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Sample records for mutation causing recessive

  1. STIL mutation causes autosomal recessive microcephalic lobar holoprosencephaly.

    PubMed

    Kakar, Naseebullah; Ahmad, Jamil; Morris-Rosendahl, Deborah J; Altmüller, Janine; Friedrich, Katrin; Barbi, Gotthold; Nürnberg, Peter; Kubisch, Christian; Dobyns, William B; Borck, Guntram

    2015-01-01

    Holoprosencephaly is a clinically and genetically heterogeneous midline brain malformation associated with neurologic manifestations including developmental delay, intellectual disability and seizures. Although mutations in the sonic hedgehog gene SHH and more than 10 other genes are known to cause holoprosencephaly, many patients remain without a molecular diagnosis. Here we show that a homozygous truncating mutation of STIL not only causes severe autosomal recessive microcephaly, but also lobar holoprosencephaly in an extended consanguineous Pakistani family. STIL mutations have previously been linked to centrosomal defects in primary microcephaly at the MCPH7 locus. Our results thus expand the clinical phenotypes associated with biallellic STIL mutations to include holoprosencephaly. PMID:25218063

  2. Mutations in HPCA Cause Autosomal-Recessive Primary Isolated Dystonia

    PubMed Central

    Charlesworth, Gavin; Angelova, Plamena R.; Bartolomé-Robledo, Fernando; Ryten, Mina; Trabzuni, Daniah; Stamelou, Maria; Abramov, Andrey Y.; Bhatia, Kailash P.; Wood, Nicholas W.

    2015-01-01

    Reports of primary isolated dystonia inherited in an autosomal-recessive (AR) manner, often lumped together as “DYT2 dystonia,” have appeared in the scientific literature for several decades, but no genetic cause has been identified to date. Using a combination of homozygosity mapping and whole-exome sequencing in a consanguineous kindred affected by AR isolated dystonia, we identified homozygous mutations in HPCA, a gene encoding a neuronal calcium sensor protein found almost exclusively in the brain and at particularly high levels in the striatum, as the cause of disease in this family. Subsequently, compound-heterozygous mutations in HPCA were also identified in a second independent kindred affected by AR isolated dystonia. Functional studies suggest that hippocalcin might play a role in regulating voltage-dependent calcium channels. The identification of mutations in HPCA as a cause of AR primary isolated dystonia paves the way for further studies to assess whether “DYT2 dystonia” is a genetically homogeneous condition or not. PMID:25799108

  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. Novel recessive myotilin mutation causes severe myofibrillar myopathy.

    PubMed

    Schessl, Joachim; Bach, Elisa; Rost, Simone; Feldkirchner, Sarah; Kubny, Christiana; Müller, Stefan; Hanisch, Franz-Georg; Kress, Wolfram; Schoser, Benedikt

    2014-08-01

    We identified the first homozygous and hence recessive mutation in the myotilin gene (MYOT) in a family affected by a severe myofibrillar myopathy (MFM). MFM is a rare, progressive and devastating disease of human skeletal muscle with distinct histopathological pattern of protein aggregates and myofibrillar degeneration. So far, only heterozygous missense mutations in MYOT have been associated with autosomal dominant myofibrillar myopathy, limb-girdle muscular dystrophy type 1A and distal myopathy. Myotilin itself is highly expressed in skeletal and cardiac muscle and is localized at the Z-disc and therefore interacts in sarcomere assembly. We performed whole-exome sequencing in a German family clinically diagnosed with MFM and identified a homozygous mutation in exon 2, c.16C > G (p.Arg6Gly). Using laser microdissection followed by quantitative mass spectrometry, we identified the myotilin protein as one component showing the highest increased abundance in the aggregates in the index patient. We suggest that the combined approach has a high potential as a new tool for the confirmation of unclassified variants which are found in whole-exome sequencing approaches. PMID:24928145

  6. Mutation of TBCK causes a rare recessive developmental disorder

    PubMed Central

    Guerreiro, Rita J.; Brown, Rachel; Dian, Donnai; de Goede, Christian

    2016-01-01

    Objective: To characterize the underlying genetic defect in a family with 3 siblings affected by a severe, yet viable, congenital disorder. Methods: Extensive genetic and metabolic investigations were performed, and the affected children were imaged at different ages. Whole-genome genotyping and whole-exome sequencing were undertaken. A single large region (>8 Mb) of homozygosity in chromosome 4 (chr4:100,268,553–108,609,628) was identified that was shared only in affected siblings. Inspection of genetic variability within this region led to the identification of a novel mutation. Sanger sequencing confirmed segregation of the mutation with disease. Results: All affected siblings share homozygosity for a novel 4-bp deletion in the gene TBCK (NM_033115:c.614_617del:p.205_206del). Conclusions: This finding provides the genetic cause of a severe inherited disease in a family and extends the number of mutations and phenotypes associated with this recently identified disease gene. PMID:27275012

  7. 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

  8. 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

  9. 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

  10. Recessive mutations in RYR1 are a common cause of congenital fiber type disproportion.

    PubMed

    Clarke, Nigel F; Waddell, Leigh B; Cooper, Sandra T; Perry, Margaret; Smith, Robert L L; Kornberg, Andrew J; Muntoni, Francesco; Lillis, Suzanne; Straub, Volker; Bushby, Kate; Guglieri, Michela; King, Mary D; Farrell, Michael A; Marty, Isabelle; Lunardi, Joel; Monnier, Nicole; North, Kathryn N

    2010-07-01

    The main histological abnormality in congenital fiber type disproportion (CFTD) is hypotrophy of type 1 (slow twitch) fibers compared to type 2 (fast twitch) fibers. To investigate whether mutations in RYR1 are a cause of CFTD we sequenced RYR1 in seven CFTD families in whom the other known causes of CFTD had been excluded. We identified compound heterozygous changes in the RYR1 gene in four families (five patients), consistent with autosomal recessive inheritance. Three out of five patients had ophthalmoplegia, which may be the most specific clinical indication of mutations in RYR1. Type 1 fibers were at least 50% smaller, on average, than type 2 fibers in all biopsies. Recessive mutations in RYR1 are a relatively common cause of CFTD and can be associated with extreme fiber size disproportion. PMID:20583297

  11. 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

  12. Mutations in FKBP10 Cause Recessive Osteogenesis Imperfecta and Bruck Syndrome

    PubMed Central

    Kelley, Brian P; Malfait, Fransiska; Bonafe, Luisa; Baldridge, Dustin; Homan, Erica; Symoens, Sofie; Willaert, Andy; Elcioglu, Nursel; Van Maldergem, Lionel; Verellen-Dumoulin, Christine; Gillerot, Yves; Napierala, Dobrawa; Krakow, Deborah; Beighton, Peter; Superti-Furga, Andrea; De Paepe, Anne; Lee, Brendan

    2011-01-01

    Osteogenesis imperfecta (OI) is a genetic disorder of connective tissue characterized by bone fragility and alteration in synthesis and posttranslational modification of type I collagen. Autosomal dominant OI is caused by mutations in the genes (COL1A1 or COL1A2) encoding the chains of type I collagen. Bruck syndrome is a recessive disorder featuring congenital contractures in addition to bone fragility; Bruck syndrome type 2 is caused by mutations in PLOD2 encoding collagen lysyl hydroxylase, whereas Bruck syndrome type 1 has been mapped to chromosome 17, with evidence suggesting region 17p12, but the gene has remained elusive so far. Recently, the molecular spectrum of OI has been expanded with the description of the basis of a unique posttranslational modification of type I procollagen, that is, 3-prolyl-hydroxylation. Three proteins, cartilage-associated protein (CRTAP), prolyl-3-hydroxylase-1 (P3H1, encoded by the LEPRE1 gene), and the prolyl cis-trans isomerase cyclophilin-B (PPIB), form a complex that is required for fibrillar collagen 3-prolyl-hydroxylation, and mutations in each gene have been shown to cause recessive forms of OI. Since then, an additional putative collagen chaperone complex, composed of FKBP10 (also known as FKBP65) and SERPINH1 (also known as HSP47), also has been shown to be mutated in recessive OI. Here we describe five families with OI-like bone fragility in association with congenital contractures who all had FKBP10 mutations. Therefore, we conclude that FKBP10 mutations are a cause of recessive osteogenesis imperfecta and Bruck syndrome, possibly Bruck syndrome Type 1 since the location on chromosome 17 has not been definitely localized. © 2011 American Society for Bone and Mineral Research. PMID:20839288

  13. 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

  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. 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

  18. 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.

  19. 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

  20. PNPLA1 mutations cause autosomal recessive congenital ichthyosis in golden retriever dogs and humans.

    PubMed

    Grall, Anaïs; Guaguère, Eric; Planchais, Sandrine; Grond, Susanne; Bourrat, Emmanuelle; Hausser, Ingrid; Hitte, Christophe; Le Gallo, Matthieu; Derbois, Céline; Kim, Gwang-Jin; Lagoutte, Laëtitia; Degorce-Rubiales, Frédérique; Radner, Franz P W; Thomas, Anne; Küry, Sébastien; Bensignor, Emmanuel; Fontaine, Jacques; Pin, Didier; Zimmermann, Robert; Zechner, Rudolf; Lathrop, Mark; Galibert, Francis; André, Catherine; Fischer, Judith

    2012-02-01

    Ichthyoses comprise a heterogeneous group of genodermatoses characterized by abnormal desquamation over the whole body, for which the genetic causes of several human forms remain unknown. We used a spontaneous dog model in the golden retriever breed, which is affected by a lamellar ichthyosis resembling human autosomal recessive congenital ichthyoses (ARCI), to carry out a genome-wide association study. We identified a homozygous insertion-deletion (indel) mutation in PNPLA1 that leads to a premature stop codon in all affected golden retriever dogs. We subsequently found one missense and one nonsense mutation in the catalytic domain of human PNPLA1 in six individuals with ARCI from two families. Further experiments highlighted the importance of PNPLA1 in the formation of the epidermal lipid barrier. This study identifies a new gene involved in human ichthyoses and provides insights into the localization and function of this yet uncharacterized member of the PNPLA protein family. PMID:22246504

  1. An autosomal recessive mutation of DSG4 causes monilethrix through the ER stress response.

    PubMed

    Kato, Madoka; Shimizu, Akira; Yokoyama, Yoko; Kaira, Kyoichi; Shimomura, Yutaka; Ishida-Yamamoto, Akemi; Kamei, Kiyoko; Tokunaga, Fuminori; Ishikawa, Osamu

    2015-05-01

    Monilethrix is a hair shaft anomaly characterized by beaded hair with periodic changes in hair thickness. Mutations in the desmoglein 4 (DSG4) gene reportedly underlie the autosomal recessive form of the disease. However, the pathogenesis and cellular basis for the DSG4 mutation-induced monilethrix remained largely unknown. We report a Japanese female patient with monilethrix. Observation of her hair shaft by means of transmission electron microscopy showed fewer desmosomes and abnormal keratinization. Genetic analysis revealed a homozygous mutation, c.2119delG (p.Asp707Ilefs*109), in the DSG4 gene, which was predicted to cause a frameshift and premature termination in the intracellular region of the DSG4 protein. The mutation has not been reported previously. In the patient's hair shaft, we detected reduced but partial expression of the mutant DSG4 protein. Cellular analyses demonstrated that the mutant DSG4 lost its affinity to plakoglobin and accumulated in the endoplasmic reticulum (ER). The amounts of mutant DSG4 were increased by proteasome inhibitor treatment, and the expression of an ER chaperone, GRP78/BiP, was elevated in the patient's skin. Collectively, these results suggest that the dysfunctional mutated DSG4, tethered in the ER, undergoes ER-associated degradation, leading to unfolded protein response induction, and thus ER stress may have a role in the pathogenesis of monilethrix. PMID:25615553

  2. Mutations in CAPN1 Cause Autosomal-Recessive Hereditary Spastic Paraplegia.

    PubMed

    Gan-Or, Ziv; Bouslam, Naima; Birouk, Nazha; Lissouba, Alexandra; Chambers, Daniel B; Vérièpe, Julie; Androschuck, Alaura; Laurent, Sandra B; Rochefort, Daniel; Spiegelman, Dan; Dionne-Laporte, Alexandre; Szuto, Anna; Liao, Meijiang; Figlewicz, Denise A; Bouhouche, Ahmed; Benomar, Ali; Yahyaoui, Mohamed; Ouazzani, Reda; Yoon, Grace; Dupré, Nicolas; Suchowersky, Oksana; Bolduc, Francois V; Parker, J Alex; Dion, Patrick A; Drapeau, Pierre; Rouleau, Guy A; Bencheikh, Bouchra Ouled Amar

    2016-05-01

    Hereditary spastic paraplegia (HSP) is a genetically and clinically heterogeneous disease characterized by spasticity and weakness of the lower limbs with or without additional neurological symptoms. Although more than 70 genes and genetic loci have been implicated in HSP, many families remain genetically undiagnosed, suggesting that other genetic causes of HSP are still to be identified. HSP can be inherited in an autosomal-dominant, autosomal-recessive, or X-linked manner. In the current study, we performed whole-exome sequencing to analyze a total of nine affected individuals in three families with autosomal-recessive HSP. Rare homozygous and compound-heterozygous nonsense, missense, frameshift, and splice-site mutations in CAPN1 were identified in all affected individuals, and sequencing in additional family members confirmed the segregation of these mutations with the disease (spastic paraplegia 76 [SPG76]). CAPN1 encodes calpain 1, a protease that is widely present in the CNS. Calpain 1 is involved in synaptic plasticity, synaptic restructuring, and axon maturation and maintenance. Three models of calpain 1 deficiency were further studied. In Caenorhabditis elegans, loss of calpain 1 function resulted in neuronal and axonal dysfunction and degeneration. Similarly, loss-of-function of the Drosophila melanogaster ortholog calpain B caused locomotor defects and axonal anomalies. Knockdown of calpain 1a, a CAPN1 ortholog in Danio rerio, resulted in abnormal branchiomotor neuron migration and disorganized acetylated-tubulin axonal networks in the brain. The identification of mutations in CAPN1 in HSP expands our understanding of the disease causes and potential mechanisms. PMID:27153400

  3. 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

  4. ATOH7 mutations cause autosomal recessive persistent hyperplasia of the primary vitreous

    PubMed Central

    Prasov, Lev; Masud, Tehmina; Khaliq, Shagufta; Mehdi, S. Qasim; Abid, Aiysha; Oliver, Edward R.; Silva, Eduardo D.; Lewanda, Amy; Brodsky, Michael C.; Borchert, Mark; Kelberman, Daniel; Sowden, Jane C.; Dattani, Mehul T.; Glaser, Tom

    2012-01-01

    The vertebrate basic helix–loop–helix (bHLH) transcription factor ATOH7 (Math5) is specifically expressed in the embryonic neural retina and is required for the genesis of retinal ganglion cells (RGCs) and optic nerves. In Atoh7 mutant mice, the absence of trophic factors secreted by RGCs prevents the development of the intrinsic retinal vasculature and the regression of fetal blood vessels, causing persistent hyperplasia of the primary vitreous (PHPV). We therefore screened patients with hereditary PHPV, as well as bilateral optic nerve aplasia (ONA) or hypoplasia (ONH), for mutations in ATOH7. We identified a homozygous ATOH7 mutation (N46H) in a large family with an autosomal recessive PHPV disease trait linked to 10q21, and a heterozygous variant (R65G, p.Arg65Gly) in one of five sporadic ONA patients. High-density single-nucleotide polymorphism analysis also revealed a CNTN4 duplication and an OTX2 deletion in the ONA cohort. Functional analysis of ATOH7 bHLH domain substitutions, by electrophoretic mobility shift and luciferase cotransfection assays, revealed that the N46H variant cannot bind DNA or activate transcription, consistent with structural modeling. The N46H variant also failed to rescue RGC development in mouse Atoh7−/− retinal explants. The R65G variant retains all of these activities, similar to wild-type human ATOH7. Our results strongly suggest that autosomal recessive persistent hyperplastic primary vitreous is caused by N46H and is etiologically related to nonsyndromic congenital retinal nonattachment. The R65G allele, however, cannot explain the ONA phenotype. Our study firmly establishes ATOH7 as a retinal disease gene and provides a functional basis to analyze new coding variants. PMID:22645276

  5. 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

  6. 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

  7. Functional analysis of FOXE3 mutations causing dominant and recessive ocular anterior segment disease.

    PubMed

    Islam, Lily; Kelberman, Daniel; Williamson, Laura; Lewis, Nicola; Glindzicz, Maria Bitner; Nischal, Ken K; Sowden, Jane C

    2015-03-01

    Mutations in FOXE3 are associated with both recessive and dominant inheritance of severe anterior ocular malformations and glaucoma. However, functional analyses of putative pathogenic mutations have not been performed. We tested the hypothesis that variations in FOXE3 activity underlie the different modes of inheritance and disease phenotype. In band shift assays, three recessive mutants showed loss-of-function, one retained DNA binding activity, whereas two dominant mutants showed altered activity. All six mutants showed reduced transactivation function compared with wild-type, and modeling the heterozygous state resulted in an intermediate level of activity providing no evidence for dominant negative action. Our in vitro data are consistent with loss-of-function below a dosage sensitive threshold as a mechanism of action for recessive mutations, but indicate an altered mutant protein function rather than a haploinsufficient mechanism for dominant mutations. This study provides the first functional evidence demonstrating that FOXE3 mutations identified in patients impair protein function with differential effects. PMID:25504734

  8. 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

  9. Recessive mutations in the α3 (VI) collagen gene COL6A3 cause early-onset isolated dystonia.

    PubMed

    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

    2015-06-01

    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

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

    PubMed

    Duan, Ranhui; Shi, Yuting; 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

  11. 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

  12. A hypofunctional PAX1 mutation causes autosomal recessively inherited otofaciocervical syndrome.

    PubMed

    Pohl, Esther; Aykut, Ayca; Beleggia, Filippo; Karaca, Emin; Durmaz, Burak; Keupp, Katharina; Arslan, Esra; Palamar, Melis; Onay, Melis Palamar; Yigit, Gökhan; Özkinay, Ferda; Wollnik, Bernd

    2013-11-01

    Otofaciocervical syndrome (OFCS) is an autosomal recessively inherited disorder characterized by facial dysmorphism, external ear anomalies with preauricular pits and hearing impairment, branchial cysts or fistulas, anomalies of the vertebrae and the shoulder girdle, and mild intellectual disability. In a large consanguineous family with OFCS from Turkey, we performed whole-exome sequencing (WES) of a single pooled DNA sample of four affected individuals. Filtering for variants with a percentage of alternate reads ≥ 90 % and a coverage of at least five reads identified only a single novel homozygous variant, c.497G>T, located in PAX1 that co-segregated with the disease in the family. PAX1 encodes a transcription factor with a critical role in pattern formation during embryogenesis in vertebrates. The mutation is predicted to substitute the glycine at position 166 to valine (p.G166V) within the highly conserved paired-box domain of the PAX1 protein. We performed a dual luciferase reporter assay to examine the transactivation of a regulatory sequence in the Nkx3-2 promoter region, which is a direct target of mouse Pax1 transcriptional regulation. We observed a significantly reduced transactivation in HEK293T cells overexpressing Pax1(G157V) in comparison to Pax1(WT) expressing cells, indicating a reduced DNA-binding affinity of the mutant protein. Taken together, our results show that the strategy of pooling DNA is a powerful, cost-effective application for WES in consanguineous families and establish PAX1 as a new disease-causing gene for OFCS and as part of the EYA-DACH-SIX-PAX network, important in early embryogenesis. PMID:23851939

  13. 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

  14. 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

  15. Mutations in CERS3 cause autosomal recessive congenital ichthyosis in humans.

    PubMed

    Radner, Franz P W; Marrakchi, Slaheddine; Kirchmeier, Peter; Kim, Gwang-Jin; Ribierre, Florence; Kamoun, Bourane; Abid, Leila; Leipoldt, Michael; Turki, Hamida; Schempp, Werner; Heilig, Roland; Lathrop, Mark; Fischer, Judith

    2013-06-01

    Autosomal recessive congenital ichthyosis (ARCI) is a rare genetic disorder of the skin characterized by abnormal desquamation over the whole body. In this study we report four patients from three consanguineous Tunisian families with skin, eye, heart, and skeletal anomalies, who harbor a homozygous contiguous gene deletion syndrome on chromosome 15q26.3. Genome-wide SNP-genotyping revealed a homozygous region in all affected individuals, including the same microdeletion that partially affects two coding genes (ADAMTS17, CERS3) and abolishes a sequence for a long non-coding RNA (FLJ42289). Whereas mutations in ADAMTS17 have recently been identified in autosomal recessive Weill-Marchesani-like syndrome in humans and dogs presenting with ophthalmologic, cardiac, and skeletal abnormalities, no disease associations have been described for CERS3 (ceramide synthase 3) and FLJ42289 so far. However, analysis of additional patients with non-syndromic ARCI revealed a splice site mutation in CERS3 indicating that a defect in ceramide synthesis is causative for the present skin phenotype of our patients. Functional analysis of patient skin and in vitro differentiated keratinocytes demonstrated that mutations in CERS3 lead to a disturbed sphingolipid profile with reduced levels of epidermis-specific very long-chain ceramides that interferes with epidermal differentiation. Taken together, these data present a novel pathway involved in ARCI development and, moreover, provide the first evidence that CERS3 plays an essential role in human sphingolipid metabolism for the maintenance of epidermal lipid homeostasis. PMID:23754960

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

    PubMed

    de la Dure-Molla, Muriel; Quentric, Mickael; Yamaguti, Paulo Marcio; Acevedo, Ana-Carolina; Mighell, Alan J; Vikkula, Miikka; Huckert, Mathilde; Berdal, Ariane; Bloch-Zupan, Agnes

    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

  17. 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

  18. Nonsense mutation in MERTK causes autosomal recessive retinitis pigmentosa in a consanguineous Pakistani family

    PubMed Central

    Shahzadi, Amber; Riazuddin, S Amer; Ali, Shahbaz; Li, David; Khan, Shaheen N; Husnain, Tayyab; Akram, Javed; Sieving, Paul A; Hejtmancik, J Fielding; Riazuddin, Sheikh

    2012-01-01

    Background Retinitis pigmentosa (RP) is one of the most common ophthalmic disorders affecting one in approximately 5000 people worldwide. A nuclear family was recruited from the Punjab province of Pakistan to study the genetic basis of autosomal recessive RP. Methods All affected individuals underwent a thorough ophthalmic examination and the disease was characterised based upon results for fundus photographs and electroretinogram recordings. Genomic DNA was extracted from peripheral leucocytes. Exclusion studies were performed with short tandem repeat (STR) markers flanking reported autosomal recessive RP loci. Haplotypes were constructed and results were statistically evaluated. Results The results of exclusion analyses suggested that family PKRP173 was linked to chromosome 2q harbouring mer tyrosine kinase protooncogene (MERTK), a gene previously associated with autosomal recessive RP. Additional STR markers refined the critical interval and placed it in a 13.4 cM (17 Mb) region flanked by D2S293 proximally and D2S347 distally. Significant logarithm of odds (LOD) scores of 3.2, 3.25 and 3.18 at θ=0 were obtained with markers D2S1896, D2S2269 and D2S160. Sequencing of the coding exons of MERTK identified a mutation, c.718G→T in exon 4, which results in a premature termination of p.E240X that segregates with the disease phenotype in the family. Conclusion Our results strongly suggest that the nonsense mutation in MERTK, leading to premature termination of the protein, is responsible for RP phenotype in the affected individuals of the Pakistani family. PMID:20538656

  19. Mutations in zinc finger 407 [ZNF407] cause a unique autosomal recessive cognitive impairment syndrome

    PubMed Central

    2014-01-01

    Background A consanguineous Arab family is affected by an apparently novel autosomal recessive disorder characterized by cognitive impairment, failure-to-thrive, hypotonia and dysmorphic features including bilateral ptosis and epicanthic folds, synophrys, midface hypoplasia, downturned mouth corners, thin upper vermillion border and prominent ears, bilateral 5th finger camptodactyly, bilateral short 4th metatarsal bones, and limited knee mobility bilaterally. Methods The family was studied by homozygosity mapping, candidate gene mutation screening and whole Exome Next Generation Sequencing of a single affected member to identify the offending gene and mutation. The mutated gene product was studied by structural bioinformatics methods. Results A damaging c.C5054G mutation affecting an evolutionary highly conserved amino acid p.S1685W was identified in the ZNF407 gene at 18q23. The Serine to Tryptophane mutation affects two of the three ZNF407 isoforms and is located in the last third of the protein, in a linker peptide adjoining two zinc-finger domains. Structural analyses of this mutation shows disruption of an H-bond that locks the relative spatial position of the two fingers, leading to a higher flexibility of the linker and thus to a decreased probability of binding to the target DNA sequence essentially eliminating the functionality of downstream domains and interfering with the expression of various genes under ZNF407 control during fetal brain development. Conclusions ZNF407 is a transcription factor with an essential role in brain development. When specific and limited in number homozygosity intervals exist that harbor the offending gene in consanguineous families, Whole Exome Sequencing of a single affected individual is an efficient approach to gene mapping and mutation identification. PMID:24907849

  20. A newly described mutation of the CLCN7 gene causes neuropathic autosomal recessive osteopetrosis in an Arab family.

    PubMed

    Al-Aama, Jumana Y; Dabbagh, Amal A; Edrees, Alaa Y

    2012-01-01

    Neurologic manifestations in osteopetrosis are usually secondary to sclerosis of the skull bones. However, a rare neuropathic subtype of osteopetrosis exists that resembles neurodegenerative storage disorders. Unlike other forms of osteopetrosis, this latter form does not respond to hematopoietic stem cell transplantation. Preliminary studies suggest that this neuropathic form is more likely to be caused by mutations in the CLCN7 gene in an autosomal recessive manner. This study provides further evidence for this phenotype-genotype correlation by presenting a previously unreported mutation in the CLCN7 gene in a Yemeni family with the neuropathic form. This is also the first study of any mutation in patients with osteopetrosis of Arabic ethnicity. As literature review suggests that this type may be more common in Arabs, cascade genetic screening of early onset of autosomal recessive-osteopetrosis in patients of Arabic ancestry may preferably start with the CLCN7 gene rather than the TCIRG gene as is routinely done in clinical laboratories. Identifying a mutation in the CLCN7 gene in a patient with early onset of autosomal recessive-osteopetrosis may also guide therapeutic decisions including the option of hematopoietic stem cell transplantation. PMID:21946807

  1. 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

  2. Mutations in SNX14 cause a distinctive autosomal-recessive cerebellar ataxia and intellectual disability syndrome.

    PubMed

    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

    2014-11-01

    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

  3. 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

  4. A case report: Autosomal recessive microcephaly caused by a novel mutation in MCPH1 gene.

    PubMed

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

    2015-10-15

    Autosomal Recessive Primary Microcephaly (MCPH-MIM 251200) is distinguished by congenital decrease in occipito-frontal head circumference (OFC) of at least 2 standard deviations (SD) below population average in addition to non-progressive mental retardation, without any prominent neurological disorder. Mutations in MCPH1, which encodes the protein microcephalin have been detected in this disorder. Here we report a consanguineous Iranian family with 2 children affected with microcephaly. Despite the severe mental retardation observed in the male patient, the female patient had normal intelligent with no delay in motor milestones or speech. A novel splice-acceptor site homozygous mutation has been detected in intron 4 of MCPH1 gene (c.322-2A>T) which results in an RNA processing defect with a 15-nucleotide deletion in exon 5 of the mRNA transcript (r.322_336del15, p.R108_Q112del5). This novel mutation has resulted in different phenotypes in affected male and female patients of this family. The sex-specific variations in gene regulation during brain development may partially explain such difference in phenotypes probably in addition to other mechanisms such as modifier genes. PMID:26192461

  5. 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

  6. Mutations in the Beta Propeller WDR72 Cause Autosomal-Recessive Hypomaturation Amelogenesis Imperfecta

    PubMed Central

    El-Sayed, Walid; Parry, David A.; Shore, Roger C.; Ahmed, Mushtaq; Jafri, Hussain; Rashid, Yasmin; Al-Bahlani, Suhaila; Al Harasi, Sharifa; Kirkham, Jennifer; Inglehearn, Chris F.; Mighell, Alan J.

