiba, Hiroyasu; Nishio, Takeshi

    2007-05-01

    Brassica napus is an amphidiploid species with the A genome from Brassica rapa and the C genome from Brassica oleracea. Although B. rapa, B. oleracea and artificially synthesized amphidiploids with the AC genome are self-incompatible, B. napus is self-compatible. Six S genotypes were identified in B. napus, five of which had class I S haplotypes from one species and a class II S haplotype from the other species, and mutations causing self-compatibility were identified in three of these S genotypes. The most predominant S genotype (BnS-1;BnS-6), which is that of cv. 'Westar', had a class I S haplotype similar to B. rapa S-47 (BrS-47) and a class II S haplotype similar to B. oleracea S-15 (BoS-15). The stigmas of 'Westar' rejected the pollen grains of both BrS-47 and BoS-15, while reciprocal crossings were compatible. Insertion of a DNA fragment of about 3.6 kb was found in the promoter region of the SP11/SCR allele of BnS-1, and transcripts of SP11/SCR were not detected in 'Westar'. The nucleotide sequence of the SP11 genomic DNA of BnS-6 was 100% identical to that of SP11 of BoS-15. Class I SP11 alleles from one species showed dominance over class II SP11 alleles from the other species in artificially synthesized B. napus lines, suggesting that the non-functional dominant SP11 allele suppressed the expression of the recessive SP11 allele in 'Westar'. Two other S genotypes in B. napus also had non-functional class I S haplotypes together with recessive BnS-6. These observations suggest independent origins of self-compatibility in B. napus.

  7. Compound heterozygosity for a dominant glycine substitution and a recessive internal duplication mutation in the type XVII collagen gene results in junctional epidermolysis bullosa and abnormal dentition.

    PubMed

    McGrath, J A; Gatalica, B; Li, K; Dunnill, M G; McMillan, J R; Christiano, A M; Eady, R A; Uitto, J

    1996-06-01

    Junctional epidermolysis bullosa is a heterogeneous autosomal recessively inherited blistering skin disorder associated with fragility at the dermal-epidermal junction. Previously, mutations in this condition have been described in the three genes for the anchoring filament protein laminin 5 (LAMA3, LAMB3, and LAMC2), in the gene encoding the hemidesmosome-associated beta4 integrin (ITGB4), and in the gene for the hemidesmosomal protein type XVII collagen (COL17A1/BPAG2). In this study, we report a patient with a form of junctional epidermolysis bullosa with skin fragility and dental anomalies who is a compound heterozygote for a novel combination of mutations, ie, a glycine substitution mutation in one allele and an internal duplication in the other allele of COL17A1. The patient also has two offspring, both of whom have inherited the glycine substitution mutation, whereas the other COL17A1 allele is normal. The latter individuals show no evidence of skin fragility but have marked dental abnormalities with enamel hypoplasia and pitting. The clinical phenotype of junctional epidermolysis bullosa in the proband in this family probably arises due to a combination of the glycine substitution and the internal duplication in COL17A1, whereas the dental abnormalities of her offspring may be the result of the glycine substitution in COL17A1 alone, resulting in this dominantly inherited clinical phenotype. PMID:8669466

  8. Kidney adysplasia and variable hydronephrosis, a new mutation affecting the odd-skipped related 1 gene in the mouse, causes variable defects in kidney development and hydronephrosis

    PubMed Central

    Davisson, Muriel T.; Cook, Susan A.; Akeson, Ellen C.; Liu, Don; Heffner, Caleb; Gudis, Polyxeni; Fairfield, Heather

    2015-01-01

    Many genes, including odd-skipped related 1 (Osr1), are involved in regulation of mammalian kidney development. We describe here a new recessive mutation (kidney adysplasia and variable hydronephrosis, kavh) in the mouse that leads to downregulation of Osr1 transcript, causing several kidney defects: agenesis, hypoplasia, and hydronephrosis with variable age of onset. The mutation is closely associated with a reciprocal translocation, T(12;17)4Rk, whose Chromosome 12 breakpoint is upstream from Osr1. The kavh/kavh mutant provides a model to study kidney development and test therapies for hydronephrosis. PMID:25834070

  9. Kidney adysplasia and variable hydronephrosis, a new mutation affecting the odd-skipped related 1 gene in the mouse, causes variable defects in kidney development and hydronephrosis.

    PubMed

    Davisson, Muriel T; Cook, Susan A; Akeson, Ellen C; Liu, Don; Heffner, Caleb; Gudis, Polyxeni; Fairfield, Heather; Murray, Stephen A

    2015-06-15

    Many genes, including odd-skipped related 1 (Osr1), are involved in regulation of mammalian kidney development. We describe here a new recessive mutation (kidney adysplasia and variable hydronephrosis, kavh) in the mouse that leads to downregulation of Osr1 transcript, causing several kidney defects: agenesis, hypoplasia, and hydronephrosis with variable age of onset. The mutation is closely associated with a reciprocal translocation, T(12;17)4Rk, whose Chromosome 12 breakpoint is upstream from Osr1. The kavh/kavh mutant provides a model to study kidney development and test therapies for hydronephrosis.

  10. Mutations in NOTCH1 cause Adams-Oliver syndrome.

    PubMed

    Stittrich, Anna-Barbara; Lehman, Anna; Bodian, Dale L; Ashworth, Justin; Zong, Zheyuan; Li, Hong; Lam, Patricia; Khromykh, Alina; Iyer, Ramaswamy K; Vockley, Joseph G; Baveja, Rajiv; Silva, Ermelinda Santos; Dixon, Joanne; Leon, Eyby L; Solomon, Benjamin D; Glusman, Gustavo; Niederhuber, John E; Roach, Jared C; Patel, Millan S

    2014-09-01

    Notch signaling determines and reinforces cell fate in bilaterally symmetric multicellular eukaryotes. Despite the involvement of Notch in many key developmental systems, human mutations in Notch signaling components have mainly been described in disorders with vascular and bone effects. Here, we report five heterozygous NOTCH1 variants in unrelated individuals with Adams-Oliver syndrome (AOS), a rare disease with major features of aplasia cutis of the scalp and terminal transverse limb defects. Using whole-genome sequencing in a cohort of 11 families lacking mutations in the four genes with known roles in AOS pathology (ARHGAP31, RBPJ, DOCK6, and EOGT), we found a heterozygous de novo 85 kb deletion spanning the NOTCH1 5' region and three coding variants (c.1285T>C [p.Cys429Arg], c.4487G>A [p.Cys1496Tyr], and c.5965G>A [p.Asp1989Asn]), two of which are de novo, in four unrelated probands. In a fifth family, we identified a heterozygous canonical splice-site variant (c.743-1 G>T) in an affected father and daughter. These variants were not present in 5,077 in-house control genomes or in public databases. In keeping with the prominent developmental role described for Notch1 in mouse vasculature, we observed cardiac and multiple vascular defects in four of the five families. We propose that the limb and scalp defects might also be due to a vasculopathy in NOTCH1-related AOS. Our results suggest that mutations in NOTCH1 are the most common cause of AOS and add to a growing list of human diseases that have a vascular and/or bony component and are caused by alterations in the Notch signaling pathway. PMID:25132448

  11. A Nonsense Mutation in the Acid α-Glucosidase Gene Causes Pompe Disease in Finnish and Swedish Lapphunds

    PubMed Central

    Seppälä, Eija H.; Reuser, Arnold J. J.; Lohi, Hannes

    2013-01-01

    Pompe disease is a recessively inherited and often fatal disorder caused by the deficiency of acid α-glucosidase, an enzyme encoded by the GAA gene and needed to break down glycogen in lysosomes. This glycogen storage disease type II has been reported also in Swedish Lapphund dogs. Here we describe the genetic defect in canine Pompe disease and show that three related breeds from Scandinavia carry the same mutation. The affected dogs are homozygous for the GAA c.2237G>A mutation leading to a premature stop codon at amino acid position 746. The corresponding mutation has previously been reported in humans and causes infantile Pompe disease in combination with a second fully deleterious mutation. The affected dogs from both the Finnish as well as the Swedish breed mimic infantile-onset Pompe disease genetically, but also clinico-pathologically. Therefore this canine model provides a valuable tool for preclinical studies aimed at the development of gene therapy in Pompe disease. PMID:23457621

  12. Mutations in UVSSA cause UV-sensitive syndrome and destabilize ERCC6 in transcription-coupled DNA repair.

    PubMed

    Zhang, Xue; Horibata, Katsuyoshi; Saijo, Masafumi; Ishigami, Chie; Ukai, Akiko; Kanno, Shin-ichiro; Tahara, Hidetoshi; Neilan, Edward G; Honma, Masamitsu; Nohmi, Takehiko; Yasui, Akira; Tanaka, Kiyoji

    2012-05-01

    UV-sensitive syndrome (UV(S)S) is an autosomal recessive disorder characterized by photosensitivity and deficiency in transcription-coupled repair (TCR), a subpathway of nucleotide-excision repair that rapidly removes transcription-blocking DNA damage. Cockayne syndrome is a related disorder with defective TCR and consists of two complementation groups, Cockayne syndrome (CS)-A and