    2009-01-01

    Healthy dental enamel is the hardest and most highly mineralized human tissue. Though acellular, nonvital, and without capacity for turnover or repair, it can nevertheless last a lifetime. Amelogenesis imperfecta (AI) is a collective term for failure of normal enamel development, covering diverse clinical phenotypes that typically show Mendelian inheritance patterns. One subset, known as hypomaturation AI, is characterised by near-normal volumes of organic enamel matrix but with weak, creamy-brown opaque enamel that fails prematurely after tooth eruption. Mutations in genes critical to enamel matrix formation have been documented, but current understanding of other key events in enamel biomineralization is limited. We investigated autosomal-recessive hypomaturation AI in a consanguineous Pakistani family. A whole-genome SNP autozygosity screen identified a locus on chromosome 15q21.3. Sequencing candidate genes revealed a point mutation in the poorly characterized WDR72 gene. Screening of WDR72 in a panel of nine additional hypomaturation AI families revealed the same mutation in a second, apparently unrelated, Pakistani family and two further nonsense mutations in Omani families. Immunohistochemistry confirmed intracellular localization in maturation-stage ameloblasts. WDR72 function is unknown, but as a putative β propeller is expected to be a scaffold for protein-protein interactions. The nearest homolog, WDR7, is involved in vesicle mobilization and Ca2+-dependent exocytosis at synapses. Vesicle trafficking is important in maturation-stage ameloblasts with respect to secretion into immature enamel and removal of cleaved enamel matrix proteins via endocytosis. This raises the intriguing possibility that WDR72 is critical to ameloblast vesicle turnover during enamel maturation. PMID:19853237

  7. A recessive homozygous p.Asp92Gly SDHD mutation causes prenatal cardiomyopathy and a severe mitochondrial complex II deficiency.

    PubMed

    Alston, Charlotte L; Ceccatelli Berti, Camilla; Blakely, Emma L; Oláhová, Monika; He, Langping; McMahon, Colin J; Olpin, Simon E; Hargreaves, Iain P; Nolli, Cecilia; McFarland, Robert; Goffrini, Paola; O'Sullivan, Maureen J; Taylor, Robert W

    2015-08-01

    Succinate dehydrogenase (SDH) is a crucial metabolic enzyme complex that is involved in ATP production, playing roles in both the tricarboxylic cycle and the mitochondrial respiratory chain (complex II). Isolated complex II deficiency is one of the rarest oxidative phosphorylation disorders with mutations described in three structural subunits and one of the assembly factors; just one case is attributed to recessively inherited SDHD mutations. We report the pathological, biochemical, histochemical and molecular genetic investigations of a male neonate who had left ventricular hypertrophy detected on antenatal scan and died on day one of life. Subsequent postmortem examination confirmed hypertrophic cardiomyopathy with left ventricular non-compaction. Biochemical analysis of his skeletal muscle biopsy revealed evidence of a severe isolated complex II deficiency and candidate gene sequencing revealed a novel homozygous c.275A>G, p.(Asp92Gly) SDHD mutation which was shown to be recessively inherited through segregation studies. The affected amino acid has been reported as a Dutch founder mutation p.(Asp92Tyr) in families with hereditary head and neck paraganglioma. By introducing both mutations into Saccharomyces cerevisiae, we were able to confirm that the p.(Asp92Gly) mutation causes a more severe oxidative growth phenotype than the p.(Asp92Tyr) mutant, and provides functional evidence to support the pathogenicity of the patient's SDHD mutation. This is only the second case of mitochondrial complex II deficiency due to inherited SDHD mutations and highlights the importance of sequencing all SDH genes in patients with biochemical and histochemical evidence of isolated mitochondrial complex II deficiency. PMID:26008905

  8. An unbalanced translocation unmasks a recessive mutation in the follicle-stimulating hormone receptor (FSHR) gene and causes FSH resistance

    PubMed Central

    Kuechler, Amla; Hauffa, Berthold P; Köninger, Angela; Kleinau, Gunnar; Albrecht, Beate; Horsthemke, Bernhard; Gromoll, Jörg

    2010-01-01

    Follicle-stimulating hormone (FSH) mediated by its receptor (FSHR) is pivotal for normal gametogenesis. Inactivating FSHR mutations are known to cause hypergonadotropic hypogonadism with disturbed follicular maturation in females. So far, only very few recessive point mutations have been described. We report on a 17-year-old female with primary amenorrhea, hypergonadotropic hypogonadism and disturbed folliculogenesis. Chromosome analysis detected a seemingly balanced translocation 46,XX,t(2;8)(p16.3or21;p23.1)mat. FSHR sequence analysis revealed a novel non-synonymous point mutation in exon 10 (c.1760C>A, p.Pro587His), but no wild-type allele. The mutation was also found in the father, but not in the mother. Furthermore, molecular-cytogenetic analyses of the breakpoint region on chromosome 2 showed the translocation to be unbalanced, containing a deletion with one breakpoint within the FSHR gene. The deletion size was narrowed down by array analysis to approximately 163 kb, involving exons 9 and 10 of the FSHR gene. Functional studies of the mutation revealed the complete lack of signal transduction presumably caused by a changed conformational structure of transmembrane helix 6. To our knowledge, this is the first description of a compound heterozygosity of an inactivating FSHR point mutation unmasked by a partial deletion. This coincidence of two rare changes caused clinical signs consistent with FSH resistance. PMID:20087398

  9. Recessive germline SDHA and SDHB mutations causing leukodystrophy and isolated mitochondrial complex II deficiency

    PubMed Central

    Alston, Charlotte L; Davison, James E; Meloni, Francesca; van der Westhuizen, Francois H; He, Langping; Hornig-Do, Hue-Tran; Peet, Andrew C; Gissen, Paul; Goffrini, Paola; Ferrero, Ileana; Wassmer, Evangeline; McFarland, Robert; Taylor, Robert W

    2012-01-01

    Background Isolated complex II deficiency is a rare form of mitochondrial disease, accounting for approximately 2% of all respiratory chain deficiency diagnoses. The succinate dehydrogenase (SDH) genes (SDHA, SDHB, SDHC and SDHD) are autosomally-encoded and transcribe the conjugated heterotetramers of complex II via the action of two known assembly factors (SDHAF1 and SDHAF2). Only a handful of reports describe inherited SDH gene defects as a cause of paediatric mitochondrial disease, involving either SDHA (Leigh syndrome, cardiomyopathy) or SDHAF1 (infantile leukoencephalopathy). However, all four SDH genes, together with SDHAF2, have known tumour suppressor functions, with numerous germline and somatic mutations reported in association with hereditary cancer syndromes, including paraganglioma and pheochromocytoma. Methods and results Here, we report the clinical and molecular investigations of two patients with histochemical and biochemical evidence of a severe, isolated complex II deficiency due to novel SDH gene mutations; the first patient presented with cardiomyopathy and leukodystrophy due to compound heterozygous p.Thr508Ile and p.Ser509Leu SDHA mutations, while the second patient presented with hypotonia and leukodystrophy with elevated brain succinate demonstrated by MR spectroscopy due to a novel, homozygous p.Asp48Val SDHB mutation. Western blotting and BN-PAGE studies confirmed decreased steady-state levels of the relevant SDH subunits and impairment of complex II assembly. Evidence from yeast complementation studies provided additional support for pathogenicity of the SDHB mutation. Conclusions Our report represents the first example of SDHB mutation as a cause of inherited mitochondrial respiratory chain disease and extends the SDHA mutation spectrum in patients with isolated complex II deficiency. PMID:22972948

  10. A novel mutation in the EDAR gene causes severe autosomal recessive hypohidrotic ectodermal dysplasia.

    PubMed

    Henningsen, Emil; Svendsen, Mathias Tiedemann; Lildballe, Dorte Launholt; Jensen, Peter Kjestrup Axel

    2014-08-01

    We report on a 2-year-old girl presenting with a severe form of hypohidrotic ectodermal dysplasia (HED). The patient presented with hypotrichosis, anodontia, hypohidrosis, frontal bossing, prominent lips and ears, dry, pale skin, and dermatitis. The patient had chronic rhinitis with malodorous nasal discharge. The girl was the second born child of first-cousin immigrants from Northern Iraq. A novel homozygous mutation (c.84delC) in the EDAR gene was identified. This mutation most likely causes a frameshift in the protein product (p.S29fs*74). This results in abolition of all ectodysplasin-mediated NF-kB signalling. This complete loss-of-function mutation likely accounts for the severe clinical abnormalities in ectodermal structures in the described patient. PMID:24764207

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

    PubMed Central

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

    2014-01-01

    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. PMID:24619944

  12. Mutations in the lipase-H gene causing autosomal recessive hypotrichosis and woolly hair.

    PubMed

    Mehmood, Sabba; Jan, Abid; Muhammad, Dost; Ahmad, Farooq; Mir, Hina; Younus, Muhammad; Ali, Ghazanfar; Ayub, Muhammad; Ansar, Muhammad; Ahmad, Wasim

    2015-08-01

    Hypotrichosis is characterised by sparse scalp hair, sparse to absent eyebrows and eyelashes, or absence of hair from other parts of the body. In few cases, the condition is associated with tightly curled woolly scalp hair. The present study searched for disease-causing sequence variants in the genes in four Pakistani lineal consanguineous families exhibiting features of hypotrichosis or woolly hair. A haplotype analysis established links in all four families to the LIPH gene located on chromosome 3q27.2. Subsequently, sequencing LIPH identified a novel non-sense mutation (c.328C>T; p.Arg110*) in one and a previously reported 2-bp deletion mutation (c.659_660delTA, p.Ile220ArgfsX29) in three other families. PMID:24628704

  13. Autosomal Recessive Hypotrichosis with Woolly Hair Caused by a Mutation in the Keratin 25 Gene Expressed in Hair Follicles.

    PubMed

    Zernov, Nikolay V; Skoblov, Mikhail Y; Marakhonov, Andrey V; Shimomura, Yutaka; Vasilyeva, Tatyana A; Konovalov, Fedor A; Abrukova, Anna V; Zinchenko, Rena A

    2016-06-01

    Hypotrichosis is an abnormal condition characterized by decreased hair density and various defects in hair structure and growth patterns. In particular, in woolly hair, hypotrichosis is characterized by a tightly curled structure and abnormal growth. In this study, we present a detailed comparative examination of individuals affected by autosomal-recessive hypotrichosis (ARH), which distinguishes two types of ARH. Earlier, we demonstrated that exon 4 deletion in the lipase H gene caused an ARH (hypotrichosis 7; MIM: 604379) in populations of the Volga-Ural region of Russia. Screening for this mutation in all affected individuals revealed its presence only in the group with the hypotrichosis 7 phenotype. Other patients formed a separate group of woolly hair-associated ARH, with a homozygous missense mutation c.712G>T (p.Val238Leu) in a highly conserved position of type I keratin KRT25 (K25). Haplotype analysis indicated a founder effect. An expression study in the HaCaT cell line demonstrated a deleterious effect of the p.Val238Leu mutation on the formation of keratin intermediate filaments. Hence, we have identified a previously unreported missense mutation in the KRT25 gene causing ARH with woolly hair. PMID:26902920

  14. 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

  15. Homozygosity mapping reveals mutations of GRXCR1 as a cause of autosomal-recessive nonsyndromic hearing impairment.

    PubMed

    Schraders, Margit; Lee, Kwanghyuk; Oostrik, Jaap; Huygen, Patrick L M; Ali, Ghazanfar; Hoefsloot, Lies H; Veltman, Joris A; Cremers, Frans P M; Basit, Sulman; Ansar, Muhammad; Cremers, Cor W R J; Kunst, Henricus P M; Ahmad, Wasim; Admiraal, Ronald J C; Leal, Suzanne M; Kremer, Hannie

    2010-02-12

    We identified overlapping homozygous regions within the DFNB25 locus in two Dutch and ten Pakistani families with sensorineural autosomal-recessive nonsyndromic hearing impairment (arNSHI). Only one of the families, W98-053, was not consanguineous, and its sibship pointed toward a reduced critical region of 0.9 Mb. This region contained the GRXCR1 gene, and the orthologous mouse gene was described to be mutated in the pirouette (pi) mutant with resulting hearing loss and circling behavior. Sequence analysis of the GRXCR1 gene in hearing-impaired family members revealed splice-site mutations in two Dutch families and a missense and nonsense mutation, respectively, in two Pakistani families. The splice-site mutations are predicted to cause frameshifts and premature stop codons. In family W98-053, this could be confirmed by cDNA analysis. GRXCR1 is predicted to contain a GRX-like domain. GRX domains are involved in reversible S-glutathionylation of proteins and thereby in the modulation of activity and/or localization of these proteins. The missense mutation is located in this domain, whereas the nonsense and splice-site mutations may result in complete or partial absence of the GRX-like domain or of the complete protein. Hearing loss in patients with GRXCR1 mutations is congenital and is moderate to profound. Progression of the hearing loss was observed in family W98-053. Vestibular dysfunction was observed in some but not all affected individuals. Quantitative analysis of GRXCR1 transcripts in fetal and adult human tissues revealed a preferential expression of the gene in fetal cochlea, which may explain the nonsyndromic nature of the hearing impairment. PMID:20137778

  16. 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

  17. A mutation of COX6A1 causes a recessive axonal or mixed form of Charcot-Marie-Tooth disease.

    PubMed

    Tamiya, Gen; Makino, Satoshi; Hayashi, Makiko; Abe, Akiko; Numakura, Chikahiko; Ueki, Masao; Tanaka, Atsushi; Ito, Chizuru; Toshimori, Kiyotaka; Ogawa, Nobuhiro; Terashima, Tomoya; Maegawa, Hiroshi; Yanagisawa, Daijiro; Tooyama, Ikuo; Tada, Masayoshi; Onodera, Osamu; Hayasaka, Kiyoshi

    2014-09-01

    Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy characterized by clinical and genetic heterogeneity. Although more than 30 loci harboring CMT-causing mutations have been identified, many other genes still remain to be discovered for many affected individuals. For two consanguineous families with CMT (axonal and mixed phenotypes), a parametric linkage analysis using genome-wide SNP chip identified a 4.3 Mb region on 12q24 showing a maximum multipoint LOD score of 4.23. Subsequent whole-genome sequencing study in one of the probands, followed by mutation screening in the two families, revealed a disease-specific 5 bp deletion (c.247-10_247-6delCACTC) in a splicing element (pyrimidine tract) of intron 2 adjacent to the third exon of cytochrome c oxidase subunit VIa polypeptide 1 (COX6A1), which is a component of mitochondrial respiratory complex IV (cytochrome c oxidase [COX]), within the autozygous linkage region. Functional analysis showed that expression of COX6A1 in peripheral white blood cells from the affected individuals and COX activity in their EB-virus-transformed lymphoblastoid cell lines were significantly reduced. In addition, Cox6a1-null mice showed significantly reduced COX activity and neurogenic muscular atrophy leading to a difficulty in walking. Those data indicated that COX6A1 mutation causes the autosomal-recessive axonal or mixed CMT. PMID:25152455

  18. A Mutation of COX6A1 Causes a Recessive Axonal or Mixed Form of Charcot-Marie-Tooth Disease

    PubMed Central

    Tamiya, Gen; Makino, Satoshi; Hayashi, Makiko; Abe, Akiko; Numakura, Chikahiko; Ueki, Masao; Tanaka, Atsushi; Ito, Chizuru; Toshimori, Kiyotaka; Ogawa, Nobuhiro; Terashima, Tomoya; Maegawa, Hiroshi; Yanagisawa, Daijiro; Tooyama, Ikuo; Tada, Masayoshi; Onodera, Osamu; Hayasaka, Kiyoshi

    2014-01-01

    Charcot-Marie-Tooth disease (CMT) is the most common inherited neuropathy characterized by clinical and genetic heterogeneity. Although more than 30 loci harboring CMT-causing mutations have been identified, many other genes still remain to be discovered for many affected individuals. For two consanguineous families with CMT (axonal and mixed phenotypes), a parametric linkage analysis using genome-wide SNP chip identified a 4.3 Mb region on 12q24 showing a maximum multipoint LOD score of 4.23. Subsequent whole-genome sequencing study in one of the probands, followed by mutation screening in the two families, revealed a disease-specific 5 bp deletion (c.247−10_247−6delCACTC) in a splicing element (pyrimidine tract) of intron 2 adjacent to the third exon of cytochrome c oxidase subunit VIa polypeptide 1 (COX6A1), which is a component of mitochondrial respiratory complex IV (cytochrome c oxidase [COX]), within the autozygous linkage region. Functional analysis showed that expression of COX6A1 in peripheral white blood cells from the affected individuals and COX activity in their EB-virus-transformed lymphoblastoid cell lines were significantly reduced. In addition, Cox6a1-null mice showed significantly reduced COX activity and neurogenic muscular atrophy leading to a difficulty in walking. Those data indicated that COX6A1 mutation causes the autosomal-recessive axonal or mixed CMT. PMID:25152455

  19. 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

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

    PubMed

    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

    2014-05-15

    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

  1. A novel compound heterozygous mutation in the BEST1 gene causes autosomal recessive Best vitelliform macular dystrophy

    PubMed Central

    Zhao, L; Grob, S; Corey, R; Krupa, M; Luo, J; Du, H; Lee, C; Hughes, G; Lee, J; Quach, J; Zhu, J; Shaw, P X; Kozak, I; Zhang, K

    2012-01-01

    Purpose To determine the genetic basis of early onset autosomal recessive Best vitelliform macular dystrophy (arBVMD) in a family with three affected children. Design Clinical and family-based genetic study. Methods Seven subjects making up a family with three children affected by Best vitelliform macular dystrophy were studied. Standard ophthalmic exam with dilated ophthalmoscopy and imaging were performed in each individual. The eleven exons of BEST1were directly sequenced. Results All three affected children have the clinical characteristic features of Best vitelliform macular dystrophy: large macular vitelliform lesions, scattered vitelliform lesions along the arcades and in the peripheral retina, and an accumulation of serous retinal fluid. A novel compound heterozygous mutation in the BEST1gene was found in the three affected individuals (L41P and I201T). The unaffected parents and children only harbor one heterozygous mutation. Conclusion arBVMD can be caused by the compound heterozygous mutation L41P and I201T in the BEST1gene. PMID:22422030

  2. Mutations in NALCN Cause an Autosomal-Recessive Syndrome with Severe Hypotonia, Speech Impairment, and Cognitive Delay

    PubMed Central

    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

    2013-01-01

    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

  3. Mutations in the chloride-bicarbonate exchanger gene AE1 cause autosomal dominant but not autosomal recessive distal renal tubular acidosis

    PubMed Central

    Karet, F. E.; Gainza, F. J.; Györy, A. Z.; Unwin, R. J.; Wrong, O.; Tanner, M. J. A.; Nayir, A.; Alpay, H.; Santos, F.; Hulton, S. A.; Bakkaloglu, A.; Ozen, S.; Cunningham, M. J.; di Pietro, A.; Walker, W. G.; Lifton, R. P.

    1998-01-01

    Primary distal renal tubular acidosis (dRTA) is characterized by reduced ability to acidify urine, variable hyperchloremic hypokalemic metabolic acidosis, nephrocalcinosis, and nephrolithiasis. Kindreds showing either autosomal dominant or recessive transmission are described. Mutations in the chloride-bicarbonate exchanger AE1 have recently been reported in four autosomal dominant dRTA kindreds, three of these altering codon Arg589. We have screened 26 kindreds with primary dRTA for mutations in AE1. Inheritance was autosomal recessive in seventeen kindreds, autosomal dominant in one, and uncertain due to unknown parental phenotype or sporadic disease in eight kindreds. No mutations in AE1 were detected in any of the autosomal recessive kindreds, and analysis of linkage showed no evidence of linkage of recessive dRTA to AE1. In contrast, heterozygous mutations in AE1 were identified in the one known dominant dRTA kindred, in one sporadic case, and one kindred with two affected brothers. In the dominant kindred, the mutation Arg-589/Ser cosegregated with dRTA in the extended pedigree. An Arg-589/His mutation in the sporadic case proved to be a de novo mutation. In the third kindred, affected brothers both have an intragenic 13-bp duplication resulting in deletion of the last 11 amino acids of AE1. These mutations were not detected in 80 alleles from unrelated normal individuals. These findings underscore the key role of Arg-589 and the C terminus in normal AE1 function, and indicate that while mutations in AE1 cause autosomal dominant dRTA, defects in this gene are not responsible for recessive disease. PMID:9600966

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

    PubMed

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

    2016-05-01

    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

  5. 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

  6. Hereditary spastic paraplegia with recessive trait caused by mutation in KLC4 gene.

    PubMed

    Bayrakli, Fatih; Poyrazoglu, Hatice Gamze; Yuksel, Sirin; Yakicier, Cengiz; Erguner, Bekir; Sagiroglu, Mahmut Samil; Yuceturk, Betul; Ozer, Bugra; Doganay, Selim; Tanrikulu, Bahattin; Seker, Askin; Akbulut, Fatih; Ozen, Ali; Per, Huseyin; Kumandas, Sefer; Altuner Torun, Yasemin; Bayri, Yasar; Sakar, Mustafa; Dagcinar, Adnan; Ziyal, Ibrahim

    2015-12-01

    We report an association between a new causative gene and spastic paraplegia, which is a genetically heterogeneous disorder. Clinical phenotyping of one consanguineous family followed by combined homozygosity mapping and whole-exome sequencing analysis. Three patients from the same family shared common features of progressive complicated spastic paraplegia. They shared a single homozygous stretch area on chromosome 6. Whole-exome sequencing revealed a homozygous mutation (c.853_871del19) in the gene coding the kinesin light chain 4 protein (KLC4). Meanwhile, the unaffected parents and two siblings were heterozygous and one sibling was homozygous wild type. The 19 bp deletion in exon 6 generates a stop codon and thus a truncated messenger RNA and protein. The association of a KLC4 mutation with spastic paraplegia identifies a new locus for the disease. PMID:26423925

  7. 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

  8. Mutations in TPRN cause a progressive form of autosomal-recessive nonsyndromic hearing loss.

    PubMed

    Li, Yun; Pohl, Esther; Boulouiz, Redouane; Schraders, Margit; Nürnberg, Gudrun; Charif, Majida; Admiraal, Ronald J C; von Ameln, Simon; Baessmann, Ingelore; Kandil, Mostafa; Veltman, Joris A; Nürnberg, Peter; Kubisch, Christian; Barakat, Abdelhamid; Kremer, Hannie; Wollnik, Bernd

    2010-03-12

    We performed genome-wide homozygosity mapping in a large consanguineous family from Morocco and mapped the autosomal-recessive nonsyndromic hearing loss (ARNSHL) in this family to the DFNB79 locus on chromosome 9q34. By sequencing of 62 positional candidate genes of the critical region, we identified a causative homozygous 11 bp deletion, c.42_52del, in the TPRN gene in all seven affected individuals. The deletion is located in exon 1 and results in a frameshift and premature protein truncation (p.Gly15AlafsX150). Interestingly, the deleted sequence is part of a repetitive and CG-rich motive predicted to be prone to structural aberrations during crossover formation. We identified another family with progressive ARNSHL linked to this locus, whose affected members were shown to carry a causative 1 bp deletion (c.1347delG) in exon 1 of TPRN. The function of the encoded protein, taperin, is unknown; yet, partial homology to the actin-caping protein phostensin suggests a role in actin dynamics. PMID:20170898

  9. Autosomal-Recessive Mutations in SLC34A1 Encoding Sodium-Phosphate Cotransporter 2A Cause Idiopathic Infantile Hypercalcemia.

    PubMed

    Schlingmann, Karl P; Ruminska, Justyna; Kaufmann, Martin; Dursun, Ismail; Patti, Monica; Kranz, Birgitta; Pronicka, Ewa; Ciara, Elzbieta; Akcay, Teoman; Bulus, Derya; Cornelissen, Elisabeth A M; Gawlik, Aneta; Sikora, Przemysław; Patzer, Ludwig; Galiano, Matthias; Boyadzhiev, Veselin; Dumic, Miroslav; Vivante, Asaf; Kleta, Robert; Dekel, Benjamin; Levtchenko, Elena; Bindels, René J; Rust, Stephan; Forster, Ian C; Hernando, Nati; Jones, Glenville; Wagner, Carsten A; Konrad, Martin

    2016-02-01

    Idiopathic infantile hypercalcemia (IIH) is characterized by severe hypercalcemia with failure to thrive, vomiting, dehydration, and nephrocalcinosis. Recently, mutations in the vitamin D catabolizing enzyme 25-hydroxyvitamin D3-24-hydroxylase (CYP24A1) were described that lead to increased sensitivity to vitamin D due to accumulation of the active metabolite 1,25-(OH)2D3. In a subgroup of patients who presented in early infancy with renal phosphate wasting and symptomatic hypercalcemia, mutations in CYP24A1 were excluded. Four patients from families with parental consanguinity were subjected to homozygosity mapping that identified a second IIH gene locus on chromosome 5q35 with a maximum logarithm of odds (LOD) score of 6.79. The sequence analysis of the most promising candidate gene, SLC34A1 encoding renal sodium-phosphate cotransporter 2A (NaPi-IIa), revealed autosomal-recessive mutations in the four index cases and in 12 patients with sporadic IIH. Functional studies of mutant NaPi-IIa in Xenopus oocytes and opossum kidney (OK) cells demonstrated disturbed trafficking to the plasma membrane and loss of phosphate transport activity. Analysis of calcium and phosphate metabolism in Slc34a1-knockout mice highlighted the effect of phosphate depletion and fibroblast growth factor-23 suppression on the development of the IIH phenotype. The human and mice data together demonstrate that primary renal phosphate wasting caused by defective NaPi-IIa function induces inappropriate production of 1,25-(OH)2D3 with subsequent symptomatic hypercalcemia. Clinical and laboratory findings persist despite cessation of vitamin D prophylaxis but rapidly respond to phosphate supplementation. Therefore, early differentiation between SLC34A1 (NaPi-IIa) and CYP24A1 (24-hydroxylase) defects appears critical for targeted therapy in patients with IIH. PMID:26047794

  10. 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

  11. Identification of a novel nonsense mutation in RP1 that causes autosomal recessive retinitis pigmentosa in an Indonesian family

    PubMed Central

    Siemiatkowska, Anna M.; Astuti, Galuh D.N.; Arimadyo, Kentar; den Hollander, Anneke I.; Faradz, Sultana M.H.; Cremers, Frans P.M.

    2012-01-01

    Purpose The purpose of this study was to identify the underlying molecular genetic defect in an Indonesian family with three affected individuals who had received a diagnosis of retinitis pigmentosa (RP). Methods Clinical evaluation of the family members included measuring visual acuity and fundoscopy, and assessing visual field and color vision. Genomic DNA of the three affected individuals was analyzed with Illumina 700k single nucleotide polymorphism (SNP) arrays, and homozygous regions were identified using PLINK software. Mutation analysis was performed with sequence analysis of the retinitis pigmentosa 1 (RP1) gene that resided in one of the homozygous regions. The frequency of the identified mutation in the Indonesian population was determined with TaqI restriction fragment length polymorphism analysis. Results A novel homozygous nonsense mutation in exon 4 of the RP1 gene, c.1012C>T (p.R338*), was identified in the proband and her two affected sisters. Unaffected family members either carried two wild-type alleles or were heterozygous carriers of the mutation. The mutation was not present in 184 Indonesian control samples. Conclusions Most of the previously reported RP1 mutations are inherited in an autosomal dominant mode, and appear to cluster in exon 4. Here, we identified a novel homozygous p.R338* mutation in exon 4 of RP1, and speculate on the mutational mechanisms of different RP1 mutations underlying dominant and recessive RP. PMID:23077400

  12. Mutations in PTPRQ are a cause of autosomal-recessive nonsyndromic hearing impairment DFNB84 and associated with vestibular dysfunction.

    PubMed

    Schraders, Margit; Oostrik, Jaap; Huygen, Patrick L M; Strom, Tim M; van Wijk, Erwin; Kunst, Henricus P M; Hoefsloot, Lies H; Cremers, Cor W R J; Admiraal, Ronald J C; Kremer, Hannie

    2010-04-01

    We identified overlapping homozygous regions within the DFNB84 locus in a nonconsanguineous Dutch family and a consanguineous Moroccan family with sensorineural autosomal-recessive nonsyndromic hearing impairment (arNSHI). The critical region of 3.17 Mb harbored the PTPRQ gene and mouse models with homozygous mutations in the orthologous gene display severe hearing loss. We show that the human PTPRQ gene was not completely annotated and that additional, alternatively spliced exons are present at the 5' end of the gene. Different PTPRQ isoforms are encoded with a varying number of fibronectin type 3 (FN3) domains, a transmembrane domain, and a phosphatase domain. Sequence analysis of the PTPRQ gene in members of the families revealed a nonsense mutation in the Dutch family and a missense mutation in the Moroccan family. The missense mutation is located in one of the FN3 domains. The nonsense mutation results in a truncated protein with only a small number of FN3 domains and no transmembrane or phosphatase domain. Hearing loss in the patients with PTPRQ mutations is likely to be congenital and moderate to profound and most severe in the family with the nonsense mutation. Progression of the hearing loss was observed in both families. The hearing loss is accompanied by vestibular dysfunction in all affected individuals. Although we show that PTPRQ is expressed in many tissues, no symptoms other than deafness were observed in the patients. PMID:20346435

  13. Recessively inherited L-DOPA-responsive dystonia caused by a point mutation (Q381K) in the tyrosine hydroxylase gene.

    PubMed

    Knappskog, P M; Flatmark, T; Mallet, J; Lüdecke, B; Bartholomé, K

    1995-07-01

    Tyrosine hydroxylase (TH) catalyzes the conversion of L-tyrosine to L-dihydroxyphenylalanine (L-DOPA), the rate-limiting step in the biosynthesis of dopamine. Recently, we described a point mutation in hTH (Q381K) in a family of two siblings suffering from progressive L-DOPA-responsive dystonia (DRD), representing the first reported mutation in this gene. We here describe the cloning, expression and steady-state kinetic properties of the recombinant mutant enzyme. When expressed by a coupled in vitro transcription-translation system and in E. coli, the mutant enzyme represents a kinetic variant form, with a reduced affinity for L-tyrosine. The 'residual activity' of about 15% of the corresponding wild-type hTH (isoform hTH1), at substrate concentrations prevailing in vivo, is compatible with the clinical phenotype of the two Q381K homozygote patients carrying this recessively inherited mutation. PMID:8528210

  14. 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. PMID:26246154

  15. A novel missense mutation p.L76P in the GJB2 gene causing nonsyndromic recessive deafness in a Brazilian family.

    PubMed

    Batissoco, A C; Auricchio, M T B M; Kimura, L; Tabith-Junior, A; Mingroni-Netto, R C

    2009-02-01

    Mutations in the GJB2 gene, encoding connexin 26 (Cx26), are a major cause of nonsyndromic recessive hearing loss in many countries. We report here on a novel point mutation in GJB2, p.L76P (c.227C>T), in compound heterozygosity with a c.35delG mutation, in two Brazilian sibs, one presenting mild and the other profound nonsyndromic neurosensorial hearing impairment. Their father, who carried a wild-type allele and a p.L76P mutation, had normal hearing. The mutation leads to the substitution of leucine (L) by proline (P) at residue 76, an evolutionarily conserved position in Cx26 as well as in other connexins. This mutation is predicted to affect the first extracellular domain (EC1) or the second transmembrane domain (TM2). EC1 is important for connexon-connexon interaction and for the control of channel voltage gating. The segregation of the c.227C>T (p.L76P) mutation together with c.35delG in this family indicates a recessive mode of inheritance. The association between the p.L76P mutation and hearing impairment is further supported by its absence in a normal hearing control group of 100 individuals, 50 European-Brazilians and 50 African-Brazilians. PMID:19274344

  16. Recessive mutations in SLC13A5 result in a loss of citrate transport and cause neonatal epilepsy, developmental delay and teeth hypoplasia.

    PubMed

    Hardies, Katia; de Kovel, Carolien G F; Weckhuysen, Sarah; Asselbergh, Bob; Geuens, Thomas; Deconinck, Tine; Azmi, Abdelkrim; May, Patrick; Brilstra, Eva; Becker, Felicitas; Barisic, Nina; Craiu, Dana; Braun, Kees P J; Lal, Dennis; Thiele, Holger; Schubert, Julian; Weber, Yvonne; van 't Slot, Ruben; Nürnberg, Peter; Balling, Rudi; Timmerman, Vincent; Lerche, Holger; Maudsley, Stuart; Helbig, Ingo; Suls, Arvid; Koeleman, Bobby P C; De Jonghe, Peter

    2015-11-01

    The epileptic encephalopathies are a clinically and aetiologically heterogeneous subgroup of epilepsy syndromes. Most epileptic encephalopathies have a genetic cause and patients are often found to carry a heterozygous de novo mutation in one of the genes associated with the disease entity. Occasionally recessive mutations are identified: a recent publication described a distinct neonatal epileptic encephalopathy (MIM 615905) caused by autosomal recessive mutations in the SLC13A5 gene. Here, we report eight additional patients belonging to four different families with autosomal recessive mutations in SLC13A5. SLC13A5 encodes a high affinity sodium-dependent citrate transporter, which is expressed in the brain. Neurons are considered incapable of de novo synthesis of tricarboxylic acid cycle intermediates; therefore they rely on the uptake of intermediates, such as citrate, to maintain their energy status and neurotransmitter production. The effect of all seven identified mutations (two premature stops and five amino acid substitutions) was studied in vitro, using immunocytochemistry, selective western blot and mass spectrometry. We hereby demonstrate that cells expressing mutant sodium-dependent citrate transporter have a complete loss of citrate uptake due to various cellular loss-of-function mechanisms. In addition, we provide independent proof of the involvement of autosomal recessive SLC13A5 mutations in the development of neonatal epileptic encephalopathies, and highlight teeth hypoplasia as a possible indicator for SLC13A5 screening. All three patients who tried the ketogenic diet responded well to this treatment, and future studies will allow us to ascertain whether this is a recurrent feature in this severe disorder. PMID:26384929

  17. Mutations in NR2E3 can cause dominant or recessive retinal degenerations in a same family

    PubMed Central

    Escher, Pascal; Gouras, Peter; Roduit, Raphaël; Tiab, Leila; Bolay, Sylvain; Delarive, Tania; Chen, Shiming; Tsai, Chih-Cheng; Hayashi, Masanori; Zernant, Jana; Merriam, Joanna E.; Mermod, Nicolas; Allikmets, Rando; Munier, Francis L.; Schorderet, Daniel F.

    2013-01-01

    NR2E3 (PNR), a nuclear receptor specifically expressed in photoreceptors, represses cone-specific genes and activates several rod-specific genes. In humans, mutations in NR2E3 have been associated with the recessively inherited enhanced short wavelength sensitive (S-) cone syndrome (ESCS) and, recently, with autosomal dominant retinitis pigmentosa (adRP). In the present work, we describe two additional families affected by adRP that carry a heterozygous c.166G>A (p.G56R) mutation in the NR2E3 gene. Functional analysis determined dominant negative activity of the p.G56R mutant protein as the molecular mechanism of adRP. Interestingly, in one pedigree, the most common causal variant for ESCS (p.R311Q) co-segregated with the adRP-linked p.G56R mutation, and, the compound heterozygotes exhibited an ESCS-like phenotype, which in one of the 2 cases was strikingly “milder” than the patients carrying the p.G56R mutation alone. Impaired repression of cone-specific genes by the corepressors atrophin-1 (dentatorubral-pallidoluysian atrophy DRPLA gene product) and atrophin-2 (RERE repeat protein) appeared to be a molecular mechanism mediating the beneficial effect of the p.R311Q mutation. Finally, the functional dominance of the p.R311Q to the p.G56R mutation is discussed. PMID:19006237

  18. Novel mutations in PIEZO1 cause an autosomal recessive generalized lymphatic dysplasia with non-immune hydrops fetalis

    PubMed Central

    Fotiou, Elisavet; Martin-Almedina, Silvia; Simpson, Michael A.; Lin, Shin; Gordon, Kristiana; Brice, Glen; Atton, Giles; Jeffery, Iona; Rees, David C.; Mignot, Cyril; Vogt, Julie; Homfray, Tessa; Snyder, Michael P.; Rockson, Stanley G.; Jeffery, Steve; Mortimer, Peter S.; Mansour, Sahar; Ostergaard, Pia

    2015-01-01

    Generalized lymphatic dysplasia (GLD) is a rare form of primary lymphoedema characterized by a uniform, widespread lymphoedema affecting all segments of the body, with systemic involvement such as intestinal and/or pulmonary lymphangiectasia, pleural effusions, chylothoraces and/or pericardial effusions. This may present prenatally as non-immune hydrops. Here we report homozygous and compound heterozygous mutations in PIEZO1, resulting in an autosomal recessive form of GLD with a high incidence of non-immune hydrops fetalis and childhood onset of facial and four limb lymphoedema. Mutations in PIEZO1, which encodes a mechanically activated ion channel, have been reported with autosomal dominant dehydrated hereditary stomatocytosis and non-immune hydrops of unknown aetiology. Besides its role in red blood cells, our findings indicate that PIEZO1 is also involved in the development of lymphatic structures. PMID:26333996

  19. Novel mutations in PIEZO1 cause an autosomal recessive generalized lymphatic dysplasia with non-immune hydrops fetalis.

    PubMed

    Fotiou, Elisavet; Martin-Almedina, Silvia; Simpson, Michael A; Lin, Shin; Gordon, Kristiana; Brice, Glen; Atton, Giles; Jeffery, Iona; Rees, David C; Mignot, Cyril; Vogt, Julie; Homfray, Tessa; Snyder, Michael P; Rockson, Stanley G; Jeffery, Steve; Mortimer, Peter S; Mansour, Sahar; Ostergaard, Pia

    2015-01-01

    Generalized lymphatic dysplasia (GLD) is a rare form of primary lymphoedema characterized by a uniform, widespread lymphoedema affecting all segments of the body, with systemic involvement such as intestinal and/or pulmonary lymphangiectasia, pleural effusions, chylothoraces and/or pericardial effusions. This may present prenatally as non-immune hydrops. Here we report homozygous and compound heterozygous mutations in PIEZO1, resulting in an autosomal recessive form of GLD with a high incidence of non-immune hydrops fetalis and childhood onset of facial and four limb lymphoedema. Mutations in PIEZO1, which encodes a mechanically activated ion channel, have been reported with autosomal dominant dehydrated hereditary stomatocytosis and non-immune hydrops of unknown aetiology. Besides its role in red blood cells, our findings indicate that PIEZO1 is also involved in the development of lymphatic structures. PMID:26333996

  20. Mutations in the Alpha 1,2-Mannosidase Gene, MAN1B1, Cause Autosomal-Recessive Intellectual Disability

    PubMed Central

    Rafiq, Muhammad Arshad; Kuss, Andreas W.; Puettmann, Lucia; Noor, Abdul; Ramiah, Annapoorani; Ali, Ghazanfar; Hu, Hao; Kerio, Nadir Ali; Xiang, Yong; Garshasbi, Masoud; Khan, Muzammil Ahmad; Ishak, Gisele E.; Weksberg, Rosanna; Ullmann, Reinhard; Tzschach, Andreas; Kahrizi, Kimia; Mahmood, Khalid; Naeem, Farooq; Ayub, Muhammad; Moremen, Kelley W.; Vincent, John B.; Ropers, Hans Hilger; Ansar, Muhammad; Najmabadi, Hossein

    2011-01-01

    We have used genome-wide genotyping to identify an overlapping homozygosity-by-descent locus on chromosome 9q34.3 (MRT15) in four consanguineous families affected by nonsyndromic autosomal-recessive intellectual disability (NS-ARID) and one in which the patients show additional clinical features. Four of the families are from Pakistan, and one is from Iran. Using a combination of next-generation sequencing and Sanger sequencing, we have identified mutations in the gene MAN1B1, encoding a mannosyl oligosaccharide, alpha 1,2-mannosidase. In one Pakistani family, MR43, a homozygous nonsense mutation (RefSeq number NM_016219.3: c.1418G>A [p.Trp473∗]), segregated with intellectual disability and additional dysmorphic features. We also identified the missense mutation c. 1189G>A (p.Glu397Lys; RefSeq number NM_016219.3), which segregates with NS-ARID in three families who come from the same village and probably have shared inheritance. In the Iranian family, the missense mutation c.1000C>T (p.Arg334Cys; RefSeq number NM_016219.3) also segregates with NS-ARID. Both missense mutations are at amino acid residues that are conserved across the animal kingdom, and they either reduce kcat by ∼1300-fold or disrupt stable protein expression in mammalian cells. MAN1B1 is one of the few NS-ARID genes with an elevated mutation frequency in patients with NS-ARID from different populations. PMID:21763484

  1. 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

  2. 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

  3. 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. PMID:23860047

  4. 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

  5. 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

  6. [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

  7. 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

  8. Loss-of-Function Alanyl-tRNA Synthetase Mutations Cause an Autosomal-Recessive Early-Onset Epileptic Encephalopathy with Persistent Myelination Defect

    PubMed Central

    Simons, Cas; Griffin, Laurie B.; Helman, Guy; Golas, Gretchen; Pizzino, Amy; Bloom, Miriam; Murphy, Jennifer L.P.; Crawford, Joanna; Evans, Sarah H.; Topper, Scott; Whitehead, Matthew T.; Schreiber, John M.; Chapman, Kimberly A.; Tifft, Cyndi; Lu, Katrina B.; Gamper, Howard; Shigematsu, Megumi; Taft, Ryan J.; Antonellis, Anthony; Hou, Ya-Ming; Vanderver, Adeline

    2015-01-01

    Mutations in genes encoding aminoacyl-tRNA synthetases are known to cause leukodystrophies and genetic leukoencephalopathies—heritable disorders that result in white matter abnormalities in the central nervous system. Here we report three individuals (two siblings and an unrelated individual) with severe infantile epileptic encephalopathy, clubfoot, absent deep tendon reflexes, extrapyramidal symptoms, and persistently deficient myelination on MRI. Analysis by whole exome sequencing identified mutations in the nuclear-encoded alanyl-tRNA synthetase (AARS) in these two unrelated families: the two affected siblings are compound heterozygous for p.Lys81Thr and p.Arg751Gly AARS, and the single affected child is homozygous for p.Arg751Gly AARS. The two identified mutations were found to result in a significant reduction in function. Mutations in AARS were previously associated with an autosomal-dominant inherited form of axonal neuropathy, Charcot-Marie-Tooth disease type 2N (CMT2N). The autosomal-recessive AARS mutations identified in the individuals described here, however, cause a severe infantile epileptic encephalopathy with a central myelin defect and peripheral neuropathy, demonstrating that defects of alanyl-tRNA charging can result in a wide spectrum of disease manifestations. PMID:25817015

  9. Loss-of-function alanyl-tRNA synthetase mutations cause an autosomal-recessive early-onset epileptic encephalopathy with persistent myelination defect.

    PubMed

    Simons, Cas; Griffin, Laurie B; Helman, Guy; Golas, Gretchen; Pizzino, Amy; Bloom, Miriam; Murphy, Jennifer L P; Crawford, Joanna; Evans, Sarah H; Topper, Scott; Whitehead, Matthew T; Schreiber, John M; Chapman, Kimberly A; Tifft, Cyndi; Lu, Katrina B; Gamper, Howard; Shigematsu, Megumi; Taft, Ryan J; Antonellis, Anthony; Hou, Ya-Ming; Vanderver, Adeline

    2015-04-01

    Mutations in genes encoding aminoacyl-tRNA synthetases are known to cause leukodystrophies and genetic leukoencephalopathies-heritable disorders that result in white matter abnormalities in the central nervous system. Here we report three individuals (two siblings and an unrelated individual) with severe infantile epileptic encephalopathy, clubfoot, absent deep tendon reflexes, extrapyramidal symptoms, and persistently deficient myelination on MRI. Analysis by whole exome sequencing identified mutations in the nuclear-encoded alanyl-tRNA synthetase (AARS) in these two unrelated families: the two affected siblings are compound heterozygous for p.Lys81Thr and p.Arg751Gly AARS, and the single affected child is homozygous for p.Arg751Gly AARS. The two identified mutations were found to result in a significant reduction in function. Mutations in AARS were previously associated with an autosomal-dominant inherited form of axonal neuropathy, Charcot-Marie-Tooth disease type 2N (CMT2N). The autosomal-recessive AARS mutations identified in the individuals described here, however, cause a severe infantile epileptic encephalopathy with a central myelin defect and peripheral neuropathy, demonstrating that defects of alanyl-tRNA charging can result in a wide spectrum of disease manifestations. PMID:25817015

  10. A founder mutation in COL4A3 causes autosomal recessive Alport syndrome in the Ashkenazi Jewish population.

    PubMed

    Webb, B D; Brandt, T; Liu, L; Jalas, C; Liao, J; Fedick, A; Linderman, M D; Diaz, G A; Kornreich, R; Trachtman, H; Mehta, L; Edelmann, L

    2014-08-01

    Alport syndrome is an inherited progressive nephropathy arising from mutations in the type IV collagen genes, COL4A3, COL4A4, and COL4A5. Symptoms also include sensorineural hearing loss and ocular lesions. We determined the molecular basis of Alport syndrome in a non-consanguineous Ashkenazi Jewish family with multiple affected females using linkage analysis and next generation sequencing. We identified a homozygous COL4A3 mutation, c.40_63del, in affected individuals with mutant alleles inherited from each parent on partially conserved haplotypes. Large-scale population screening of 2017 unrelated Ashkenazi Jewish samples revealed a carrier frequency of 1 in 183 indicating that COL4A3 c.40_63del is a founder mutation which may be a common cause of Alport syndrome in this population. Additionally, we determined that heterozygous mutation carriers in this family do not meet criteria for a diagnosis of Thin Basement Membrane Nephropathy and concluded that carriers of c.40_63del are not likely to develop benign familial hematuria. PMID:23927549

  11. 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. PMID:27132592

  12. Targeted next generation sequencing identifies novel mutations in RP1 as a relatively common cause of autosomal recessive rod-cone dystrophy.

    PubMed

    El Shamieh, Said; Boulanger-Scemama, Elise; Lancelot, Marie-Elise; Antonio, Aline; Démontant, Vanessa; Condroyer, Christel; Letexier, Mélanie; Saraiva, Jean-Paul; Mohand-Saïd, Saddek; Sahel, José-Alain; Audo, Isabelle; Zeitz, Christina

    2015-01-01

    We report ophthalmic and genetic findings in families with autosomal recessive rod-cone dystrophy (arRCD) and RP1 mutations. Detailed ophthalmic examination was performed in 242 sporadic and arRCD subjects. Genomic DNA was investigated using our customized next generation sequencing panel targeting up to 123 genes implicated in inherited retinal disorders. Stringent filtering coupled with Sanger sequencing and followed by cosegregation analysis was performed to confirm biallelism and the implication of the most likely disease causing variants. Sequencing identified 9 RP1 mutations in 7 index cases. Eight of the mutations were novel, and all cosegregated with severe arRCD phenotype, found associated with additional macular changes. Among the identified mutations, 4 belong to a region, previously associated with arRCD, and 5 others in a region previously associated with adRCD. Our prevalence studies showed that RP1 mutations account for up to 2.5% of arRCD. These results point out for the necessity of sequencing RP1 when genetically investigating sporadic and arRCD. It further highlights the interest of unbiased sequencing technique, which allows investigating the implication of the same gene in different modes of inheritance. Finally, it reports that different regions of RP1 can also lead to arRCD. PMID:25692139

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

    PubMed Central

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

    2010-01-01

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

  14. Recessive mutations in the putative calcium-activated chloride channel Anoctamin 5 cause proximal LGMD2L and distal MMD3 muscular dystrophies.

    PubMed

    Bolduc, Véronique; Marlow, Gareth; Boycott, Kym M; Saleki, Khalil; Inoue, Hiroshi; Kroon, Johan; Itakura, Mitsuo; Robitaille, Yves; Parent, Lucie; Baas, Frank; Mizuta, Kuniko; Kamata, Nobuyuki; Richard, Isabelle; Linssen, Wim H J P; Mahjneh, Ibrahim; de Visser, Marianne; Bashir, Rumaisa; Brais, Bernard

    2010-02-12

    The recently described human anion channel Anoctamin (ANO) protein family comprises at least ten members, many of which have been shown to correspond to calcium-activated chloride channels. To date, the only reported human mutations in this family of genes are dominant mutations in ANO5 (TMEM16E, GDD1) in the rare skeletal disorder gnathodiaphyseal dysplasia. We have identified recessive mutations in ANO5 that result in a proximal limb-girdle muscular dystrophy (LGMD2L) in three French Canadian families and in a distal non-dysferlin Miyoshi myopathy (MMD3) in Dutch and Finnish families. These mutations consist of a splice site, one base pair duplication shared by French Canadian and Dutch cases, and two missense mutations. The splice site and the duplication mutations introduce premature-termination codons and consequently trigger nonsense-mediated mRNA decay, suggesting an underlining loss-of-function mechanism. The LGMD2L phenotype is characterized by proximal weakness, with prominent asymmetrical quadriceps femoris and biceps brachii atrophy. The MMD3 phenotype is associated with distal weakness, of calf muscles in particular. With the use of electron microscopy, multifocal sarcolemmal lesions were observed in both phenotypes. The phenotypic heterogeneity associated with ANO5 mutations is reminiscent of that observed with Dysferlin (DYSF) mutations that can cause both LGMD2B and Miyoshi myopathy (MMD1). In one MMD3-affected individual, defective membrane repair was documented on fibroblasts by membrane-resealing ability assays, as observed in dysferlinopathies. Though the function of the ANO5 protein is still unknown, its putative calcium-activated chloride channel function may lead to important insights into the role of deficient skeletal muscle membrane repair in muscular dystrophies. PMID:20096397

  15. Recessive Mutations in the Putative Calcium-Activated Chloride Channel Anoctamin 5 Cause Proximal LGMD2L and Distal MMD3 Muscular Dystrophies

    PubMed Central

    Bolduc, Véronique; Marlow, Gareth; Boycott, Kym M.; Saleki, Khalil; Inoue, Hiroshi; Kroon, Johan; Itakura, Mitsuo; Robitaille, Yves; Parent, Lucie; Baas, Frank; Mizuta, Kuniko; Kamata, Nobuyuki; Richard, Isabelle; Linssen, Wim H.J.P.; Mahjneh, Ibrahim; de Visser, Marianne; Bashir, Rumaisa; Brais, Bernard

    2010-01-01

    The recently described human anion channel Anoctamin (ANO) protein family comprises at least ten members, many of which have been shown to correspond to calcium-activated chloride channels. To date, the only reported human mutations in this family of genes are dominant mutations in ANO5 (TMEM16E, GDD1) in the rare skeletal disorder gnathodiaphyseal dysplasia. We have identified recessive mutations in ANO5 that result in a proximal limb-girdle muscular dystrophy (LGMD2L) in three French Canadian families and in a distal non-dysferlin Miyoshi myopathy (MMD3) in Dutch and Finnish families. These mutations consist of a splice site, one base pair duplication shared by French Canadian and Dutch cases, and two missense mutations. The splice site and the duplication mutations introduce premature-termination codons and consequently trigger nonsense-mediated mRNA decay, suggesting an underlining loss-of-function mechanism. The LGMD2L phenotype is characterized by proximal weakness, with prominent asymmetrical quadriceps femoris and biceps brachii atrophy. The MMD3 phenotype is associated with distal weakness, of calf muscles in particular. With the use of electron microscopy, multifocal sarcolemmal lesions were observed in both phenotypes. The phenotypic heterogeneity associated with ANO5 mutations is reminiscent of that observed with Dysferlin (DYSF) mutations that can cause both LGMD2B and Miyoshi myopathy (MMD1). In one MMD3-affected individual, defective membrane repair was documented on fibroblasts by membrane-resealing ability assays, as observed in dysferlinopathies. Though the function of the ANO5 protein is still unknown, its putative calcium-activated chloride channel function may lead to important insights into the role of deficient skeletal muscle membrane repair in muscular dystrophies. PMID:20096397

  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. PMID:27040692

  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. PMID:24951542

  18. 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. PMID:27259055

  19. 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

  20. 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

  1. 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

  2. Mutation in Exon 1f of PLEC, Leading to Disruption of Plectin Isoform 1f, Causes Autosomal-Recessive Limb-Girdle Muscular Dystrophy

    PubMed Central

    Gundesli, Hulya; Talim, Beril; Korkusuz, Petek; Balci-Hayta, Burcu; Cirak, Sebahattin; Akarsu, Nurten A.; Topaloglu, Haluk; Dincer, Pervin

    2010-01-01

    Limb-girdle muscular dystrophy (LGMD) is a genetically heterogeneous group of inherited muscular disorders manifesting symmetric, proximal, and slowly progressive muscle weakness. Using Affymetrix 250K SNP Array genotyping and homozygosity mapping, we mapped an autosomal-recessive LGMD phenotype to the telomeric portion of chromosome 8q in a consanguineous Turkish family with three affected individuals. DNA sequence analysis of PLEC identified a homozygous c.1_9del mutation containing an initiation codon in exon 1f, which is an isoform-specific sequence of plectin isoform 1f. The same homozygous mutation was also detected in two additional families during the analysis of 72 independent LGMD2-affected families. Moreover, we showed that the expression of PLEC was reduced in the patient's muscle and that there was almost no expression for plectin 1f mRNA as a result of the mutation. In addition to dystrophic changes in muscle, ultrastructural alterations, such as membrane duplications, an enlarged space between the membrane and sarcomere, and misalignment of Z-disks, were observed by transmission electron microscopy. Unlike the control skeletal muscle, no sarcolemmal staining of plectin was detected in the patient's muscle. We conclude that as a result of plectin 1f deficiency, the linkage between the sarcolemma and sarcomere is broken, which could affect the structural organization of the myofiber. Our data show that one of the isoforms of plectin plays a key role in skeletal muscle function and that disruption of the plectin 1f can cause the LGMD2 phenotype without any dermatologic component as was previously reported with mutations in constant exons of PLEC. PMID:21109228

  3. Adenylate cyclase 1 (ADCY1) mutations cause recessive hearing impairment in humans and defects in hair cell function and hearing in zebrafish

    PubMed Central

    Santos-Cortez, Regie Lyn P.; Lee, Kwanghyuk; Giese, Arnaud P.; Ansar, Muhammad; Amin-Ud-Din, Muhammad; Rehn, Kira; Wang, Xin; Aziz, Abdul; Chiu, Ilene; Hussain Ali, Raja; Smith, Joshua D.; Shendure, Jay; Bamshad, Michael; Nickerson, Deborah A.; Ahmed, Zubair M.; Ahmad, Wasim; Riazuddin, Saima; Leal, Suzanne M.

    2014-01-01

    Cyclic AMP (cAMP) production, which is important for mechanotransduction within the inner ear, is catalyzed by adenylate cyclases (AC). However, knowledge of the role of ACs in hearing is limited. Previously, a novel autosomal recessive non-syndromic hearing impairment locus DFNB44 was mapped to chromosome 7p14.1-q11.22 in a consanguineous family from Pakistan. Through whole-exome sequencing of DNA samples from hearing-impaired family members, a nonsense mutation c.3112C>T (p.Arg1038*) within adenylate cyclase 1 (ADCY1) was identified. This stop-gained mutation segregated with hearing impairment within the family and was not identified in ethnically matched controls or within variant databases. This mutation is predicted to cause the loss of 82 amino acids from the carboxyl tail, including highly conserved residues within the catalytic domain, plus a calmodulin-stimulation defect, both of which are expected to decrease enzymatic efficiency. Individuals who are homozygous for this mutation had symmetric, mild-to-moderate mixed hearing impairment. Zebrafish adcy1b morphants had no FM1-43 dye uptake and lacked startle response, indicating hair cell dysfunction and gross hearing impairment. In the mouse, Adcy1 expression was observed throughout inner ear development and maturation. ADCY1 was localized to the cytoplasm of supporting cells and hair cells of the cochlea and vestibule and also to cochlear hair cell nuclei and stereocilia. Ex vivo studies in COS-7 cells suggest that the carboxyl tail of ADCY1 is essential for localization to actin-based microvilli. These results demonstrate that ADCY1 has an evolutionarily conserved role in hearing and that cAMP signaling is important to hair cell function within the inner ear. PMID:24482543

  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. 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

  6. 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

  7. 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

  8. Recessive and dominant mutations in COL12A1 cause a novel EDS/myopathy overlap syndrome in humans and mice

    PubMed Central

    Zou, Yaqun; Zwolanek, Daniela; Izu, Yayoi; Gandhy, Shreya; Schreiber, Gudrun; Brockmann, Knut; Devoto, Marcella; Tian, Zuozhen; Hu, Ying; Veit, Guido; Meier, Markus; Stetefeld, Jörg; Hicks, Debbie; Straub, Volker; Voermans, Nicol C.; Birk, David E.; Barton, Elisabeth R.; Koch, Manuel; Bönnemann, Carsten G.

    2014-01-01

    Collagen VI-related myopathies are disorders of connective tissue presenting with an overlap phenotype combining clinical involvement from the muscle and from the connective tissue. Not all patients displaying related overlap phenotypes between muscle and connective tissue have mutations in collagen VI. Here, we report a homozygous recessive loss of function mutation and a de novo dominant mutation in collagen XII (COL12A1) as underlying a novel overlap syndrome involving muscle and connective tissue. Two siblings homozygous for a loss of function mutation showed widespread joint hyperlaxity combined with weakness precluding independent ambulation, while the patient with the de novo missense mutation was more mildly affected, showing improvement including the acquisition of walking. A mouse model with inactivation of the Col12a1 gene showed decreased grip strength, a delay in fiber-type transition and a deficiency in passive force generation while the muscle seems more resistant to eccentric contraction induced force drop, indicating a role for a matrix-based passive force-transducing elastic element in the generation of the weakness. This new muscle connective tissue overlap syndrome expands on the emerging importance of the muscle extracellular matrix in the pathogenesis of muscle disease. PMID:24334604

  9. CRTAP AND LEPRE1 MUTATIONS IN RECESSIVE OSTEOGENESIS IMPERFECTA

    PubMed Central

    Baldridge, Dustin; Schwarze, Ulrike; Morello, Roy; Lennington, Jennifer; Bertin, Terry K.; Pace, James M.; Pepin, Melanie G.; Weis, MaryAnn; Eyre, David R.; Walsh, Jennifer; Lambert, Deborah; Green, Andrew; Robinson, Haynes; Michelson, Melonie; Houge, Gunnar; Lindman, Carl; Martin, Judith; Ward, Jewell; Lemyre, Emmanuelle; Mitchell, John J.; Krakow, Deborah; Rimoin, David L.; Cohn, Daniel H.; Byers, Peter H.; Lee, Brendan

    2009-01-01

    Autosomal dominant osteogenesis imperfecta (OI) is caused by mutations in the genes (COL1A1 or COL1A2) encoding the chains of type I collagen. Recently, dysregulation of hydroxylation of a single proline residue at position 986 of both the triple-helical domains of type I collagen α1(I) and type II collagen α1(II) chains has been implicated in the pathogenesis of recessive forms of OI. Two proteins, CRTAP, or cartilage-associated protein, and prolyl-3-hydroxylase-1 (P3H1, encoded by the LEPRE1 gene) form a complex that performs the hydroxylation and brings the prolyl cis-trans isomerase cyclophilin-B (CYPB) to the unfolded collagen. In our screen of 78 subjects diagnosed with OI type II or III, we identified three probands with mutations in CRTAP and sixteen with mutations in LEPRE1. The latter group includes a mutation in patients from the Irish Traveller population, a genetically isolated community with increased incidence of OI. The clinical features resulting from CRTAP or LEPRE1 loss of function mutations were difficult to distinguish at birth. Infants in both groups had multiple fractures, decreased bone modeling (affecting especially the femurs), and extremely low bone mineral density. Interestingly, “popcorn” epiphyses may reflect underlying cartilaginous and bone dysplasia in this form of OI. These results expand the range of CRTAP/LEPRE1 mutations that result in recessive OI and emphasize the importance of distinguishing recurrence of severe OI of recessive inheritance from those that result from parental germline mosaicism for COL1A1 or COL1A2 mutations. PMID:18566967

  10. 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

  11. 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

  12. Biallelic Truncating Mutations in FMN2, Encoding the Actin-Regulatory Protein Formin 2, Cause Nonsyndromic Autosomal-Recessive Intellectual Disability

    PubMed Central

    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.

    2014-01-01

    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. PMID:25480035

  13. Recessive Mutations in the Gene Encoding the Tight Junction Protein Occludin Cause Band-like Calcification with Simplified Gyration and Polymicrogyria

    PubMed Central

    O'Driscoll, Mary C.; Daly, Sarah B.; Urquhart, Jill E.; Black, Graeme C.M.; Pilz, Daniela T.; Brockmann, Knut; McEntagart, Meriel; Abdel-Salam, Ghada; Zaki, Maha; Wolf, Nicole I.; Ladda, Roger L.; Sell, Susan; D'Arrigo, Stefano; Squier, Waney; Dobyns, William B.; Livingston, John H.; Crow, Yanick J.

    2010-01-01

    Band-like calcification with simplified gyration and polymicrogyria (BLC-PMG) is a rare autosomal-recessive neurological disorder showing highly characteristic clinical and neuroradiological features. Affected individuals demonstrate early-onset seizures, severe microcephaly, and developmental arrest with bilateral, symmetrical polymicrogyria (PMG) and a band of gray matter calcification on brain imaging; as such, the disorder can be considered as a “pseudo-TORCH” syndrome. By using autozygosity mapping and copy number analysis we identified intragenic deletions and mutations in OCLN in nine patients from six families with BLC-PMG. The OCLN gene encodes occludin, an integral component of tight junctions. Neuropathological analysis of an affected individual showed similarity to the mouse model of occludin deficiency with calcification predominantly associated with blood vessels. Both intracranial calcification and PMG are heterogeneous in etiology. Neuropathological and clinical studies of PMG have suggested that in utero ischemic or vascular insults may contribute to this common cortical abnormality. Tight junctions are functional in cerebral blood vessels early in fetal development and continue to play a vital role in maintenance of the blood-brain barrier during postnatal life. We provide evidence that the tight junction protein occludin (encoded by the OCLN gene) is involved in the pathogenesis of malformations of cortical development. PMID:20727516

  14. 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

  15. A recessive syndrome of intellectual disability, moderate overgrowth, and renal dysplasia predisposing to Wilms tumor is caused by a mutation in FIBP gene.

    PubMed

    Akawi, Nadia; Ben-Salem, Salma; Lahti, Laura; Partanen, Juha; Ali, Bassam R; Al-Gazali, Lihadh

    2016-08-01

    Clinical classification of overgrowth syndromes represents a challenge since a wide spectrum of disorders result in marked overgrowth. Therefore, there is a continuous effort to identify the genetic basis of these disorders that will eventually facilitate their molecular classification. Here, we have identified the genetic etiology and the pathogenetic mechanism underlying a rare autosomal recessive overgrowth syndrome in three affected siblings. The overgrowth phenotype in the patients was accompanied by developmental delay, learning disabilities, and variable congenital abnormalities. To elucidate the genetic etiology of the disorder, whole-genome genotyping and whole-exome sequencing were used. The disease was mapped to 3p21.1-p14.2 and 11q13.1-q13.4, where an in-frame insertion (c.175_176insTAA) in FIBP gene was revealed. The resulting indel (p.H59LN) was predicted to change the protein conformation with likely deleterious effect on its function as one of the fibroblast growth factor signaling mediators. In vitro cellular proliferation assay and in situ hypridization in vivo were then performed to understand the pathophysiology of the disease. The patients' skin fibroblasts showed an increased proliferation capacity compared to the controls' explaining the observed overgrowth phenotype. In addition, we detected Fibp expression most notably in the brains of mice embryos suggesting a possible effect on cognitive functions early in development. To date, only one patient has been reported with a homozygous nonsense mutation in FIBP exhibiting an overgrowth syndrome with multiple congenital abnormalities. Taken all together, these findings provide convincing evidence implicating FIBP aberrations in the newly recognized overgrowth syndrome and expand the associated phenotypes to include possible Wilms tumor predisposition. © 2016 Wiley Periodicals, Inc. PMID:27183861

  16. Thymidine phosphorylase deficiency causes MNGIE: an autosomal recessive mitochondrial disorder.

    PubMed

    Hirano, M; Martí, R; Spinazzola, A; Nishino, I; Nishigaki, Y

    2004-10-01

    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder caused by mutations in the gene encoding thymidine phosphorylase (TP). The disease is characterized clinically by impaired eye movements, gastrointestinal dysmotility, cachexia, peripheral neuropathy, myopathy, and leukoencephalopathy. Molecular genetic studies of MNGIE patients' tissues have revealed multiple deletions, depletion, and site-specific point mutations of mitochondrial DNA. TP is a cytosolic enzyme required for nucleoside homeostasis. In MNGIE, TP activity is severely reduced and consequently levels of thymidine and deoxyuridine in plasma are dramatically elevated. We have hypothesized that the increased levels of intracellular thymidine and deoxyuridine cause imbalances of mitochondrial nucleotide pools that, in turn, lead to the mtDNA abnormalities. MNGIE was the first molecularly characterized genetic disorder caused by abnormal mitochondrial nucleoside/nucleotide metabolism. Future studies are likely to reveal further insight into this expanding group of diseases. PMID:15571233

  17. Deficient T Cell Receptor Excision Circles (TRECs) in autosomal recessive hyper IgE syndrome caused by DOCK8 mutation: implications for pathogenesis and potential detection by newborn screening.

    PubMed

    Dasouki, Majed; Okonkwo, Kingsley C; Ray, Abhishek; Folmsbeel, Caspian K; Gozales, Diana; Keles, Sevgi; Puck, Jennifer M; Chatila, Talal

    2011-11-01

    Loss of function of DOCK8 is the major cause of autosomal recessive hyper IgE syndrome, a primary immunodeficiency with adaptive and innate immune dysfunction. Patients affected with ARHIES have atopic dermatitis and recurrent, potentially life-threatening viral and bacterial infections. Three consanguineous Pakistani siblings presented with severe atopic dermatitis and superinfection. Direct sequencing of DOCK8 in all three affected siblings demonstrated homozygosity for a deleterious, novel exon 14 frame shift mutation. Current newborn screening for severe combined immunodeficiency syndrome (SCID) and related T cell disorders relies on the quantitation of T Cell Receptor Excision Cells (TRECs) in dried blood spots (DBS). Significantly, both older affected siblings had undetectable TRECs, and TREC copy number was reduced in the youngest sibling. These findings suggest that AR-HIES may be detected by TREC newborn screening, and this diagnosis should be considered in the evaluation of newborns with abnormal TRECs who do not have typical SCID. PMID:21763205

  18. Mutations in WDR62 gene in Pakistani families with autosomal recessive primary microcephaly

    PubMed Central

    2011-01-01

    Background Autosomal recessive primary microcephaly is a disorder of neurogenic mitosis that causes reduction in brain size. It is a rare heterogeneous condition with seven causative genes reported to date. Mutations in WD repeat protein 62 are associated with autosomal recessive primary microcephaly with cortical malformations. This study was initiated to screen WDR62 mutations in four consanguineous Pakistani families with autosomal recessive primary microcephaly. Methods As part of a large study to detect the genetic basis of primary microcephaly in Pakistan, homozygosity mapping and DNA sequencing was used to explore the genetic basis of autosomal recessive primary microcephaly in four families. Results Four out of 100 families recruited in the study revealed linkage to the MCPH2 locus on chromosome 19, which harbor WDR62 gene. DNA sequencing in these MCPH2 linked families result in the identification of a novel nonsense mutation (p.Q648X) and three previously known mutations. Conclusion Our data indicate that WDR62 mutations cause about 4% of autosomal recessive primary microcephaly in Pakistan. PMID:21961505

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

    PubMed Central

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

    2013-01-01

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

  20. A recessive mutation in the APP gene with dominant-negative effect on amyloidogenesis.

    PubMed

    Di Fede, Giuseppe; Catania, Marcella; Morbin, Michela; Rossi, Giacomina; Suardi, Silvia; Mazzoleni, Giulia; Merlin, Marco; Giovagnoli, Anna Rita; Prioni, Sara; Erbetta, Alessandra; Falcone, Chiara; Gobbi, Marco; Colombo, Laura; Bastone, Antonio; Beeg, Marten; Manzoni, Claudia; Francescucci, Bruna; Spagnoli, Alberto; Cantù, Laura; Del Favero, Elena; Levy, Efrat; Salmona, Mario; Tagliavini, Fabrizio

    2009-03-13

    beta-Amyloid precursor protein (APP) mutations cause familial Alzheimer's disease with nearly complete penetrance. We found an APP mutation [alanine-673-->valine-673 (A673V)] that causes disease only in the homozygous state, whereas heterozygous carriers were unaffected, consistent with a recessive Mendelian trait of inheritance. The A673V mutation affected APP processing, resulting in enhanced beta-amyloid (Abeta) production and formation of amyloid fibrils in vitro. Co-incubation of mutated and wild-type peptides conferred instability on Abeta aggregates and inhibited amyloidogenesis and neurotoxicity. The highly amyloidogenic effect of the A673V mutation in the homozygous state and its anti-amyloidogenic effect in the heterozygous state account for the autosomal recessive pattern of inheritance and have implications for genetic screening and the potential treatment of Alzheimer's disease. PMID:19286555

  1. A Recessive Mutation in the APP Gene with Dominant-Negative Effect on Amyloidogenesis

    PubMed Central

    Di Fede, Giuseppe; Catania, Marcella; Morbin, Michela; Rossi, Giacomina; Suardi, Silvia; Mazzoleni, Giulia; Merlin, Marco; Giovagnoli, Anna Rita; Prioni, Sara; Erbetta, Alessandra; Falcone, Chiara; Gobbi, Marco; Colombo, Laura; Bastone, Antonio; Beeg, Marten; Manzoni, Claudia; Francescucci, Bruna; Spagnoli, Alberto; Cantù, Laura; Del Favero, Elena; Levy, Efrat; Salmona, Mario; Tagliavini, Fabrizio

    2009-01-01

    β-Amyloid precursor protein (APP) mutations cause familial Alzheimer’s disease with nearly complete penetrance. We found an APP mutation [alanine-673→valine-673 (A673V)] that causes disease only in the homozygous state, whereas heterozygous carriers were unaffected, consistent with a recessive Mendelian trait of inheritance. The A673V mutation affected APP processing, resulting in enhanced β-amyloid (Aβ) production and formation of amyloid fibrils in vitro. Co-incubation of mutated and wild-type peptides conferred instability on Aβ aggregates and inhibited amyloidogenesis and neurotoxicity. The highly amyloidogenic effect of the A673V mutation in the homozygous state and its anti-amyloidogenic effect in the heterozygous state account for the autosomal recessive pattern of inheritance and have implications for genetic screening and the potential treatment of Alzheimer’s disease. PMID:19286555

  2. Deletions of recessive disease genes: CNV contribution to carrier states and disease-causing alleles

    PubMed Central

    Boone, Philip M.; Campbell, Ian M.; Baggett, Brett C.; Soens, Zachry T.; Rao, Mitchell M.; Hixson, Patricia M.; Patel, Ankita; Bi, Weimin; Cheung, Sau Wai; Lalani, Seema R.; Beaudet, Arthur L.; Stankiewicz, Pawel; Shaw, Chad A.; Lupski, James R.

    2013-01-01

    Over 1200 recessive disease genes have been described in humans. The prevalence, allelic architecture, and per-genome load of pathogenic alleles in these genes remain to be fully elucidated, as does the contribution of DNA copy-number variants (CNVs) to carrier status and recessive disease. We mined CNV data from 21,470 individuals obtained by array-comparative genomic hybridization in a clinical diagnostic setting to identify deletions encompassing or disrupting recessive disease genes. We identified 3212 heterozygous potential carrier deletions affecting 419 unique recessive disease genes. Deletion frequency of these genes ranged from one occurrence to 1.5%. When compared with recessive disease genes never deleted in our cohort, the 419 recessive disease genes affected by at least one carrier deletion were longer and located farther from known dominant disease genes, suggesting that the formation and/or prevalence of carrier CNVs may be affected by both local and adjacent genomic features and by selection. Some subjects had multiple carrier CNVs (307 subjects) and/or carrier deletions encompassing more than one recessive disease gene (206 deletions). Heterozygous deletions spanning multiple recessive disease genes may confer carrier status for multiple single-gene disorders, for complex syndromes resulting from the combination of two or more recessive conditions, or may potentially cause clinical phenotypes due to a multiply heterozygous state. In addition to carrier mutations, we identified homozygous and hemizygous deletions potentially causative for recessive disease. We provide further evidence that CNVs contribute to the allelic architecture of both carrier and recessive disease-causing mutations. Thus, a complete recessive carrier screening method or diagnostic test should detect CNV alleles. PMID:23685542

  3. 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

  4. Fryns Syndrome Associated with Recessive Mutations in PIGN in two Separate Families.

    PubMed

    McInerney-Leo, Aideen M; Harris, Jessica E; Gattas, Michael; Peach, Elizabeth E; Sinnott, Stephen; Dudding-Byth, Tracy; Rajagopalan, Sulekha; Barnett, Christopher P; Anderson, Lisa K; Wheeler, Lawrie; Brown, Matthew A; Leo, Paul J; Wicking, Carol; Duncan, Emma L

    2016-07-01

    Fryns syndrome is an autosomal recessive condition characterized by congenital diaphragmatic hernia (CDH), dysmorphic facial features, distal digital hypoplasia, and other associated malformations, and is the most common syndromic form of CDH. No gene has been associated with this condition. Whole-exome sequence data from two siblings and three unrelated individuals with Fryns syndrome were filtered for rare, good quality, coding mutations fitting a recessive inheritance model. Compound heterozygous mutations in PIGN were identified in the siblings, with appropriate parental segregation: a novel STOP mutation (c.1966C>T: p.Glu656X) and a rare (minor allele frequency <0.001) donor splice site mutation (c.1674+1G>C) causing skipping of exon 18 and utilization of a cryptic acceptor site in exon 19. A further novel homozygous STOP mutation in PIGN (c.694A>T: p.Lys232X) was detected in one unrelated case. All three variants affected highly conserved bases. The two remaining cases were negative for PIGN mutations. Mutations in PIGN have been reported in cases with multiple congenital anomalies, including one case with syndromic CDH. Fryns syndrome can be caused by recessive mutations in PIGN. Whether PIGN affects other syndromic and non-syndromic forms of CDH warrants investigation. PMID:27038415

  5. 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

  6. 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. PMID:23830518

  7. TMPRSS3 mutations in autosomal recessive nonsyndromic hearing loss.

    PubMed

    Battelino, Saba; Klancar, Gasper; Kovac, Jernej; Battelino, Tadej; Trebusak Podkrajsek, Katarina

    2016-05-01

    Nonsyndromic genetic deafness is highly heterogeneous in its clinical presentation, pattern of inheritance and underlying genetic causes. Mutations in TMPRSS3 gene encoding transmembrane serine protease account for <1 % of autosomal recessive nonsyndromic hearing loss (ARNSHL) in Caucasians. Targeted next generation sequencing in the index family with profound deaf parents and a son, and Sanger sequencing of selected TMPRSS3 gene regions in a cohort of thirty-five patients with suspected ARNSHL was adopted. A son and his mother in the index family were homozygous for TMPRSS3 c.208delC (p.His70Thrfs*19) variant. Father was digenic compound heterozygote for the same variant and common GJB2 c.35delG variant. Three additional patients from the ARNSHL cohort were homozygous for TMPRSS3 c.208delC. TMPRSS3 defects seem to be an important cause of ARNSHL in Slovenia resulting in uniform phenotype with profound congenital hearing loss, and satisfactory hearing and speech recognition outcome after cochlear implantation. Consequently, TMPRSS3 gene analysis should be included in the first tier of genetic investigations of ARNSHL along with GJB2 and GJB6 genes. PMID:26036852

  8. Negative regulation in the expression of a sugar-inducible gene in Arabidopsis thaliana. A recessive mutation causing enhanced expression of a gene for beta-amylase.

    PubMed Central

    Mita, S; Hirano, H; Nakamura, K

    1997-01-01

    Expression of a beta-amylase gene of Arabidopsis thaliana (AT beta-Amy) is regulated by sugars. We identified a mutant, hba1, in which the level of expression of AT beta-Amy in leaves of plants that had been grown in a medium with 2% sucrose was significantly higher than that in wild-type plants. Higher that wild-type levels of beta-amylase in hba1 plants depended on the presence of 1 to 2% sucrose or 1% glucose in the medium, whereas leaves of mutant plants grown with higher levels of sugars had beta-amylase activities similar to those in leaves of wild-type plants. The hba1 phenotype was recessive and did not affect levels of sugars and starch in leaves. It is proposed that expression of AT beta-Amy is regulated by a combination of both positive and negative factors, dependent on the level of sugars, and that HBA1 might function to maintain low-level expression of AT beta-Amy until the level of sugars reaches some high level. Results of crosses of hba1 plants with transgenic plants that harbored an AT beta-Amy:GUS transgene with 1587 bp of the 5'-upstream region suggested that HBA1 affects expressions of AT beta-Amy in trans. The hba1 plants also had growth defects and elevated levels of anthocyanin in their petioles. However, sugar-related changes in levels of several mRNAs other than beta-amylase mRNA were unaffected in hba1 plants, suggesting that only a subset of sugar-regulated genes is under the control HBA1. PMID:9193090

  9. 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. PMID:24170138

  10. Recessive TBC1D24 Mutations Are Frequent in Moroccan Non-Syndromic Hearing Loss Pedigrees

    PubMed Central

    Bakhchane, Amina; Charif, Majida; Salime, Sara; Boulouiz, Redouane; Nahili, Halima; Roky, Rachida

    2015-01-01

    Mutations in the TBC1D24 gene are responsible for four neurological presentations: infantile epileptic encephalopathy, infantile myoclonic epilepsy, DOORS (deafness, onychodystrophy, osteodystrophy, mental retardation and seizures) and NSHL (non-syndromic hearing loss). For the latter, two recessive (DFNB86) and one dominant (DFNA65) mutations have so far been identified in consanguineous Pakistani and European/Chinese families, respectively. Here we report the results of a genetic study performed on a large Moroccan cohort of deaf patients that identified three families with compound heterozygote mutations in TBC1D24. Four novel mutations were identified, among which, one c.641G>A (p.Arg214His) was present in the three families, and has a frequency of 2% in control Moroccan population with normal hearing, suggesting that it acts as an hypomorphic variant leading to restricted deafness when combined with another recessive severe mutation. Altogether, our results show that mutations in TBC1D24 gene are a frequent cause (>2%) of NSHL in Morocco, and that due to its possible compound heterozygote recessive transmission, this gene should be further considered and screened in other deaf cohorts. PMID:26371875

  11. 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.

  12. Autosomal recessive cystinuria caused by genome-wide paternal uniparental isodisomy in a patient with Beckwith-Wiedemann syndrome.

    PubMed

    Ohtsuka, Y; Higashimoto, K; Sasaki, K; Jozaki, K; Yoshinaga, H; Okamoto, N; Takama, Y; Kubota, A; Nakayama, M; Yatsuki, H; Nishioka, K; Joh, K; Mukai, T; Yoshiura, K-i; Soejima, H

    2015-09-01

    Approximately 20% of Beckwith-Wiedemann syndrome (BWS) cases are caused by mosaic paternal uniparental disomy of chromosome 11 (pUPD11). Although pUPD11 is usually limited to the short arm of chromosome 11, a small minority of BWS cases show genome-wide mosaic pUPD (GWpUPD). These patients show variable clinical features depending on mosaic ratio, imprinting status of other chromosomes, and paternally inherited recessive mutations. To date, there have been no reports of a mosaic GWpUPD patient with an autosomal recessive disease caused by a paternally inherited recessive mutation. Here, we describe a patient concurrently showing the clinical features of BWS and autosomal recessive cystinuria. Genetic analyses revealed that the patient has mosaic GWpUPD and an inherited paternal homozygous mutation in SLC7A9. This is the first report indicating that a paternally inherited recessive mutation can cause an autosomal recessive disease in cases of GWpUPD mosaicism. Investigation into recessive mutations and the dysregulation of imprinting domains is critical in understanding precise clinical conditions of patients with mosaic GWpUPD. PMID:25171146

  13. Integrin Alpha 8 Recessive Mutations Are Responsible for Bilateral Renal Agenesis in Humans

    PubMed Central

    Humbert, Camille; Silbermann, Flora; Morar, Bharti; Parisot, Mélanie; Zarhrate, Mohammed; Masson, Cécile; Tores, Frédéric; Blanchet, Patricia; Perez, Marie-José; Petrov, Yuliya; Khau Van Kien, Philippe; Roume, Joelle; Leroy, Brigitte; Gribouval, Olivier; Kalaydjieva, Luba; Heidet, Laurence; Salomon, Rémi; Antignac, Corinne; Benmerah, Alexandre; Saunier, Sophie; Jeanpierre, Cécile

    2014-01-01

    Renal hypodysplasia (RHD) is a heterogeneous condition encompassing a spectrum of kidney development defects including renal agenesis, hypoplasia, and (cystic) dysplasia. Heterozygous mutations of several genes have been identified as genetic causes of RHD with various severity. However, these genes and mutations are not associated with bilateral renal agenesis, except for RET mutations, which could be involved in a few cases. The pathophysiological mechanisms leading to total absence of kidney development thus remain largely elusive. By using a whole-exome sequencing approach in families with several fetuses with bilateral renal agenesis, we identified recessive mutations in the integrin α8-encoding gene ITGA8 in two families. Itga8 homozygous knockout in mice is known to result in absence of kidney development. We provide evidence of a damaging effect of the human ITGA8 mutations. These results demonstrate that mutations of ITGA8 are a genetic cause of bilateral renal agenesis and that, at least in some cases, bilateral renal agenesis is an autosomal-recessive disease. PMID:24439109

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

    PubMed Central

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

    2015-01-01

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

  15. HACE1 deficiency causes an autosomal recessive neurodevelopmental syndrome

    PubMed Central

    Hollstein, Ronja; Parry, David A; Nalbach, Lisa; Logan, Clare V; Strom, Tim M; Hartill, Verity L; Carr, Ian M; Korenke, Georg C; Uppal, Sandeep; Ahmed, Mushtaq; Wieland, Thomas; Markham, Alexander F; Bennett, Christopher P; Gillessen-Kaesbach, Gabriele; Sheridan, Eamonn G; Kaiser, Frank J; Bonthron, David T

    2015-01-01

    Background The genetic aetiology of neurodevelopmental defects is extremely diverse, and the lack of distinctive phenotypic features means that genetic criteria are often required for accurate diagnostic classification. We aimed to identify the causative genetic lesions in two families in which eight affected individuals displayed variable learning disability, spasticity and abnormal gait. Methods Autosomal recessive inheritance was suggested by consanguinity in one family and by sibling recurrences with normal parents in the second. Autozygosity mapping and exome sequencing, respectively, were used to identify the causative gene. Results In both families, biallelic loss-of-function mutations in HACE1 were identified. HACE1 is an E3 ubiquitin ligase that regulates the activity of cellular GTPases, including Rac1 and members of the Rab family. In the consanguineous family, a homozygous mutation p.R219* predicted a truncated protein entirely lacking its catalytic domain. In the other family, compound heterozygosity for nonsense mutation p.R748* and a 20-nt insertion interrupting the catalytic homologous to the E6-AP carboxyl terminus (HECT) domain was present; western blot analysis of patient cells revealed an absence of detectable HACE1 protein. Conclusion HACE1 mutations underlie a new autosomal recessive neurodevelopmental disorder. Previous studies have implicated HACE1 as a tumour suppressor gene; however, since cancer predisposition was not observed either in homozygous or heterozygous mutation carriers, this concept may require re-evaluation. PMID:26424145

  16. Identification of 45 novel mutations in the nebulin gene associated with autosomal recessive nemaline myopathy.

    PubMed

    Lehtokari, Vilma-Lotta; Pelin, Katarina; Sandbacka, Maria; Ranta, Salla; Donner, Kati; Muntoni, Francesco; Sewry, Caroline; Angelini, Corrado; Bushby, Kate; Van den Bergh, Peter; Iannaccone, Susan; Laing, Nigel G; Wallgren-Pettersson, Carina

    2006-09-01

    Nemaline myopathy (NM) is a clinically and genetically heterogeneous disorder of skeletal muscle caused by mutations in at least five different genes encoding thin filament proteins of the striated muscle sarcomere. We have previously described 18 different mutations in the last 42 exons of the nebulin gene (NEB) in 18 families with NM. Here we report 45 novel NEB mutations detected by denaturing high-performance liquid chromatography (dHPLC) and sequence analysis of all 183 NEB exons in NM patients from 44 families. Altogether we have identified, including the deletion of exon 55 identified in the Ashkenazi Jewish population, 64 different mutations in NEB segregating with autosomal recessive NM in 55 families. The majority (55%) of the mutations in NEB are frameshift or nonsense mutations predicted to cause premature truncation of nebulin. Point mutations (25%) or deletions (3%) affecting conserved splice signals are predicted in the majority of cases to cause in-frame exon skipping, possibly leading to impaired nebulin-tropomyosin interaction along the thin filament. Patients in 18 families had one of nine missense mutations (14%) affecting conserved amino acids at or in the vicinity of actin or tropomyosin binding sites. In addition, we found the exon 55 deletion in four families. The majority of the patients (in 49/55 families) were shown to be compound heterozygous for two different mutations. The mutations were found in both constitutively and alternatively expressed exons throughout the NEB gene, and there were no obvious mutational hotspots. Patients with more severe clinical pictures tended to have mutations predicted to be more disruptive than patients with milder forms. PMID:16917880

  17. 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

  18. 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

  19. TRAPPC9-related autosomal recessive intellectual disability: report of a new mutation and clinical phenotype.

    PubMed

    Marangi, Giuseppe; Leuzzi, Vincenzo; Manti, Filippo; Lattante, Serena; Orteschi, Daniela; Pecile, Vanna; Neri, Giovanni; Zollino, Marcella

    2013-02-01

    Intellectual disability (ID) with autosomal recessive (AR) inheritance is believed to be common; however, very little is known about causative genes and genotype-phenotype correlations. The broad genetic heterogeneity of AR-ID, and its usually nonsyndromic nature make it difficult to pool multiple pedigrees with the same underlying genetic defect to achieve consistent nosology. Nearly all autosomal genes responsible for recessive cognitive disorders have been identified in large consanguineous families from the Middle East, and nonsense mutations in TRAPPC9 have been reported in a total of 5. Although several recurrent phenotypic abnormalities are described in some of these patients, the associated phenotype is usually referred to as nonsyndromic. By means of single-nucleotide polymorphism-array first and then by exome sequencing, we identified a new pathogenic mutation in TRAPPC9 in two Italian sisters born to healthy and apparently nonconsanguineous parents. It consists of a homozygous splice site mutation causing exon skipping with frameshift and premature termination, as confirmed by mRNA sequencing. By detailed phenotypic analysis of our patients, and by critical literature review, we found that homozygous TRAPPC9 loss-of-function mutations cause a distinctive phenotype, characterized by peculiar facial appearance, obesity, hypotonia (all signs resembling a Prader-Willi-like phenotype), moderate-to-severe ID, and consistent brain abnormalities. PMID:22549410

  20. LRIG2 Mutations Cause Urofacial Syndrome

    PubMed Central

    Stuart, Helen M.; Roberts, Neil A.; Burgu, Berk; Daly, Sarah B.; Urquhart, Jill E.; Bhaskar, Sanjeev; Dickerson, Jonathan E.; Mermerkaya, Murat; Silay, Mesrur Selcuk; Lewis, Malcolm A.; Olondriz, M. Beatriz Orive; Gener, Blanca; Beetz, Christian; Varga, Rita E.; Gülpınar, Ömer; Süer, Evren; Soygür, Tarkan; Özçakar, Zeynep B.; Yalçınkaya, Fatoş; Kavaz, Aslı; Bulum, Burcu; Gücük, Adnan; Yue, Wyatt W.; Erdogan, Firat; Berry, Andrew; Hanley, Neil A.; McKenzie, Edward A.; Hilton, Emma N.; Woolf, Adrian S.; Newman, William G.

    2013-01-01

    Urofacial syndrome (UFS) (or Ochoa syndrome) is an autosomal-recessive disease characterized by congenital urinary bladder dysfunction, associated with a significant risk of kidney failure, and an abnormal facial expression upon smiling, laughing, and crying. We report that a subset of UFS-affected individuals have biallelic mutations in LRIG2, encoding leucine-rich repeats and immunoglobulin-like domains 2, a protein implicated in neural cell signaling and tumorigenesis. Importantly, we have demonstrated that rare variants in LRIG2 might be relevant to nonsyndromic bladder disease. We have previously shown that UFS is also caused by mutations in HPSE2, encoding heparanase-2. LRIG2 and heparanase-2 were immunodetected in nerve fascicles growing between muscle bundles within the human fetal bladder, directly implicating both molecules in neural development in the lower urinary tract. PMID:23313374

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

    PubMed Central

    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

    2016-01-01

    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. PMID:26806561

  2. 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

  3. TRPM1 Is Mutated in Patients with Autosomal-Recessive Complete Congenital Stationary Night Blindness

    PubMed Central

    Audo, Isabelle; Kohl, Susanne; Leroy, Bart P.; Munier, Francis L.; Guillonneau, Xavier; Mohand-Saïd, Saddek; Bujakowska, Kinga; Nandrot, Emeline F.; Lorenz, Birgit; Preising, Markus; Kellner, Ulrich; Renner, Agnes B.; Bernd, Antje; Antonio, Aline; Moskova-Doumanova, Veselina; Lancelot, Marie-Elise; Poloschek, Charlotte M.; Drumare, Isabelle; Defoort-Dhellemmes, Sabine; Wissinger, Bernd; Léveillard, Thierry; Hamel, Christian P.; Schorderet, Daniel F.; De Baere, Elfride; Berger, Wolfgang; Jacobson, Samuel G.; Zrenner, Eberhart; Sahel, José-Alain; Bhattacharya, Shomi S.; Zeitz, Christina

    2009-01-01

    Night vision requires signaling from rod photoreceptors to adjacent bipolar cells in the retina. Mutations in the genes NYX and GRM6, expressed in ON bipolar cells, lead to a disruption of the ON bipolar cell response. This dysfunction is present in patients with complete X-linked and autosomal-recessive congenital stationary night blindness (CSNB) and can be assessed by standard full-field electroretinography (ERG), showing severely reduced rod b-wave amplitude and slightly altered cone responses. Although many cases of complete CSNB (cCSNB) are caused by mutations in NYX and GRM6, in ∼60% of the patients the gene defect remains unknown. Animal models of human diseases are a good source for candidate genes, and we noted that a cCSNB phenotype present in homozygous Appaloosa horses is associated with downregulation of TRPM1. TRPM1, belonging to the family of transient receptor potential channels, is expressed in ON bipolar cells and therefore qualifies as an excellent candidate. Indeed, mutation analysis of 38 patients with CSNB identified ten unrelated cCSNB patients with 14 different mutations in this gene. The mutation spectrum comprises missense, splice-site, deletion, and nonsense mutations. We propose that the cCSNB phenotype in these patients is due to the absence of functional TRPM1 in retinal ON bipolar cells. PMID:19896113

  4. 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

  5. Novel ITGB6 mutation in autosomal recessive amelogenesis imperfecta

    PubMed Central

    Seymen, F; Lee, K-E; Koruyucu, M; Gencay, K; Bayram, M; Tuna, EB; Lee, ZH; Kim, J-W

    2015-01-01

    Objective Hereditary defects in tooth enamel formation, amelogenesis imperfecta (AI), can be non-syndromic or syndromic phenotype. Integrins are signaling proteins that mediate cell–cell and cell–extracellular matrix communication, and their involvement in tooth development is well known. The purposes of this study were to identify genetic cause of an AI family and molecular pathogenesis underlying defective enamel formation. Materials and Methods We recruited a Turkish family with isolated AI and performed mutational analyses to clarify the underlying molecular genetic etiology. Results Autozygosity mapping and exome sequencing identified a novel homozygous ITGB6 transversion mutation in exon 4 (c.517G>C, p.Gly173Arg). The glycine at this position in the middle of the βI-domain is conserved among a wide range of vertebrate orthologs and human paralogs. Clinically, the enamel was generally thin and pitted with pigmentation. Thicker enamel was noted at the cervical area of the molars. Conclusions In this study, we identified a novel homozygous ITGB6 mutation causing isolated AI, and this advances the understanding of normal and pathologic enamel development. PMID:25431241

  6. 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. PMID:20842367

  7. 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

  8. 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

  9. 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

  10. 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. PMID:23236289

  11. 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

  12. Autosomal recessive primary microcephaly (MCPH): clinical manifestations, genetic heterogeneity and mutation continuum

    PubMed Central

    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

  13. 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

  14. 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

  15. Exome sequencing reveals a thrombopoietin ligand mutation in a Micronesian family with autosomal recessive aplastic anemia

    PubMed Central

    Rafi, Syed K.; Olm-Shipman, Adam J.; Wilson, Nathan R.; Abhyankar, Sunil; Ganter, Brigitte; Furness, L. Mike; Fang, Jianwen; Calado, Rodrigo T.

    2013-01-01

    We recently identified 2 siblings afflicted with idiopathic, autosomal recessive aplastic anemia. Whole-exome sequencing identified a novel homozygous missense mutation in thrombopoietin (THPO, c.112C>T) in both affected siblings. This mutation encodes an arginine to cysteine substitution at residue 38 or residue 17 excluding the 21-amino acid signal peptide of THPO receptor binding domain (RBD). THPO has 4 conserved cysteines in its RBD that form 2 disulfide bonds. Our in silico modeling predicts that introduction of a fifth cysteine may disrupt normal disulfide bonding to cause poor receptor binding. In functional assays, the mutant-THPO–containing media shows two- to threefold reduced ability to sustain UT7-TPO cells, which require THPO for proliferation. Both parents and a sibling with heterozygous R17C change have reduced platelet counts, whereas a sibling with wild-type sequence has normal platelet count. Thus, the R17C partial loss-of-function allele results in aplastic anemia in the homozygous state and mild thrombocytopenia in the heterozygous state in our family. Together with the recent identification of THPO receptor (MPL) mutations and the effects of THPO agonists in aplastic anemia, our results have clinical implications in the diagnosis and treatment of patients with aplastic anemia and highlight a role for the THPO-MPL pathway in hematopoiesis in vivo. PMID:24085763

  16. Recessive REEP1 mutation is associated with congenital axonal neuropathy and diaphragmatic palsy

    PubMed Central

    Schottmann, Gudrun; Seelow, Dominik; Seifert, Franziska; Morales-Gonzalez, Susanne; Gill, Esther; von Au, Katja; von Moers, Arpad; Stenzel, Werner

    2015-01-01

    Objective: To identify the underlying genetic cause of a congenital neuropathy in a 5-year-old boy as part of a cohort of 32 patients from 23 families with genetically unresolved neuropathies. Methods: We used autozygosity mapping coupled with next-generation sequencing to investigate a consanguineous family from Lebanon with 1 affected and 2 healthy children. Variants were investigated for segregation in the family by Sanger sequencing. A splice site mutation was further evaluated on the messenger RNA level by quantitative reverse transcription PCR. Subsequently, a larger cohort was specifically screened for receptor expression-enhancing protein 1 (REEP1) gene mutations. Results: We detected a homozygous splice donor mutation in REEP1 (c.303+1-7GTAATAT>AC, p.F62Kfs23*; NM_022912) that cosegregated with the phenotype in the family, leading to complete skipping of exon 4 and a premature stop codon. The phenotype of the patient is similar to spinal muscular atrophy with respiratory distress type 1 (SMARD1) with additional distal arthrogryposis and involvement of the upper motor neuron manifested by pronounced hyperreflexia. Conclusion: To date, only dominant REEP1 mutations have been reported to be associated with a slowly progressive hereditary spastic paraplegia. The findings from our patient expand the phenotypical spectrum and the mode of inheritance of REEP1-associated disorders. Recessive mutations in REEP1 should be considered in the molecular genetic workup of patients with a neuromuscular disorder resembling SMARD1, especially if additional signs of upper motor neuron involvement and distal arthrogryposis are present. PMID:27066569

  17. 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.

  18. Novel mutation in TSPAN12 leads to autosomal recessive inheritance of congenital vitreoretinal disease with intra-familial phenotypic variability.

    PubMed

    Gal, Moran; Levanon, Erez Y; Hujeirat, Yasir; Khayat, Morad; Pe'er, Jacob; Shalev, Stavit

    2014-12-01

    Developmental malformations of the vitreoretinal vasculature are a heterogeneous group of conditions with various modes of inheritance, and include familial exudative vitreoretinopathy (FEVR), persistent fetal vasculature (PFV), and Norrie disease. We investigated a large consanguineous kindred with multiple affected individuals exhibiting variable phenotypes of abnormal vitreoretinal vasculature, consistent with the three above-mentioned conditions and compatible with autosomal recessive inheritance. Exome sequencing identified a novel c.542G > T (p.C181F) apparently mutation in the TSPAN12 gene that segregated with the ocular disease in the family. The TSPAN12 gene was previously reported to cause dominant and recessive FEVR, but has not yet been associated with other vitreoretinal manifestations. The intra-familial clinical variability caused by a single mutation in the TSPAN12 gene underscores the complicated phenotype-genotype correlation of mutations in this gene, and suggests that there are additional genetic and environmental factors involved in the complex process of ocular vascularization during embryonic development. Our study supports considering PFV, FEVR, and Norrie disease a spectrum of disorders, with clinical and genetic overlap, caused by mutations in distinct genes acting in the Norrin/β-catenin signaling pathway. PMID:25250762

  19. 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

  20. 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

  1. Large Deletions and Point Mutations Involving DOCK8 in the Autosomal Recessive Form of the Hyper-IgE Syndrome

    PubMed Central

    Engelhardt, Karin R.; McGhee, Sean; Winkler, Sabine; Sassi, Atfa; Woellner, Cristina; Lopez-Herrera, Gabriela; Chen, Andrew; Kim, Hong Sook; Lloret, Maria Garcia; Schulze, Ilka; Ehl, Stephan; Thiel, Jens; Pfeifer, Dietmar; Veelken, Hendrik; Niehues, Tim; Siepermann, Kathrin; Weinspach, Sebastian; Reisli, Ismail; Keles, Sevgi; Genel, Ferah; Kütükçüler, Necil; Camcioğlu, Yildiz; Somer, Ayper; Aydiner, Elif Karakoc; Barlan, Isil; Gennery, Andrew; Metin, Ayse; Degerliyurt, Aydan; Pietrogrande, Maria C.; Yeganeh, Mehdi; Baz, Zeina; Al-Tamemi, Salem; Klein, Christoph; Puck, Jennifer M.; Holland, Steven M.; McCabe, Edward R. B.; Grimbacher, Bodo; Chatila, Talal

    2010-01-01

    Background The genetic etiologies of the hyper-IgE syndromes are diverse. Approximately 60-70% of patients with hyper-IgE syndrome have dominant mutations in STAT3, and a single patient was reported to have a homozygous TYK2 mutation. In the remaining hyper-IgE syndrome patients, the genetic etiology has not yet been identified. Methods We performed genome-wide single nucleotide polymorphism analysis for nine subjects with autosomal recessive hyper-IgE syndrome to locate copy number variations and homozygous haplotypes. Homozygosity mapping was performed with twelve subjects from seven additional families. The candidate gene was analyzed by genomic and cDNA sequencing to identify causative alleles in a total of 27 patients with autosomal recessive hyper-IgE syndrome. Findings Subtelomeric microdeletions were identified in six subjects at the terminus of chromosome 9p. In all patients the deleted interval involved DOCK8, encoding a protein implicated in the regulation of the actin cytoskeleton. Sequencing of subjects without large deletions revealed 16 patients from nine unrelated families with distinct homozygous mutations in DOCK8 causing premature termination, frameshift, splice site disruption, single exon- and micro-deletions. DOCK8 deficiency was associated with impaired activation of CD4+ and CD8+ T cells. Interpretation Autosomal recessive mutations in DOCK8 are responsible for many, though not all, cases of autosomal recessive hyper-IgE syndrome. DOCK8 disruption is associated with a phenotype of severe cellular immunodeficiency characterized by susceptibility to viral infections, atopic eczema, defective T cell activation and TH17 cell differentiation; and impaired eosinophil homeostasis and dysregulation of IgE. PMID:20004785

  2. 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

  3. 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

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

    PubMed

    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

    2016-07-01

    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

  5. 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

  6. 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

  7. 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

  8. 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

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

    PubMed Central

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

    2008-01-01

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

  10. 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

  11. 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

  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. PMID:25552650

  13. 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

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

    SciTech Connect

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

    1994-09-01

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

  15. 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

  16. Cysteine mutations cause defective tyrosine phosphorylation in MEGF10 myopathy

    PubMed Central

    Mitsuhashi, Satomi; Mitsuhashi, Hiroaki; Alexander, Matthew S; Sugimoto, Hiroyuki; Kang, Peter B

    2013-01-01

    Recessive mutations in MEGF10 are known to cause a congenital myopathy in humans. Two mutations in the extracellular EGF-like domains of MEGF10, C326R and C774R, were associated with decreased tyrosine phosphorylation of MEGF10 in vitro. Y1030 was identified to be the major tyrosine phosphorylation site in MEGF10 and is phosphorylated at least in part by c-Src. Overexpression of wild-type MEGF10 enhanced C2C12 myoblast proliferation, while overexpression of Y1030F mutated MEGF10 did not. We conclude that MEGF10-mediated signaling via tyrosine phosphorylation helps to regulate myoblast proliferation. Defects in this signaling pathway may contribute to the disease mechanism of MEGF10 myopathy. PMID:23954233

  17. 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

  18. 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

  19. Thymidine phosphorylase mutations cause instability of mitochondrial DNA.

    PubMed

    Hirano, Michio; Lagier-Tourenne, Clotilde; Valentino, Maria L; Martí, Ramon; Nishigaki, Yutaka

    2005-07-18

    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an autosomal recessive disorder characterized by ptosis and progressive external ophthalmoplegia, peripheral neuropathy, severe gastrointestinal dysmotility, cachexia and leukoencephalopathy. Muscle biopsies of MNGIE patients have revealed morphologically abnormal mitochondria and defects of respiratory chain enzymes. In addition, patients harbor depletion, multiple deletions, and point mutations of mitochondrial DNA (mtDNA). This disorder is caused by loss-of-function mutations in the gene encoding thymidine phosphorylase (TP) a cytosolic enzyme. In MNGIE patients, TP activity is very low or absent resulting in dramatically elevated levels of plasma thymidine and deoxyuridine. We have hypothesized that the increased levels of thymidine and deoxyuridine cause mitochondrial nucleotide pool imbalances that, in turn, generate mtDNA alterations. PMID:15975738

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

    PubMed

    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

  1. Selection and mutation in X-linked recessive diseases epidemiological model.

    PubMed

    Verrilli, Francesca; Kebriaei, Hamed; Glielmo, Luigi; Corless, Martin; Del Vecchio, Carmen

    2015-08-01

    To describe the epidemiology of X-linked recessive diseases we developed a discrete time, structured, non linear mathematical model. The model allows for de novo mutations (i.e. affected sibling born to unaffected parents) and selection (i.e., distinct fitness rates depending on individual's health conditions). Applying Lyapunov direct method we found the domain of attraction of model's equilibrium point and studied the convergence properties of the degenerate equilibrium where only affected individuals survive. PMID:26737169

  2. 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.

  3. 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

  4. Mutations in SLC26A1 Cause Nephrolithiasis.

    PubMed

    Gee, Heon Yung; Jun, Ikhyun; Braun, Daniela A; Lawson, Jennifer A; Halbritter, Jan; Shril, Shirlee; Nelson, Caleb P; Tan, Weizhen; Stein, Deborah; Wassner, Ari J; Ferguson, Michael A; Gucev, Zoran; Sayer, John A; Milosevic, Danko; Baum, Michelle; Tasic, Velibor; Lee, Min Goo; Hildebrandt, Friedhelm

    2016-06-01

    Nephrolithiasis, a condition in which urinary supersaturation leads to stone formation in the urinary system, affects about 5%-10% of individuals worldwide at some point in their lifetime and results in significant medical costs and morbidity. To date, mutations in more than 30 genes have been described as being associated with nephrolithiasis, and these mutations explain about 15% of kidney stone cases, suggesting that additional nephrolithiasis-associated genes remain to be discovered. To identify additional genes whose mutations are linked to nephrolithiasis, we performed targeted next-generation sequencing of 18 hypothesized candidate genes in 348 unrelated individuals with kidney stones. We detected biallelic mutations in SLC26A1 (solute carrier family 26 member 1) in two unrelated individuals with calcium oxalate kidney stones. We show by immunofluorescence, immunoblotting, and glycosylation analysis that the variant protein mimicking p.Thr185Met has defects in protein folding or trafficking. In addition, by measuring anion exchange activity of SLC26A1, we demonstrate that all the identified mutations in SLC26A1 result in decreased transporter activity. Our data identify SLC26A1 mutations as causing a recessive Mendelian form of nephrolithiasis. PMID:27210743

  5. 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

  6. Mutations in SERPINF1 Cause Osteogenesis Imperfecta Type VI

    PubMed Central

    Homan, Erica P; Rauch, Frank; Grafe, Ingo; Lietman, Caressa; Doll, Jennifer A; Dawson, Brian; Bertin, Terry; Napierala, Dobrawa; Morello, Roy; Gibbs, Richard; White, Lisa; Miki, Rika; Cohn, Daniel H; Crawford, Susan; Travers, Rose; Glorieux, Francis H; Lee, Brendan

    2011-01-01

    Abstract Osteogenesis imperfecta (OI) is a spectrum of genetic disorders characterized by bone fragility. It is caused by dominant mutations affecting the synthesis and/or structure of type I procollagen or by recessively inherited mutations in genes responsible for the posttranslational processing/trafficking of type I procollagen. Recessive OI type VI is unique among OI types in that it is characterized by an increased amount of unmineralized osteoid, thereby suggesting a distinct disease mechanism. In a large consanguineous family with OI type VI, we performed homozygosity mapping and next-generation sequencing of the candidate gene region to isolate and identify the causative gene. We describe loss of function mutations in serpin peptidase inhibitor, clade F, member 1 (SERPINF 1) in two affected members of this family and in an additional unrelated patient with OI type VI. SERPINF1 encodes pigment epithelium-derived factor. Hence, loss of pigment epithelium-derived factor function constitutes a novel mechanism for OI and shows its involvement in bone mineralization. © 2011 American Society for Bone and Mineral Research PMID:21826736

  7. 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

  8. 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

  9. 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

  10. Novel compound heterozygous mutation in the CNGA1 gene underlie autosomal recessive retinitis pigmentosa in a Chinese family

    PubMed Central

    Jin, Xin; Qu, Ling-Hui; Hou, Bao-Ke; Xu, Hai-Wei; Meng, Xiao-Hong; Pang, Chi-Pui; Yin, Zheng-Qin

    2016-01-01

    Retinitis pigmentosa (RP) describes a group of inherited retinopathies that are characterized by the progressive degeneration of photoreceptor neurons, which causes night blindness, a reduction in the peripheral visual field and decreased visual acuity. More than 50 RP-related genes have been identified. In the present study, we analysed a Chinese family with autosomal recessive RP. We identified a compound heterozygous mutation, c.265delC and c.1537G>A, in CNGA1 using targeted next-generation sequencing (NGS) of RP-causing genes. The mutations were validated in the family members by Sanger sequencing. The mutations co-segregated with the RP phenotype and were absent from ethnically-matched control chromosomes. The mutant (mut) CNGA1 p.(G513R) protein caused by the mis-sense novel mutation c.1537G>A was expressed in vitro. The mut CNGA1 p.(G513R) protein was largely retained inside the cell rather than being targeted to the plasma membrane, suggesting the absence of cGMP-gated cation channels in the plasma membrane would be deleterious to rod photoreceptors, leading lead to RP. PMID:26802146

  11. Identification of novel type VII collagen gene mutations resulting in severe recessive dystrophic epidermolysis bullosa.

    PubMed

    Massé, M; Cserhalmi-Friedman, P B; Falanga, V; Celebi, J T; Martinez-Mir, A; Christiano, A M

    2005-05-01

    In this work, we studied the proband in a small nuclear family of Chinese and Dutch/German descent and identified two novel mutations in the type VII collagen gene leading to recessive dystrophic epidermolysis bullosa, Hallopeau-Siemens variant (HS-RDEB). The maternal mutation is a single base pair deletion of a cytosine nucleotide in exon 26, designated 3472delC, resulting in a frameshift and a premature termination codon (PTC) within the same exon, 7 bp downstream of the site of the mutation. The paternal mutation is a G-->A transition located at the 5' donor splice site within intron 51, designated IVS51 + 1G-->A. This mutation leads to the activation of a cryptic splice site, 32 bp downstream of the mutation site and to subsequent aberrant out-of-frame splicing, resulting in two alternative mRNA transcripts and a downstream PTC. To our knowledge, these two mutations have not been previously reported. These findings extend the body of evidence for compound heterozygous mutations leading to HS-RDEB and provide the basis for prenatal diagnosis in this family. PMID:15807692

  12. 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. PMID:22246887

  13. 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

  14. 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

  15. [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

  16. 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

  17. 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

  18. 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 inPOMGNT1, 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

  19. 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

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

    PubMed

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

    2007-06-01

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

  1. 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.

  2. Functional characterization of ClC-1 mutations from patients affected by recessive myotonia congenita presenting with different clinical phenotypes.

    PubMed

    Desaphy, Jean-François; Gramegna, Gianluca; Altamura, Concetta; Dinardo, Maria Maddalena; Imbrici, Paola; George, Alfred L; Modoni, Anna; Lomonaco, Mauro; Conte Camerino, Diana

    2013-10-01

    Myotonia congenita (MC) is caused by loss-of-function mutations of the muscle ClC-1 chloride channel. Clinical manifestations include the variable association of myotonia and transitory weakness. We recently described a cohort of recessive MC patients showing, at a low rate repetitive nerves stimulation protocol, different values of compound muscle action potential (CMAP) transitory depression, which is considered the neurophysiologic counterpart of transitory weakness. From among this cohort, we studied the chloride currents generated by G190S (associated with pronounced transitory depression), F167L (little or no transitory depression), and A531V (variable transitory depression) hClC-1 mutants in transfected HEK293 cells using patch-clamp. While F167L had no effect on chloride currents, G190S dramatically shifts the voltage dependence of channel activation and A531V reduces channel expression. Such variability in molecular mechanisms observed in the hClC-1 mutants may help to explain the different clinical and neurophysiologic manifestations of each ClCN1 mutation. In addition we examined five different mutations found in compound heterozygosis with F167L, including the novel P558S, and we identified additional molecular defects. Finally, the G190S mutation appeared to impair acetazolamide effects on chloride currents in vitro. PMID:23933576

  3. Functional characterization of ClC-1 mutations from patients affected by recessive myotonia congenita presenting with different clinical phenotypes☆

    PubMed Central

    Desaphy, Jean-François; Gramegna, Gianluca; Altamura, Concetta; Dinardo, Maria Maddalena; Imbrici, Paola; George, Alfred L.; Modoni, Anna; LoMonaco, Mauro; Conte Camerino, Diana

    2013-01-01

    Myotonia congenita (MC) is caused by loss-of-function mutations of the muscle ClC-1 chloride channel. Clinical manifestations include the variable association of myotonia and transitory weakness. We recently described a cohort of recessive MC patients showing, at a low rate repetitive nerves stimulation protocol, different values of compound muscle action potential (CMAP) transitory depression, which is considered the neurophysiologic counterpart of transitory weakness. From among this cohort, we studied the chloride currents generated by G190S (associated with pronounced transitory depression), F167L (little or no transitory depression), and A531V (variable transitory depression) hClC-1 mutants in transfected HEK293 cells using patch-clamp. While F167L had no effect on chloride currents, G190S dramatically shifts the voltage dependence of channel activation and A531V reduces channel expression. Such variability in molecular mechanisms observed in the hClC-1 mutants may help to explain the different clinical and neurophysiologic manifestations of each ClCN1 mutation. In addition we examined five different mutations found in compound heterozygosis with F167L, including the novel P558S, and we identified additional molecular defects. Finally, the G190S mutation appeared to impair acetazolamide effects on chloride currents in vitro. PMID:23933576

  4. The tumour suppressor gene WWOX is mutated in autosomal recessive cerebellar ataxia with epilepsy and mental retardation

    PubMed Central

    Mallaret, Martial; Synofzik, Matthis; Lee, Jaeho; Sagum, Cari A.; Mahajnah, Muhammad; Sharkia, Rajech; Drouot, Nathalie; Renaud, Mathilde; Klein, Fabrice A. C.; Anheim, Mathieu; Tranchant, Christine; Mignot, Cyril; Mandel, Jean-Louis; Bedford, Mark; Bauer, Peter; Salih, Mustafa A.; Schüle, Rebecca; Schöls, Ludger; Aldaz, C. Marcelo

    2014-01-01

    We previously localized a new form of recessive ataxia with generalized tonic-clonic epilepsy and mental retardation to a 19 Mb interval in 16q21-q23 by homozygosity mapping of a large consanguineous Saudi Arabian family. We now report the identification by whole exome sequencing of the missense mutation changing proline 47 into threonine in the first WW domain of the WW domain containing oxidoreductase gene, WWOX, located in the linkage interval. Proline 47 is a highly conserved residue that is part of the WW motif consensus sequence and is part of the hydrophobic core that stabilizes the WW fold. We demonstrate that proline 47 is a key amino acid essential for maintaining the WWOX protein fully functional, with its mutation into a threonine resulting in a loss of peptide interaction for the first WW domain. We also identified another highly conserved homozygous WWOX mutation changing glycine 372 to arginine in a second consanguineous family. The phenotype closely resembled the index family, presenting with generalized tonic-clonic epilepsy, mental retardation and ataxia, but also included prominent upper motor neuron disease. Moreover, we observed that the short-lived Wwox knock-out mouse display spontaneous and audiogenic seizures, a phenotype previously observed in the spontaneous Wwox mutant rat presenting with ataxia and epilepsy, indicating that homozygous WWOX mutations in different species causes cerebellar ataxia associated with epilepsy. PMID:24369382

  5. 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

  6. Novel and recurrent AID mutations underlie prevalent autosomal recessive form of HIGM in consanguineous patients.

    PubMed

    Ouadani, Hanen; Ben-Mustapha, Imen; Ben-ali, Meriem; Ben-khemis, Leila; Larguèche, Beya; Boussoffara, Raoudha; Maalej, Sonia; Fetni, Ilhem; Hassayoun, Saida; Mahfoudh, Abdelmajid; Mellouli, Fethi; Yalaoui, Sadok; Masmoudi, Hatem; Bejaoui, Mohamed; Barbouche, Mohamed-Ridha

    2016-01-01

    Immunoglobulin class switch recombination deficiencies (Ig-CSR-D) are characterized by normal or elevated serum IgM level and absence of IgG, IgA, and IgE. Most reported cases are due to X-linked CD40L deficiency. Activation-induced cytidine deaminase deficiency is the most frequent autosomal recessive form, whereas CD40 deficiency is more rare. Herein, we present the first North African study on hyper IgM (HIGM) syndrome including 16 Tunisian patients. Phenotypic and genetic studies allowed us to determine their molecular basis. Three CD40LG mutations have been identified including two novels (c.348_351dup and c.782_*2del) and one already reported mutation (g.6182G>A). No mutation has been found in another patient despite the lack of CD40L expression. Interestingly, three AICDA mutations have been identified in 11 patients. Two mutations were novel (c.91T>C and c.389A>C found in one and five patients respectively), and one previously reported splicing mutation (c.156+1T>G) was found in five patients. Only one CD40-deficient patient, bearing a novel mutation (c.109T>G), has been identified. Thus, unlike previous reports, AID deficiency is the most frequent underlying molecular basis (68%) of Ig-CSR-D in Tunisian patients. This finding and the presence of specific recurrent mutations are probably due to the critical role played by inbreeding in North African populations. PMID:26545377

  7. 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.

  8. Inherited cardiomyopathies caused by troponin mutations

    PubMed Central

    Lu, Qun-Wei; Wu, Xiao-Yan; Morimoto, Sachio

    2013-01-01

    Genetic investigations of cardiomyopathy in the recent two decades have revealed a large number of mutations in the genes encoding sarcomeric proteins as a cause of inherited hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), or restrictive cardiomyopathy (RCM). Most functional analyses of the effects of mutations on cardiac muscle contraction have revealed significant changes in the Ca2+-regulatory mechanism, in which cardiac troponin (cTn) plays important structural and functional roles as a key regulatory protein. Over a hundred mutations have been identified in all three subunits of cTn, i.e., cardiac troponins T, I, and C. Recent studies on cTn mutations have provided plenty of evidence that HCM- and RCM-linked mutations increase cardiac myofilament Ca2+ sensitivity, while DCM-linked mutations decrease it. This review focuses on the functional consequences of mutations found in cTn in terms of cardiac myofilament Ca2+ sensitivity, ATPase activity, force generation, and cardiac troponin I phosphorylation, to understand potential molecular and cellular pathogenic mechanisms of the three types of inherited cardiomyopathy. PMID:23610579

  9. 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.

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

    PubMed Central

    Brune, W.; Weber, R. G.; Saul, B.; von Knebel Doeberitz, M.; Grond-Ginsbach, C.; Kellerman, K.; Meinck, H. M.; Becker, C. M.

    1996-01-01

    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(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 spd-ot), the loss of the GlyR alpha 1 subunit is effectively compensated in man. Images Figure 2 Figure 3 Figure 4 Figure 5 PMID:8651283

  11. Dominant Maternal-Effect Mutations Causing Embryonic Lethality in Caenorhabditis Elegans

    PubMed Central

    Mains, P. E.; Sulston, I. A.; Wood, W. B.

    1990-01-01

    We undertook screens for dominant, temperature-sensitive, maternal-effect embryonic-lethal mutations of Caenorhabditis elegans as a way to identify certain classes of genes with early embryonic functions, in particular those that are members of multigene families and those that are required in two copies for normal development. The screens have identified eight mutations, representing six loci. Mutations at three of the loci result in only maternal effects on embryonic viability. Mutations at the remaining three loci cause additional nonmaternal (zygotic) effects, including recessive lethality or sterility and dominant male mating defects. Mutations at five of the loci cause visible pregastrulation defects. Three mutations appear to be allelic with a recessive mutation of let-354. Gene dosage experiments indicate that one mutation may be a loss-of-function allele at a haploin sufficient locus. The other mutations appear to result in gain-of-function ``poison'' gene products. Most of these become less deleterious as the relative dosage of the corresponding wild-type allele is increased; we show that relative self-progeny viabilities for the relevant hermaphrodite genotypes are generally M/+/+ > M/+ > M/M/+ > M/Df > M/M, where M represents the dominant mutant allele. PMID:2379819

  12. [Diseases caused by mutations in mitochondrial DNA].

    PubMed

    Wojewoda, Marta; Zabłocki, Krzysztof; Szczepanowska, Joanna

    2011-01-01

    Mitochondrial diseases associated with mutations within mitochondrial genome are a subgroup of metabolic disorders since their common consequence is reduced metabolic efficiency caused by impaired oxidative phophorylation and shortage of ATP. Although the vast majority of mitochondrial proteins (approximately 1500) is encoded by nuclear genome, mtDNA encodes 11 subunits of respiratory chain complexes, 2 subunits of ATP synthase, 22 tRNAs and 2 rRNAs. Up to now, more than 250 pathogenic mutations have been described within mtDNA. The most common are point mutations in genes encoding mitochondrial tRNAs such as 3243A-->G and 8344T-->G that cause, respectively, MELAS (mitochondrial encephalopathy, lactic acidosis and stroke-like episodes) or MIDD (maternally-inherited diabetes and deafness) and MERRF (myoclonic epilepsy with ragged red fibres) syndromes. There have been also found mutations in genes encoding subunits of ATP synthase such as 8993T-->G substitution associated with NARP (neuropathy, ataxia and retinitis pigmentosa) syndrome. It is worth to note that mitochondrial dysfunction can also be caused by mutations within nuclear genes coding for mitochondrial proteins. PMID:21913424

  13. Mutation spectrum of EYS in Spanish patients with autosomal recessive retinitis pigmentosa.

    PubMed

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

    2010-11-01

    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 space maker (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. PMID:21069908

  14. 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

  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. Mutation in WNT10A is associated with an autosomal recessive ectodermal dysplasia: the odonto-onycho-dermal dysplasia.

    PubMed

    Adaimy, Lynn; Chouery, Eliane; Megarbane, Hala; Mroueh, Salman; Delague, Valerie; Nicolas, Elsa; Belguith, Hanen; de Mazancourt, Philippe; Megarbane, Andre

    2007-10-01

    Odonto-onycho-dermal dysplasia is a rare autosomal recessive syndrome in which the presenting phenotype is dry hair, severe hypodontia, smooth tongue with marked reduction of fungiform and filiform papillae, onychodysplasia, keratoderma and hyperhidrosis of palms and soles, and hyperkeratosis of the skin. We studied three consanguineous Lebanese Muslim Shiite families that included six individuals affected with odonto-onycho-dermal dysplasia. Using a homozygosity-mapping strategy, we assigned the disease locus to an ~9-cM region at chromosome 2q35-q36.2, located between markers rs16853834 and D2S353, with a maximum multipoint LOD score of 5.7. Screening of candidate genes in this region led us to identify the same c.697G-->T (p.Glu233X) homozygous nonsense mutation in exon 3 of the WNT10A gene in all patients. At the protein level, the mutation is predicted to result in a premature truncated protein of 232 aa instead of 417 aa. This is the first report to our knowledge of a human phenotype resulting from a mutation in WNT10A, and it is the first demonstration of an ectodermal dysplasia caused by an altered WNT signaling pathway, expanding the list of WNT-related diseases. PMID:17847007

  17. Mutation in WNT10A Is Associated with an Autosomal Recessive Ectodermal Dysplasia: The Odonto-onycho-dermal Dysplasia

    PubMed Central

    Adaimy, Lynn ; Chouery, Eliane ; Mégarbané, Hala ; Mroueh, Salman ; Delague, Valérie ; Nicolas, Elsa ; Belguith, Hanen ; de Mazancourt, Philippe ; Mégarbané, André 

    2007-01-01

    Odonto-onycho-dermal dysplasia is a rare autosomal recessive syndrome in which the presenting phenotype is dry hair, severe hypodontia, smooth tongue with marked reduction of fungiform and filiform papillae, onychodysplasia, keratoderma and hyperhidrosis of palms and soles, and hyperkeratosis of the skin. We studied three consanguineous Lebanese Muslim Shiite families that included six individuals affected with odonto-onycho-dermal dysplasia. Using a homozygosity-mapping strategy, we assigned the disease locus to an ∼9-cM region at chromosome 2q35-q36.2, located between markers rs16853834 and D2S353, with a maximum multipoint LOD score of 5.7. Screening of candidate genes in this region led us to identify the same c.697G→T (p.Glu233X) homozygous nonsense mutation in exon 3 of the WNT10A gene in all patients. At the protein level, the mutation is predicted to result in a premature truncated protein of 232 aa instead of 417 aa. This is the first report to our knowledge of a human phenotype resulting from a mutation in WNT10A, and it is the first demonstration of an ectodermal dysplasia caused by an altered WNT signaling pathway, expanding the list of WNT-related diseases. PMID:17847007

  18. 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

  19. RAD21 Mutations Cause a Human Cohesinopathy

    PubMed Central

    Deardorff, Matthew A.; Wilde, Jonathan J.; Albrecht, Melanie; Dickinson, Emma; Tennstedt, Stephanie; Braunholz, Diana; Mönnich, Maren; Yan, Yuqian; Xu, Weizhen; Gil-Rodríguez, María Concepcion; Clark, Dinah; Hakonarson, Hakon; Halbach, Sara; Michelis, Laura Daniela; Rampuria, Abhinav; Rossier, Eva; Spranger, Stephanie; Van Maldergem, Lionel; Lynch, Sally Ann; Gillessen-Kaesbach, Gabriele; Lüdecke, Hermann-Josef; Ramsay, Robert G.; McKay, Michael J.; Krantz, Ian D.; Xu, Huiling; Horsfield, Julia A.; Kaiser, Frank J.

    2012-01-01

    The evolutionarily conserved cohesin complex was originally described for its role in regulating sister-chromatid cohesion during mitosis and meiosis. Cohesin and its regulatory proteins have been implicated in several human developmental disorders, including Cornelia de Lange (CdLS) and Roberts syndromes. Here we show that human mutations in the integral cohesin structural protein RAD21 result in a congenital phenotype consistent with a “cohesinopathy.” Children with RAD21 mutations display growth retardation, minor skeletal anomalies, and facial features that overlap findings in individuals with CdLS. Notably, unlike children with mutations in NIPBL, SMC1A, or SMC3, these individuals have much milder cognitive impairment than those with classical CdLS. Mechanistically, these mutations act at the RAD21 interface with the other cohesin proteins STAG2 and SMC1A, impair cellular DNA damage response, and disrupt transcription in a zebrafish model. Our data suggest that, compared to loss-of-function mutations, dominant missense mutations result in more severe functional defects and cause worse structural and cognitive clinical findings. These results underscore the essential role of RAD21 in eukaryotes and emphasize the need for further understanding of the role of cohesin in human development. PMID:22633399

  20. A rare cause of gingival recession: morphea with intra-oral involvement.

    PubMed

    Van der Veken, Dominique; De Haes, Petra; Hauben, Esther; Teughels, Wim; Lambrechts, Paul

    2015-05-01

    Morphea is an inflammatory disorder of the skin and underlying tissues characterized by an overabundance of collagen leading to fibrosis. The prevalence of this disease is estimated at around 0.4-2.7/100,000 people. When the process occurs in the gingival tissues, it induces traction, which can cause gingival recession. A 19-year-old woman was referred to the clinic for a progressive recession on teeth 11 and 12. A pale, atrophic, linear region extending from her nose to her upper lip on the right-hand side of her face was diagnosed as morphea en coup de sabre. Cone beam computed tomography, quantitative polymerase chain reaction and histologic evaluation were used to assess the pathology. Treatment with methotrexate was conducted. After 12 months, no progression of the recession could be observed. PMID:25864825

  1. 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

  2. A novel nonsense mutation in the WFS1 gene causes the Wolfram syndrome.

    PubMed

    Noorian, Shahab; Savad, Shahram; Mohammadi, Davood Shah

    2016-05-01

    Wolfram syndrome is a rare autosomal recessive neurodegenerative disorder, which is mostly caused by mutations in the WFS1 gene. The WFS1 gene product, which is called wolframin, is thought to regulate the function of endoplasmic reticulum. The endoplasmic reticulum has a critical role in protein folding and material transportation within the cell or to the surface of the cell. Identification of new mutations in WFS1 gene will unravel the molecular pathology of WS. The aim of this case report study is to describe a novel mutation in exon 4 of the WFS1 gene (c.330C>A) in a 9-year-old boy with WS. PMID:26943604

  3. Novel FGF8 Mutations Associated with Recessive Holoprosencephaly, Craniofacial Defects, and Hypothalamo-Pituitary Dysfunction

    PubMed Central

    McCabe, Mark J.; Gaston-Massuet, Carles; Tziaferi, Vaitsa; Gregory, Louise C.; Alatzoglou, Kyriaki S.; Signore, Massimo; Puelles, Eduardo; Gerrelli, Dianne; Farooqi, I. Sadaf; Raza, Jamal; Walker, Joanna; Kavanaugh, Scott I.; Tsai, Pei-San; Pitteloud, Nelly; Martinez-Barbera, Juan-Pedro

    2011-01-01

    Context: Fibroblast growth factor (FGF) 8 is important for GnRH neuronal development with human mutations resulting in Kallmann syndrome. Murine data suggest a role for Fgf8 in hypothalamo-pituitary development; however, its role in the etiology of wider hypothalamo-pituitary dysfunction in humans is unknown. Objective: The objective of this study was to screen for FGF8 mutations in patients with septo-optic dysplasia (n = 374) or holoprosencephaly (HPE)/midline clefts (n = 47). Methods: FGF8 was analyzed by PCR and direct sequencing. Ethnically matched controls were then screened for mutated alleles (n = 480–686). Localization of Fgf8/FGF8 expression was analyzed by in situ hybridization in developing murine and human embryos. Finally, Fgf8 hypomorphic mice (Fgf8loxPNeo/−) were analyzed for the presence of forebrain and hypothalamo-pituitary defects. Results: A homozygous p.R189H mutation was identified in a female patient of consanguineous parentage with semilobar HPE, diabetes insipidus, and TSH and ACTH insufficiency. Second, a heterozygous p.Q216E mutation was identified in a female patient with an absent corpus callosum, hypoplastic optic nerves, and Moebius syndrome. FGF8 was expressed in the ventral diencephalon and anterior commissural plate but not in Rathke's pouch, strongly suggesting early onset hypothalamic and corpus callosal defects in these patients. This was consolidated by significantly reduced vasopressin and oxytocin staining neurons in the hypothalamus of Fgf8 hypomorphic mice compared with controls along with variable hypothalamo-pituitary defects and HPE. Conclusion: We implicate FGF8 in the etiology of recessive HPE and potentially septo-optic dysplasia/Moebius syndrome for the first time to our knowledge. Furthermore, FGF8 is important for the development of the ventral diencephalon, hypothalamus, and pituitary. PMID:21832120

  4. Mutations in ANTXR1 cause GAPO syndrome.

    PubMed

    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

    2013-05-01

    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

  5. Whole-Exome Sequencing Efficiently Detects Rare Mutations in Autosomal Recessive Nonsyndromic Hearing Loss

    PubMed Central

    Diaz-Horta, Oscar; Duman, Duygu; Foster, Joseph; Sırmacı, Aslı; Gonzalez, Michael; Mahdieh, Nejat; Fotouhi, Nikou; Bonyadi, Mortaza; Cengiz, Filiz Başak; Menendez, Ibis; Ulloa, Rick H.; Edwards, Yvonne J. K.; Züchner, Stephan; Blanton, Susan; Tekin, Mustafa

    2012-01-01

    Identification of the pathogenic mutations underlying autosomal recessive nonsyndromic hearing loss (ARNSHL) is difficult, since causative mutations in 39 different genes have so far been reported. After excluding mutations in the most common ARNSHL gene, GJB2, via Sanger sequencing, we performed whole-exome sequencing (WES) in 30 individuals from 20 unrelated multiplex consanguineous families with ARNSHL. Agilent SureSelect Human All Exon 50 Mb kits and an Illumina Hiseq2000 instrument were used. An average of 93%, 84% and 73% of bases were covered to 1X, 10X and 20X within the ARNSHL-related coding RefSeq exons, respectively. Uncovered regions with WES included those that are not targeted by the exome capture kit and regions with high GC content. Twelve homozygous mutations in known deafness genes, of which eight are novel, were identified in 12 families: MYO15A-p.Q1425X, -p.S1481P, -p.A1551D; LOXHD1-p.R1494X, -p.E955X; GIPC3-p.H170N; ILDR1-p.Q274X; MYO7A-p.G2163S; TECTA-p.Y1737C; TMC1-p.S530X; TMPRSS3-p.F13Lfs*10; TRIOBP-p.R785Sfs*50. Each mutation was within a homozygous run documented via WES. Sanger sequencing confirmed co-segregation of the mutation with deafness in each family. Four rare heterozygous variants, predicted to be pathogenic, in known deafness genes were detected in 12 families where homozygous causative variants were already identified. Six heterozygous variants that had similar characteristics to those abovementioned variants were present in 15 ethnically-matched individuals with normal hearing. Our results show that rare causative mutations in known ARNSHL genes can be reliably identified via WES. The excess of heterozygous variants should be considered during search for causative mutations in ARNSHL genes, especially in small-sized families. PMID:23226338

  6. TNXB mutations can cause vesicoureteral reflux.

    PubMed

    Gbadegesin, Rasheed A; Brophy, Patrick D; Adeyemo, Adebowale; Hall, Gentzon; Gupta, Indra R; Hains, David; Bartkowiak, Bartlomeij; Rabinovich, C Egla; Chandrasekharappa, Settara; Homstad, Alison; Westreich, Katherine; Wu, Guanghong; Liu, Yutao; Holanda, Danniele; Clarke, Jason; Lavin, Peter; Selim, Angelica; Miller, Sara; Wiener, John S; Ross, Sherry S; Foreman, John; Rotimi, Charles; Winn, Michelle P

    2013-07-01

    Primary vesicoureteral reflux (VUR) is the most common congenital anomaly of the kidney and the urinary tract, and it is a major risk factor for pyelonephritic scarring and CKD in children. Although twin studies support the heritability of VUR, specific genetic causes remain elusive. We performed a sequential genome-wide linkage study and whole-exome sequencing in a family with hereditary VUR. We obtained a significant multipoint parametric logarithm of odds score of 3.3 on chromosome 6p, and whole-exome sequencing identified a deleterious heterozygous mutation (T3257I) in the gene encoding tenascin XB (TNXB in 6p21.3). This mutation segregated with disease in the affected family as well as with a pathogenic G1331R change in another family. Fibroblast cell lines carrying the T3257I mutation exhibited a reduction in both cell motility and phosphorylated focal adhesion kinase expression, suggesting a defect in the focal adhesions that link the cell cytoplasm to the extracellular matrix. Immunohistochemical studies revealed that the human uroepithelial lining of the ureterovesical junction expresses TNXB, suggesting that TNXB may be important for generating tensile forces that close the ureterovesical junction during voiding. Taken together, these results suggest that mutations in TNXB can cause hereditary VUR. PMID:23620400

  7. Novel splice site mutation in the caveolin-3 gene leading to autosomal recessive limb girdle muscular dystrophy.

    PubMed

    Müller, Juliane S; Piko, Henriett; Schoser, Benedikt G H; Schlotter-Weigel, Beate; Reilich, Peter; Gürster, Stefanie; Born, Christine; Karcagi, Veronika; Pongratz, Dieter; Lochmüller, Hanns; Walter, Maggie C

    2006-07-01

    Mutations in CAV3 gene encoding the protein caveolin-3 are associated with autosomal dominant limb girdle muscular dystrophy 1C, rippling muscle disease, hyperCKemia, distal myopathy, hypertrophic cardiomyopathy and rare autosomal recessive limb girdle muscular dystrophy phenotypes. In a 57-year-old patient with asymmetric limb girdle weakness, we detected a novel homozygous intronic mutation (IVS1 + 2T > C) of the CAV3 gene. This is the first splicing mutation reported for CAV3. These findings add to the clinical and genetic variability of CAV3 mutations. PMID:16730439

  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 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.

  10. Targeted Next-Generation Sequencing of a 12.5 Mb Homozygous Region Reveals ANO10 Mutations in Patients with Autosomal-Recessive Cerebellar Ataxia

    PubMed Central

    Vermeer, Sascha; Hoischen, Alexander; Meijer, Rowdy P.P.; Gilissen, Christian; Neveling, Kornelia; Wieskamp, Nienke; de Brouwer, Arjan; Koenig, Michel; Anheim, Mathieu; Assoum, Mirna; Drouot, Nathalie; Todorovic, Slobodanka; Milic-Rasic, Vedrana; Lochmüller, Hanns; Stevanin, Giovanni; Goizet, Cyril; David, Albert; Durr, Alexandra; Brice, Alexis; Kremer, Berry; van de Warrenburg, Bart P.C.; Schijvenaars, Mascha M.V.A.P.; Heister, Angelien; Kwint, Michael; Arts, Peer; van der Wijst, Jenny; Veltman, Joris; Kamsteeg, Erik-Jan; Scheffer, Hans; Knoers, Nine

    2010-01-01

    Autosomal-recessive cerebellar ataxias comprise a clinically and genetically heterogeneous group of neurodegenerative disorders. In contrast to their dominant counterparts, unraveling the molecular background of these ataxias has proven to be more complicated and the currently known mutations provide incomplete coverage for genotyping of patients. By combining SNP array-based linkage analysis and targeted resequencing of relevant sequences in the linkage interval with the use of next-generation sequencing technology, we identified a mutation in a gene and have shown its association with autosomal-recessive cerebellar ataxia. In a Dutch consanguineous family with three affected siblings a homozygous 12.5 Mb region on chromosome 3 was targeted by array-based sequence capture. Prioritization of all detected sequence variants led to four candidate genes, one of which contained a variant with a high base pair conservation score (phyloP score: 5.26). This variant was a leucine-to-arginine substitution in the DUF 590 domain of a 16K transmembrane protein, a putative calcium-activated chloride channel encoded by anoctamin 10 (ANO10). The analysis of ANO10 by Sanger sequencing revealed three additional mutations: a homozygous mutation (c.1150_1151del [p.Leu384fs]) in a Serbian family and a compound-heterozygous splice-site mutation (c.1476+1G>T) and a frameshift mutation (c.1604del [p.Leu535X]) in a French family. This illustrates the power of using initial homozygosity mapping with next-generation sequencing technology to identify genes involved in autosomal-recessive diseases. Moreover, identifying a putative calcium-dependent chloride channel involved in cerebellar ataxia adds another pathway to the list of pathophysiological mechanisms that may cause cerebellar ataxia. PMID:21092923

  11. Feline acute intermittent porphyria: a phenocopy masquerading as an erythropoietic porphyria due to dominant and recessive hydroxymethylbilane synthase mutations

    PubMed Central

    Clavero, Sonia; Bishop, David F.; Haskins, Mark E.; Giger, Urs; Kauppinen, Raili; Desnick, Robert J.

    2010-01-01

    Human acute intermittent porphyria (AIP), the most common acute hepatic porphyria, is an autosomal dominant inborn error of heme biosynthesis due to the half-normal activity of hydroxymethylbilane synthase (HMB-synthase). Here, we describe the first naturally occurring animal model of AIP in four unrelated cat lines who presented phenotypically as congenital erythropoietic porphyria (CEP). Affected cats had erythrodontia, brownish urine, fluorescent bones, and markedly elevated urinary uroporphyrin (URO) and coproporphyrin (COPRO) consistent with CEP. However, their uroporphyrinogen-III-synthase (URO-synthase) activities (deficient in CEP) were normal. Notably, affected cats had half-normal HMB-synthase activities and elevated urinary 5-aminolevulinic acid (ALA) and porphobilinogen (PBG), the deficient enzyme and accumulated metabolites in human AIP. Sequencing the feline HMB-synthase gene revealed different mutations in each line: a duplication (c.189dupT), an in-frame 3 bp deletion (c.842_844delGAG) identical to that causing human AIP and two missense mutations, c.250G>A (p.A84T) and c.445C>T (p.R149W). Prokaryotic expression of mutations c.842_844delGAG and c.445C>T resulted in mutant enzymes with <1% wild-type activity, whereas c.250G>A expressed a stable enzyme with ∼35% of wild-type activity. The discolored teeth from the affected cats contained markedly elevated URO I and III, accounting for the CEP-like phenocopy. In three lines, the phenotype was an autosomal dominant trait, while affected cats with the c.250G>A (p.A84T) mutation were homozygous, a unique recessive form of AIP. These animal models may permit further investigation of the pathogenesis of the acute, life-threatening neurological attacks in human AIP and the evaluation of therapeutic strategies. GenBank Accession Numbers: GQ850461–GQ850464. PMID:19934113

  12. A homozygous parkin p.G284R mutation in a Chinese family with autosomal recessive juvenile parkinsonism.

    PubMed

    Chen, Han; Huang, Xiangjun; Yuan, Lamei; Xia, Hong; Xu, Hongbo; Yang, Yan; Zheng, Wen; Deng, Hao

    2016-06-15

    Autosomal recessive juvenile parkinsonism (AR-JP) is a distinct clinical and neuropathologic entity characterized by early onset parkinsonism and localized neuronal degeneration in the substantia nigra without Lewy bodies. The purpose of this study is to identify the genetic defect in a Chinese pedigree with familial AR-JP and to explore genotype-phenotype correlation. A three-generation Chinese Han pedigree with familial AR-JP was recruited in this study, and the patients in the pedigree presented with typical but heterogeneous clinical features of AR-JP and with different ages of disease onset. Exome sequencing and Sanger sequencing were conducted in the index case diagnosed as juvenile parkinsonism and a homozygous variant, c.850G>C (p.G284R), in the parkin gene was identified. The homozygous variant co-segregated with the disease in the family and was absent in 800 controls. The homozygous variant, c.850G>C (p.G284R), in the parkin gene is possibly responsible for AR-JP in this pedigree. Heterozygous c.850G>C mutation carriers were free of any neurological symptoms, consistent with a loss-of-function mechanism of the parkin mutations. These findings may provide new insights into the cause and diagnosis of AR-JP and have implications for genetic counseling. PMID:27177722

  13. 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

  14. Seventeen novel mutations that cause profound biotinidase deficiency.

    PubMed

    Wolf, B; Jensen, K; Hüner, G; Demirkol, M; Baykal, T; Divry, P; Rolland, M-O; Perez-Cerdá, C; Ugarte, M; Straussberg, R; Basel-Vanagaite, L; Baumgartner, E R; Suormala, T; Scholl, S; Das, A M; Schweitzer, S; Pronicka, E; Sykut-Cegielska, J

    2002-01-01

    We report 17 novel mutations that cause profound biotinidase deficiency. Six of the mutations are due to deletions, whereas the remaining 11 mutations are missense mutations located throughout the gene and encode amino acids that are conserved in mammals. Our results increase the total number of different mutations that cause biotinidase deficiency to 79. These additional mutations will undoubtedly be helpful in identifying structure/function relationships once the three-dimensional structure of biotinidase is determined. PMID:12359137

  15. Simple recessive mutation in ENAM is associated with amelogenesis imperfecta in Italian Greyhounds.

    PubMed

    Gandolfi, Barbara; Liu, Hongwei; Griffioen, Layle; Pedersen, Niels C

    2013-08-01

    We report a familial enamel hypoplasia in Italian Greyhounds resembling non-syndromic autosomal recessive amelogenesis imperfecta (AI) of humans. The condition uniformly affects deciduous and permanent teeth and is manifested by enamel roughening/thinning and brownish mottling. Affected teeth are often small and pointed with increased gaps. However, basic tooth structure is usually maintained throughout life, and fractures and dental cavities are not a serious problem as in humans. No tissues or organs other than teeth were affected by this mutation, and there was no relationship between enamel hypoplasia and either autoimmunity or periodontal disease, which also are prevalent in the breed. The enamel hypoplasia was associated with a 5-bp deletion in exon 10 of the enamelin (ENAM) gene. The prevalence of the enamel defect in Italian Greyhounds was 14%, and 30% of dogs with normal teeth were carriers. Genome analyses suggest that the trait is under inadvertent positive selection. Based on the deletion detected in the ENAM gene, a genetic test was developed for identifying mutation carriers, which would enable breeders to manage the trait. PMID:23638899

  16. Germline recessive mutations in PI4KA are associated with perisylvian polymicrogyria, cerebellar hypoplasia and arthrogryposis

    PubMed Central

    Pagnamenta, Alistair T.; Howard, Malcolm F.; Wisniewski, Eva; Popitsch, Niko; Knight, Samantha J.L.; Keays, David A.; Quaghebeur, Gerardine; Cox, Helen; Cox, Phillip; Balla, Tamas; Taylor, Jenny C.; Kini, Usha

    2015-01-01

    Polymicrogyria (PMG) is a structural brain abnormality involving the cerebral cortex that results from impaired neuronal migration and although several genes have been implicated, many cases remain unsolved. In this study, exome sequencing in a family where three fetuses had all been diagnosed with PMG and cerebellar hypoplasia allowed us to identify regions of the genome for which both chromosomes were shared identical-by-descent, reducing the search space for causative variants to 8.6% of the genome. In these regions, the only plausibly pathogenic mutations were compound heterozygous variants in PI4KA, which Sanger sequencing confirmed segregated consistent with autosomal recessive inheritance. The paternally transmitted variant predicted a premature stop mutation (c.2386C>T; p.R796X), whereas the maternally transmitted variant predicted a missense substitution (c.5560G>A; p.D1854N) at a conserved residue within the catalytic domain. Functional studies using expressed wild-type or mutant PI4KA enzyme confirmed the importance of p.D1854 for kinase activity. Our results emphasize the importance of phosphoinositide signalling in early brain development. PMID:25855803

  17. NEK8 mutations affect ciliary and centrosomal localization and may cause nephronophthisis.

    PubMed

    Otto, Edgar A; Trapp, Melissa L; Schultheiss, Ulla T; Helou, Juliana; Quarmby, Lynne M; Hildebrandt, Friedhelm

    2008-03-01

    Nephronophthisis, an autosomal recessive kidney disease, is the most frequent genetic cause of chronic renal failure in the first 3 decades of life. Causative mutations in 8 genes (NPHP1-8) have been identified, and homologous mouse models for NPHP2/INVS and NPHP3 have been described. The jck mouse is another model of recessive cystic kidney disease, and this mouse harbors a missense mutation, G448V, in the highly conserved RCC1 domain of Nek8. We hypothesized that mutations in NEK8 might cause nephronophthisis in humans, so we performed mutational analysis in a worldwide cohort of 588 patients. We identified 3 different amino acid changes that were conserved through evolution (L330F, H425Y, and A497P) and that were absent from at least 80 ethnically matched controls. All 3 mutations were within RCC1 domains, and the mutation H425Y was positioned within the same RCC1 repeat as the mouse jck mutation. To test the functional significance of these mutations, we introduced them into full-length mouse Nek8 GFP-tagged cDNA constructs. We transiently overexpressed the constructs in inner medullary collecting duct cells (IMCD-3 cell line) and compared the subcellular localization of mutant Nek8 to wild-type Nek8. All mutant forms of Nek8 showed defects in ciliary localization to varying degrees; the H431Y mutant (human H425Y) was completely absent from cilia and the amount localized to centrosomes was decreased. Overexpression of these mutants did not affect overall ciliogenesis, mitosis, or centriole number. Our genetic and functional data support the assumption that mutations in NEK8 cause nephronophthisis (NPHP9), adding another link between proteins mutated in cystic kidney disease and their localization to cilia and centrosomes. PMID:18199800

  18. Recessive TTN truncating mutations define novel forms of core myopathy with heart disease

    PubMed Central

    Chauveau, Claire; Bonnemann, Carsten G.; Julien, Cedric; Kho, Ay Lin; Marks, Harold; Talim, Beril; Maury, Philippe; Arne-Bes, Marie Christine; Uro-Coste, Emmanuelle; Alexandrovich, Alexander; Vihola, Anna; Schafer, Sebastian; Kaufmann, Beth; Medne, Livija; Hübner, Norbert; Foley, A. Reghan; Santi, Mariarita; Udd, Bjarne; Topaloglu, Haluk; Moore, Steven A.; Gotthardt, Michael; Samuels, Mark E.; Gautel, Mathias; Ferreiro, Ana

    2014-01-01

    Core myopathies (CM), the main non-dystrophic myopathies in childhood, remain genetically unexplained in many cases. Heart disease is not considered part of the typical CM spectrum. No congenital heart defect has been reported, and childhood-onset cardiomyopathy has been documented in only two CM families with homozygous mutations of the TTN gene. TTN encodes titin, a giant protein of striated muscles. Recently, heterozygous TTN truncating mutations have also been reported as a major cause of dominant dilated cardiomyopathy. However, relatively few TTN mutations and phenotypes are known, and titin pathophysiological role in cardiac and skeletal muscle conditions is incompletely understood. We analyzed a series of 23 families with congenital CM and primary heart disease using TTN M-line-targeted sequencing followed in selected patients by whole-exome sequencing and functional studies. We identified seven novel homozygous or compound heterozygous TTN mutations (five in the M-line, five truncating) in 17% patients. Heterozygous parents were healthy. Phenotype analysis identified four novel titinopathies, including cardiac septal defects, left ventricular non-compaction, Emery–Dreifuss muscular dystrophy or arthrogryposis. Additionally, in vitro studies documented the first-reported absence of a functional titin kinase domain in humans, leading to a severe antenatal phenotype. We establish that CM are associated with a large range of heart conditions of which TTN mutations are a major cause, thereby expanding the TTN mutational and phenotypic spectrum. Additionally, our results suggest titin kinase implication in cardiac morphogenesis and demonstrate that heterozygous TTN truncating mutations may not manifest unless associated with a second mutation, reassessing the paradigm of their dominant expression. PMID:24105469

  19. Recessive TTN truncating mutations define novel forms of core myopathy with heart disease.

    PubMed

    Chauveau, Claire; Bonnemann, Carsten G; Julien, Cedric; Kho, Ay Lin; Marks, Harold; Talim, Beril; Maury, Philippe; Arne-Bes, Marie Christine; Uro-Coste, Emmanuelle; Alexandrovich, Alexander; Vihola, Anna; Schafer, Sebastian; Kaufmann, Beth; Medne, Livija; Hübner, Norbert; Foley, A Reghan; Santi, Mariarita; Udd, Bjarne; Topaloglu, Haluk; Moore, Steven A; Gotthardt, Michael; Samuels, Mark E; Gautel, Mathias; Ferreiro, Ana

    2014-02-15

    Core myopathies (CM), the main non-dystrophic myopathies in childhood, remain genetically unexplained in many cases. Heart disease is not considered part of the typical CM spectrum. No congenital heart defect has been reported, and childhood-onset cardiomyopathy has been documented in only two CM families with homozygous mutations of the TTN gene. TTN encodes titin, a giant protein of striated muscles. Recently, heterozygous TTN truncating mutations have also been reported as a major cause of dominant dilated cardiomyopathy. However, relatively few TTN mutations and phenotypes are known, and titin pathophysiological role in cardiac and skeletal muscle conditions is incompletely understood. We analyzed a series of 23 families with congenital CM and primary heart disease using TTN M-line-targeted sequencing followed in selected patients by whole-exome sequencing and functional studies. We identified seven novel homozygous or compound heterozygous TTN mutations (five in the M-line, five truncating) in 17% patients. Heterozygous parents were healthy. Phenotype analysis identified four novel titinopathies, including cardiac septal defects, left ventricular non-compaction, Emery-Dreifuss muscular dystrophy or arthrogryposis. Additionally, in vitro studies documented the first-reported absence of a functional titin kinase domain in humans, leading to a severe antenatal phenotype. We establish that CM are associated with a large range of heart conditions of which TTN mutations are a major cause, thereby expanding the TTN mutational and phenotypic spectrum. Additionally, our results suggest titin kinase implication in cardiac morphogenesis and demonstrate that heterozygous TTN truncating mutations may not manifest unless associated with a second mutation, reassessing the paradigm of their dominant expression. PMID:24105469

  20. 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

  1. 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

  2. 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

  3. 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

  4. 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

  5. CO-OCCURRENCE OF PRIMARY MICROCEPHALY CAUSED BY A NOVEL HOMOZYGOUS ASPM MUTATION ALONG WITH X-LINKED ICHTHYOSIS IN THE SAME PATIENT.

    PubMed

    Abdel-Hamid, M S; Ismail, M F; Darwish, H A; Effat, L K; Zaki, M S; Abdel-Salam, G M H

    2016-01-01

    Autosomal recessive primary microcephaly is a heterogeneous genetic disorder caused by genes that affect neurogenesis. This form of microcephaly has not been associated with other congenital anomalies. ASPM mutations have been identified as the major cause implicated in autosomal recessive primary microcephaly. X-linked recessive ichthyosis, is an inborn error of steroid sulfatase metabolism characterized by dark and adhesive scaly skin. Here, we examined an Egyptian boy presenting with microcephaly and simplified gyral pattern. Additionally, he had ichthyosis that goes with the X-linked type. Mutation analyses of the ASPM gene for autosomal recessive primary microcephaly and STS gene of X-linked recessive ichthyosis were conducted revealing a co-occurrence of a novel homozygous splice site mutation of ASPM gene (c.2936+1G>A) and a partial deletion of STS spanning from exon 7-10. We propose that the phenotype of our patient results from the combined effects of mutations in both ASPM and STS that account for the neurological signs and skin manifestations, respectively. The association of isolated X-linked recessive ichthyosis and autosomal recessive primary microcephaly has never been reported in the literature. Careful clinical and genetic assessment of patients with atypical clinical phenotypes is crucial for detecting such rare double mutations and thus proper genetic counseling. PMID:27192889

  6. 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

  7. nm1054: a spontaneous, recessive, hypochromic, microcytic anemia mutation in the mouse.

    PubMed

    Ohgami, Robert S; Campagna, Dean R; Antiochos, Brendan; Wood, Emily B; Sharp, John J; Barker, Jane E; Fleming, Mark D

    2005-11-15

    Hypochromic, microcytic anemias are typically the result of inadequate hemoglobin production because of globin defects or iron deficiency. Here, we describe the phenotypic characteristics and pathogenesis of a new recessive, hypochromic, microcytic anemia mouse mutant, nm1054. Although the mutation nm1054 is pleiotropic, also resulting in sparse hair, male infertility, failure to thrive, and hydrocephaly, the anemia is the focus of this study. Hematologic analysis reveals a moderately severe, congenital, hypochromic, microcytic anemia, with an elevated red cell zinc protoporphyrin, consistent with functional erythroid iron deficiency. However, serum and tissue iron analyses show that nm1054 animals are not systemically iron deficient. From hematopoietic stem cell transplantation and iron uptake studies in nm1054 reticulocytes, we provide evidence that the nm1054 anemia is due to an intrinsic hematopoietic defect resulting in inefficient transferrin-dependent iron uptake by erythroid precursors. Linkage studies demonstrate that nm1054 maps to a genetic locus not previously implicated in microcytic anemia or iron phenotypes. PMID:15994289

  8. Polyhydramnios and cerebellar atrophy: a prenatal presentation of mitochondrial encephalomyopathy caused by mutations in the FBXL4 gene.

    PubMed

    van Rij, Maartje C; Jansen, Fenna A R; Hellebrekers, Debby M E I; Onkenhout, W; Smeets, Hubert J M; Hendrickx, Alexandra T; Gottschalk, Ralph W H; Steggerda, Sylke J; Peeters-Scholte, Cacha M P C D; Haak, Monique C; Hilhorst-Hofstee, Yvonne

    2016-04-01

    Severe recessive mitochondrial myopathy caused by FBXL4 gene mutations may present prenatally with polyhydramnios and cerebellar hypoplasia. Characteristic dysmorphic features are: high and arched eyebrows, triangular face, a slight upslant of palpebral fissures, and a prominent pointed chin. Metabolic investigations invariably show increased serum lactate and pyruvate levels. PMID:27099744

  9. 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...

  10. 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

  11. Commonality of TRIM32 mutation in causing sarcotubular myopathy and LGMD2H.

    PubMed

    Schoser, Benedikt G H; Frosk, Patrick; Engel, Andrew G; Klutzny, Ursula; Lochmüller, Hanns; Wrogemann, Klaus

    2005-04-01

    Sarcotubular myopathy (OMIM 268950) is a rare autosomal recessive myopathy first described in two Hutterite brothers from South Dakota and in two non-Hutterite brothers from Germany. We report that sarcotubular myopathy (STM) is caused by mutation in TRIM32, the gene encoding the tripartite motif-containing protein 32. TRIM32 was found to be the gene mutated in limb girdle muscular dystrophy type 2H (LGMD2H [OMIM 254110]), a disorder that has been confined to the Hutterite population. The TRIM32 mutation found in the STM patients is identical to the causative mutation for LGMD2H (D487N), Haplotype analysis shows that the disease chromosomes share common ancestry. PMID:15786463

  12. 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

  13. Characterization of mutations of the type VII collagen gene (COL7A1) in recessive dystrophic epidermolysis bullosa mitis (M-RDEB) from three Korean patients.

    PubMed

    Ryoo, Y W; Kim, B C; Lee, K S

    2001-06-01

    In recent years, the molecular basis for the main subtypes of epidermolysis bullosa (EB) has been elucidated with pathogenetic mutations delineated in ten different genes encoding structural components of the dermal-epidermal junction. Both the autosomal dominant and recessive forms of dystrophic EB (DEB) is caused by mutations in the COL7A1 gene. Type VII collagen is a major component of anchoring fibrils, structural elements that stabilize the attachment of the basement membrane to underlying dermis. Recent delineation of the exon-intron organization of the COL7A1 gene provided the basis for the comprehensive design of PCR primer pairs that amplified exons in genomic DNA by placing the primers on the flanking introns. A number of COL7A1 mutations have been reported and some genotype-phenotype correlations are starting to emerge. In this study, we examined mutational analyses from three Korean patients with recessive dystrophic EB (RDEB) mitis. We designed and optimized primers according to the previously reported sequences. Such PCR amplification products can be examined by electrophoretic scanning technique, CSGE heteroduplex analyses. Utilizing heteroduplex analyses, we have identified a number of sequence variants in COL7A1 both in unaffected individuals and in patients with M-RDEB. Mutation detection of the COL7A1 gene revealed six allelic mutations (V6677E, P6685S, Y3749S, P6084S, P6695R and G6697C). We suggest that the full length of type VII collagen polypeptide are synthesized, but those missense mutations, that may affect a critical amino acid, can alter the conformation of the protein and interferes with the assembly and packing of type VII collagen molecules into anchoring fibrils. Immunohistochemical study of skin biopsies by use of anti-type VII collagen antibody showed markedly reduced staining and presence of a dermo/epidermal cleavage. This is the first report of a COL7A1 mutation study in DEB from Korean patients. We hope that these data

  14. Mutations in SLC45A2 cause plumage color variation in chicken and Japanese quail.

    PubMed

    Gunnarsson, Ulrika; Hellström, Anders R; Tixier-Boichard, Michele; Minvielle, Francis; Bed'hom, Bertrand; Ito, Shin'ichi; Jensen, Per; Rattink, Annemieke; Vereijken, Addie; Andersson, Leif

    2007-02-01

    S*S (Silver), S*N (wild type/gold), and S*AL (sex-linked imperfect albinism) form a series of alleles at the S (Silver) locus on chicken (Gallus gallus) chromosome Z. Similarly, sex-linked imperfect albinism (AL*A) is the bottom recessive allele at the orthologous AL locus in Japanese quail (Coturnix japonica). The solute carrier family 45, member 2, protein (SLC45A2), previously denoted membrane-associated transporter protein (MATP), has an important role in vesicle sorting in the melanocytes. Here we report five SLC45A2 mutations. The 106delT mutation in the chicken S*AL allele results in a frameshift and a premature stop codon and the corresponding mRNA appears to be degraded by nonsense-mediated mRNA decay. A splice-site mutation in the Japanese quail AL*A allele causes in-frame skipping of exon 4. Two independent missense mutations (Tyr277Cys and Leu347Met) were associated with the Silver allele in chicken. The functional significance of the former mutation, associated only with Silver in White Leghorn, is unclear. Ala72Asp was associated with the cinnamon allele (AL*C) in the Japanese quail. The most interesting feature concerning the SLC45A2 variants documented in this study is the specific inhibition of expression of red pheomelanin in Silver chickens. This phenotypic effect cannot be explained on the basis of the current, incomplete, understanding of SLC45A2 function. It is an enigma why recessive null mutations at this locus cause an almost complete absence of both eumelanin and pheomelanin whereas some missense mutations are dominant and cause a specific inhibition of pheomelanin production. PMID:17151254

  15. stem fasciated, a Recessive Mutation in Sunflower (Helianthus annuus), Alters Plant Morphology and Auxin Level

    PubMed Central

    FAMBRINI, MARCO; BONSIGNORI, ELISA; RAPPARINI, FRANCESCA; CIONINI, GIULIANO; MICHELOTTI, VANIA; BERTINI, DANIELE; BARALDI, RITA; PUGLIESI, CLAUDIO

    2006-01-01

    • Background and Aims Plant lateral organs such as leaves arise from a group of initial cells within the flanks of the shoot apical meristem (SAM). Alterations in the initiation of lateral organs are often associated with changes in the dimension and arrangement of the SAM as well as with abnormal hormonal homeostasis. A mutation named stem fasciated (stf) that affects various aspects of plant development, including SAM shape and auxin level, was characterized in sunflower (Helianthus annuus). • Methods F1, F2 and F3 generations were obtained through reciprocal crosses between stf and normal plants. For the genetic analysis, a χ2 test was used. Phenotypic observations were made in field-grown and potted plants. A histological analysis of SAM, hypocotyl, epicotyl, stem and root apical meristem was also conducted. To evaluate the level of endogenous indole-3-acetic acid (IAA), a capillary gas chromatography–mass spectrometry–selected ion monitoring analysis was performed. • Key Results stf is controlled by a single nuclear recessive gene. stf plants are characterized by a dramatically increased number of leaves and vascular bundles in the stem, as well as by a shortened plastochron and an altered phyllotaxis pattern. By histological analysis, it was demonstrated that the stf phenotype is related to an enlarged vegetative SAM. Microscopy analysis of the mutant's apex also revealed an abnormal enlargement of nuclei in both central and peripheral zones and a disorganized distribution of cells in the L2 layer of the central zone. The stf mutant showed a high endogenous free IAA level, whereas auxin perception appeared normal. • Conclusions The observed phenotype and the high level of auxin detected in stf plants suggest that the STF gene is necessary for the proper initiation of primordia and for the establishment of a phyllotactic pattern through control of both SAM arrangement and hormonal homeostasis. PMID:16845141

  16. Do mutations in SCN1B cause Dravet syndrome?

    PubMed

    Kim, Young Ok; Dibbens, Leanne; Marini, Carla; Suls, Arvid; Chemaly, Nicole; Mei, Davide; McMahon, Jacinta M; Iona, Xenia; Berkovic, Samuel F; De Jonghe, Peter; Guerrini, Renzo; Nabbout, Rima; Scheffer, Ingrid E

    2013-01-01

    A homozygous SCN1B mutation was previously identified in a patient with early onset epileptic encephalopathy (EOEE) described as Dravet syndrome (DS) despite a more severe phenotype than DS. We investigated whether SCN1B mutations are a common cause of DS. Patients with DS who did not have a SCN1A sequencing mutation or copy number variation were studied. Genomic DNA was Sanger sequenced for mutations in the 6 exons of SCN1B. In 54 patients with DS recruited from four centres, no SCN1B mutations were identified. SCN1B mutation is not a common cause of DS. PMID:23182416

  17. Prevalence and range of GJB2 and SLC26A4 mutations in patients with autosomal recessive non‑syndromic hearing loss.

    PubMed

    Jiang, Hua; Chen, Jia; Shan, Xin-Ji; Li, Ying; He, Jian-Guo; Yang, Bei-Bei

    2014-07-01

    The frequency and distribution of genetic mutations that cause deafness differ significantly according to ethnic group and region. Zhejiang is a province in the southeast of China, with an exceptional racial composition of the population caused by mass migration in ancient China. The purpose of the present study was to investigate the prevalence and spectrum of gap junction‑β2 (GJB2), solute carrier family 26 (anion exchanger) member 4 (SLC26A4) and GJB3 mutations in patients with autosomal recessive non‑syndromic hearing loss (ARNHL) in this area. A total of 176 unrelated pediatric patients with ARNHL were enrolled in the study. A genomic DNA sample was extracted from the peripheral blood. Polymerase chain reaction was employed, and the products were sequenced to screen for mutations in GJB2. In addition, a SNaPshot sequencing method was utilized to detect four hotspot mutations in SLC26A4 (IVS7‑2A>G and c.2168A>G) and GJB3 (c.538C>T and c.547G>A). All patients were subjected to a temporal bone computed tomography scan to identify enlarged vestibular aqueducts (EVA). In total, 14 different mutations, including two new mutations (p.W44L and p.D66N) of GJB2, were detected. The most common pathogenic mutation of GJB2 was c.235delC (15.1%), followed by c.176_191del16 (1.7%), c.299_300delAT (1.7%), c.508_511dup (0.85%) and c.35delG (0.28%) of the total alleles. Mutation analysis of SLC26A4 demonstrated that 13.6% (24/176) of patients carried at least one mutant allele. The patients with EVA (84.2%) had SLC26A4 mutations, and 31% had homozygous mutations. Only one patient carried a heterozygous mutation of GJB3 (c.538C>T). Compared with the other regions of China, in the present population cohort, the prevalence and spectrum of mutations in GJB2 was unique, and in patients with EVA the frequency of a homozygous mutation in SLC26A4 was significantly lower. These findings may be of benefit in genetic counseling and risk assessment for families from this area of

  18. Canine Disorder Mirrors Human Disease: Exonic Deletion in HES7 Causes Autosomal Recessive Spondylocostal Dysostosis in Miniature Schnauzer Dogs

    PubMed Central

    Willet, Cali E.; Makara, Mariano; Reppas, George; Tsoukalas, George; Malik, Richard; Haase, Bianca; Wade, Claire M.

    2015-01-01

    Spondylocostal dysostosis is a congenital disorder of the axial skeleton documented in human families from diverse racial backgrounds. The condition is characterised by truncal shortening, extensive hemivertebrae and rib anomalies including malalignment, fusion and reduction in number. Mutations in the Notch signalling pathway genes DLL3, MESP2, LFNG, HES7 and TBX6 have been associated with this defect. In this study, spondylocostal dysostosis in an outbred family of miniature schnauzer dogs is described. Computed tomography demonstrated that the condition mirrors the skeletal defects observed in human cases, but unlike most human cases, the affected dogs were stillborn or died shortly after birth. Through gene mapping and whole genome sequencing, we identified a single-base deletion in the coding region of HES7. The frameshift mutation causes loss of functional domains essential for the oscillatory transcriptional autorepression of HES7 during somitogenesis. A restriction fragment length polymorphism test was applied within the immediate family and supported a highly penetrant autosomal recessive mode of inheritance. The mutation was not observed in wider testing of 117 randomly sampled adult miniature schnauzer and six adult standard schnauzer dogs; providing a significance of association of Praw = 4.759e-36 (genome-wide significant). Despite this apparently low frequency in the Australian population, the allele may be globally distributed based on its presence in two unrelated sires from geographically distant locations. While isolated hemivertebrae have been observed in a small number of other dog breeds, this is the first clinical and genetic diagnosis of spontaneously occurring spondylocostal dysostosis in a non-human mammal and offers an excellent model in which to study this devastating human disorder. The genetic test can be utilized by dog breeders to select away from the disease and avoid unnecessary neonatal losses. PMID:25659135

  19. Canine disorder mirrors human disease: exonic deletion in HES7 causes autosomal recessive spondylocostal dysostosis in miniature Schnauzer dogs.

    PubMed

    Willet, Cali E; Makara, Mariano; Reppas, George; Tsoukalas, George; Malik, Richard; Haase, Bianca; Wade, Claire M

    2015-01-01

    Spondylocostal dysostosis is a congenital disorder of the axial skeleton documented in human families from diverse racial backgrounds. The condition is characterised by truncal shortening, extensive hemivertebrae and rib anomalies including malalignment, fusion and reduction in number. Mutations in the Notch signalling pathway genes DLL3, MESP2, LFNG, HES7 and TBX6 have been associated with this defect. In this study, spondylocostal dysostosis in an outbred family of miniature schnauzer dogs is described. Computed tomography demonstrated that the condition mirrors the skeletal defects observed in human cases, but unlike most human cases, the affected dogs were stillborn or died shortly after birth. Through gene mapping and whole genome sequencing, we identified a single-base deletion in the coding region of HES7. The frameshift mutation causes loss of functional domains essential for the oscillatory transcriptional autorepression of HES7 during somitogenesis. A restriction fragment length polymorphism test was applied within the immediate family and supported a highly penetrant autosomal recessive mode of inheritance. The mutation was not observed in wider testing of 117 randomly sampled adult miniature schnauzer and six adult standard schnauzer dogs; providing a significance of association of Praw = 4.759e-36 (genome-wide significant). Despite this apparently low frequency in the Australian population, the allele may be globally distributed based on its presence in two unrelated sires from geographically distant locations. While isolated hemivertebrae have been observed in a small number of other dog breeds, this is the first clinical and genetic diagnosis of spontaneously occurring spondylocostal dysostosis in a non-human mammal and offers an excellent model in which to study this devastating human disorder. The genetic test can be utilized by dog breeders to select away from the disease and avoid unnecessary neonatal losses. PMID:25659135

  20. A familial case of congenital hypothyroidism caused by a homozygous mutation of the thyrotropin receptor gene.

    PubMed

    Bretones, P; Duprez, L; Parma, J; David, M; Vassart, G; Rodien, P

    2001-10-01

    Most of the time congenital hypothyroidism appears as a sporadic disease. In addition to the rare defects in hormonosynthesis associated with goiters, the causes of congenital hypothyroidism include agenesis and ectopy of the thyroid gland. The study of some familial cases has allowed the identification of a few genes responsible for congenital hypothyroidism. We report here a familial case of congenital hypothyroidism, transmitted as a recessive trait, and caused by a homozygous mutation in the thyrotropin receptor (TSH-R). The initial diagnosis of thyroid agenesis, based on the absence of tracer uptake on scintiscan, was incorrect, because ultrasound examination identified severely hypoplastic thyroid tissue in the cervical region. PMID:11716047

  1. Manifestation of diffuse yellowish keratoderma on the palms and soles in autosomal recessive congenital ichthyosis patients may be indicative of mutations in NIPAL4.

    PubMed

    Alavi, Afagh; Shahshahani, Mostafa M; Klotzle, Brandy; Fan, Jian-Bing; Ronaghi, Mostafa; Elahi, Elahe

    2012-04-01

    Ichthyosis is a heterogeneous disorder characterized by abnormal skin scaling over the whole body. Autosomal recessive congenital ichthyosis (ARCI) comprises various forms, the most important of which are lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE). Seven genes have been identified to be causative of ARCI, and these account for disease in 60-80% of the patients. There is notable phenotypic overlap between the major forms of ARCI, and a strong genotype-phenotype correlation has not been found. Here, we initially aimed to identify the causative gene in a large Iranian ARCI pedigree, and subsequently performed genetic analysis on four other affected pedigrees. A genotype-phenotype correlation was sought. Whole genome homozygosity mapping using high-density single nucleotide polymorphism chips was performed on the large pedigree. Linkage to chromosome 5 and a mutation in NIPAL4 causing p.G297R were identified. The same mutation was also identified in two of the remaining four Iranian pedigrees. Two of the NIPAL4 mutation bearing pedigrees were classified as CIE and one as LI. Notably, all NIPAL4 mutation-bearing patients manifested diffuse yellowish keratoderma on the palms and soles. We provide evidence suggesting presentation of this diffuse yellowish keratoderma may be indicative of mutations in NIPAL4, providing an easily assessable genotype-phenotype correlation. PMID:22098531

  2. Autosomal recessive sudden unexpected death in children probably caused by a cardiomyopathy associated with myopathy.

    PubMed Central

    Fried, K; Beer, S; Vure, E; Algom, M; Shapira, Y

    1979-01-01

    The propositus, who died suddenly at the age of 22 months, was investigated because of an unusual myopathy. Family history revealed two sisters and four cousins who had also died suddenly and unexpectedly. The finding of asymmetric septal hypertrophy by echocardiography in the propositus suggested that the cause of the sudden death in the relatives was an undetected cardiomyopathy accompanying a mild and often subclinical myopathy. The affected children were in two sibships and both sets of parents were first cousins. The mother of one sibship was the sister of the father of the other. It is suggested that a gene causes a mild autosomal recessive myopathy with cardiomyopathy that is often undiagnosed and usually ends in sudden unexpected death in the second year of life. The same gene may manifest on echocardiogram in some heterozygotes as asymmetric septal hypertrophy. Images PMID:513079

  3. Homozygous truncating PTPRF mutation causes athelia.

    PubMed

    Borck, Guntram; de Vries, Liat; Wu, Hsin-Jung; Smirin-Yosef, Pola; Nürnberg, Gudrun; Lagovsky, Irina; Ishida, Luis Henrique; Thierry, Patrick; Wieczorek, Dagmar; Nürnberg, Peter; Foley, John; Kubisch, Christian; Basel-Vanagaite, Lina

    2014-08-01

    Athelia is a very rare entity that is defined by the absence of the nipple-areola complex. It can affect either sex and is mostly part of syndromes including other congenital or ectodermal anomalies, such as limb-mammary syndrome, scalp-ear-nipple syndrome, or ectodermal dysplasias. Here, we report on three children from two branches of an extended consanguineous Israeli Arab family, a girl and two boys, who presented with a spectrum of nipple anomalies ranging from unilateral hypothelia to bilateral athelia but no other consistently associated anomalies except a characteristic eyebrow shape. Using homozygosity mapping after single nucleotide polymorphism (SNP) array genotyping and candidate gene sequencing we identified a homozygous frameshift mutation in PTPRF as the likely cause of nipple anomalies in this family. PTPRF encodes a receptor-type protein phosphatase that localizes to adherens junctions and may be involved in the regulation of epithelial cell-cell contacts, peptide growth factor signaling, and the canonical Wnt pathway. Together with previous reports on female mutant Ptprf mice, which have a lactation defect, and disruption of one allele of PTPRF by a balanced translocation in a woman with amastia, our results indicate a key role for PTPRF in the development of the nipple-areola region. PMID:24781087

  4. 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

  5. Mutational diversity and hot spots in the alpha-sarcoglycan gene in autosomal recessive muscular dystrophy (LGMD2D).

    PubMed Central

    Carrié, A; Piccolo, F; Leturcq, F; de Toma, C; Azibi, K; Beldjord, C; Vallat, J M; Merlini, L; Voit, T; Sewry, C; Urtizberea, J A; Romero, N; Tomé, F M; Fardeau, M; Sunada, Y; Campbell, K P; Kaplan, J C; Jeanpierre, M

    1997-01-01

    Sarcoglycanopathies are a genetically heterogeneous group of autosomal recessive muscular dystrophies in which the primary defect may reside in any of the genes coding for the different partners of the sarcolemmal sarcoglycan (SG) complex: the alpha-SG (LGMD2D at 17q21.2), the beta-SG (LGMD2E at 4q12), the gamma-SG (LGMD2C at 13q12), and the delta-SG (LGMD2F at 5q33). We report a series of 20 new unrelated families with 14 different mutations in the alpha-SG gene. Along with the mutations that we previously reported this brings our cohort of patients with alpha-sarcoglycanopathy to a total of 31 unrelated patients, carrying 25 different mutations. The missense mutations reside in the extracellular domain of the protein. Five of 15 missense mutations, carried by unrelated subjects on different haplotype backgrounds and of widespread geographical origins, account for 58% of the mutated chromosomes, with a striking prevalence of the R77C substitution (32%). The severity of the disease varies strikingly and correlates at least in part with the amount of residual protein and the type of mutation. The recurrent R284C substitution is associated with a benign disease course. Images PMID:9192266

  6. CYP17A1 intron mutation causing cryptic splicing in 17α-hydroxylase deficiency.

    PubMed

    Hwang, Daw-Yang; Hung, Chi-Chih; Riepe, Felix G; Auchus, Richard J; Kulle, Alexandra E; Holterhus, Paul-Martin; Chao, Mei-Chyn; Kuo, Mei-Chuan; Hwang, Shang-Jyh; Chen, Hung-Chun

    2011-01-01

    17α-Hydroxylase/17, 20-lyase deficiency (17OHD) is an autosomal recessive disease causing congenital adrenal hyperplasia and a rare cause of hypertension with hypokalemia. The CYP17A1 gene mutation leads to 17OHD and its clinical features. We described an 18 y/o female with clinical features of 17α-hydroxylase/17, 20-lyase deficiency and characterized the functional consequences of an intronic CYP17A1 mutation. The coding regions and flanking intronic bases of the CYP17A1 gene were amplified by PCR and sequenced. The patient is a compound heterozygote for the previously described p.R358X and IVS1 +2T>C mutations. A first intron splice donor site mutation was re-created in minigene and full-length expression vectors. Pre-mRNA splicing of the variant CYP17A1 intron was studied in transfected cells and in a transformed lymphoblastoid cell line. When the full-length CYP17A1 gene and minigene containing the intronic mutation was expressed in transfected cells, the majority (>90%) of mRNA transcripts were incorrectly spliced. Only the p.R358X transcript was detected in the EBV-transformed lymphoblastoid cell line. The IVS1 +2T>C mutation abolished most 17α-hydroxylase/17, 20-lyase enzyme activity by aberrant mRNA splicing to an intronic pseudo-exon, causing a frame shift and early termination. PMID:21966534

  7. CYP17A1 Intron Mutation Causing Cryptic Splicing in 17α-Hydroxylase Deficiency

    PubMed Central

    Hwang, Daw-Yang; Hung, Chi-Chih; Riepe, Felix G.; Auchus, Richard J.; Kulle, Alexandra E.; Holterhus, Paul-Martin; Chao, Mei-Chyn; Kuo, Mei-Chuan; Hwang, Shang-Jyh; Chen, Hung-Chun

    2011-01-01

    17α-hydroxylase/17, 20-lyase deficiency (17OHD) is an autosomal recessive disease causing congenital adrenal hyperplasia and a rare cause of hypertension with hypokalemia. The CYP17A1 gene mutation leads to 17OHD and its clinical features. We described an 18 y/o female with clinical features of 17α-hydroxylase/17, 20-lyase deficiency and characterized the functional consequences of an intronic CYP17A1 mutation. The coding regions and flanking intronic bases of the CYP17A1 gene were amplified by PCR and sequenced. The patient is a compound heterozygote for the previously described p.R358X and IVS1 +2T>C mutations. A first intron splice donor site mutation was re-created in minigene and full-length expression vectors. Pre-mRNA splicing of the variant CYP17A1 intron was studied in transfected cells and in a transformed lymphoblastoid cell line. When the full-length CYP17A1 gene and minigene containing the intronic mutation was expressed in transfected cells, the majority (>90%) of mRNA transcripts were incorrectly spliced. Only the p.R358X transcript was detected in the EBV-transformed lymphoblastoid cell line. The IVS1 +2T>C mutation abolished most 17α-hydroxylase/17, 20-lyase enzyme activity by aberrant mRNA splicing to an intronic pseudo-exon, causing a frame shift and early termination. PMID:21966534

  8. 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

  9. 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

  10. Heterozygous Loss-of-Function Mutations in DLL4 Cause Adams-Oliver Syndrome

    PubMed Central

    Meester, Josephina A.N.; Southgate, Laura; Stittrich, Anna-Barbara; Venselaar, Hanka; Beekmans, Sander J.A.; den Hollander, Nicolette; Bijlsma, Emilia K.; Helderman-van den Enden, Appolonia; Verheij, Joke B.G.M.; Glusman, Gustavo; Roach, Jared C.; Lehman, Anna; Patel, Millan S.; de Vries, Bert B.A.; Ruivenkamp, Claudia; Itin, Peter; Prescott, Katrina; Clarke, Sheila; Trembath, Richard; Zenker, Martin; Sukalo, Maja; Van Laer, Lut; Loeys, Bart; Wuyts, Wim

    2015-01-01

    Adams-Oliver syndrome (AOS) is a rare developmental disorder characterized by the presence of aplasia cutis congenita (ACC) of the scalp vertex and terminal limb-reduction defects. Cardiovascular anomalies are also frequently observed. Mutations in five genes have been identified as a cause for AOS prior to this report. Mutations in EOGT and DOCK6 cause autosomal-recessive AOS, whereas mutations in ARHGAP31, RBPJ, and NOTCH1 lead to autosomal-dominant AOS. Because RBPJ, NOTCH1, and EOGT are involved in NOTCH signaling, we hypothesized that mutations in other genes involved in this pathway might also be implicated in AOS pathogenesis. Using a candidate-gene-based approach, we prioritized DLL4, a critical NOTCH ligand, due to its essential role in vascular development in the context of cardiovascular features in AOS-affected individuals. Targeted resequencing of the DLL4 gene with a custom enrichment panel in 89 independent families resulted in the identification of seven mutations. A defect in DLL4 was also detected in two families via whole-exome or genome sequencing. In total, nine heterozygous mutations in DLL4 were identified, including two nonsense and seven missense variants, the latter encompassing four mutations that replace or create cysteine residues, which are most likely critical for maintaining structural integrity of the protein. Affected individuals with DLL4 mutations present with variable clinical expression with no emerging genotype-phenotype correlations. Our findings demonstrate that DLL4 mutations are an additional cause of autosomal-dominant AOS or isolated ACC and provide further evidence for a key role of NOTCH signaling in the etiology of this disorder. PMID:26299364

  11. c.376G>A mutation in WFS1 gene causes Wolfram syndrome without deafness.

    PubMed

    Safarpour Lima, Behnam; Ghaedi, Hamid; Daftarian, Narsis; Ahmadieh, Hamid; Jamshidi, Javad; Khorrami, Mehdi; Noroozi, Rezvan; Sohrabifar, Nasim; Assarzadegan, Farhad; Hesami, Omid; Taghavi, Shaghayegh; Ahmadifard, Azadeh; Atakhorrami, Minoo; Rahimi-Aliabadi, Simin; Shahmohammadibeni, Neda; Alehabib, Elham; Andarva, Monavvar; Darvish, Hossein; Emamalizadeh, Babak

    2016-02-01

    Wolfram syndrome is one of the rare autosomal recessive, progressive, neurodegenerative disorders, characterized by diabetes mellitus and optic atrophy. Several other features are observed in patients including deafness, ataxia, and peripheral neuropathy. A gene called WFS1 is identified on chromosome 4p, responsible for Wolfram syndrome. We investigated a family consisted of parents and 8 children, which 5 of them have been diagnosed for Wolfram syndrome. WFS1 gene in all family members was sequenced for causative mutations. A mutation (c.376G>A, p.A126T) was found in all affected members in homozygous state and in both parents in heterozygous state. The bioinformatics analysis showed the deleterious effects of this nucleotide change on the structure and function of the protein product. As all of the patients in the family showed the homozygote mutation, and parents were both heterozygote, this mutation is probably the cause of the disease. We identified this mutation in homozygous state for the first time as Wolfram syndrome causation. We also showed that this mutation probably doesn't cause deafness in affected individuals. PMID:26773575

  12. Congenital Hereditary Endothelial Dystrophy Caused by SLC4A11 Mutations Progresses to Harboyan Syndrome

    PubMed Central

    Siddiqui, Salina; Zenteno, Juan Carlos; Rice, Aine; Chacón-Camacho, Oscar; Naylor, Steven G.; Rivera-de la Parra, David; Spokes, David M.; James, Nigel; Toomes, Carmel; Inglehearn, Chris F.

    2013-01-01

    Purpose: Homozygous mutations in SLC4A11 cause 2 rare recessive conditions: congenital hereditary endothelial dystrophy (CHED), affecting the cornea alone, and Harboyan syndrome consisting of corneal dystrophy and sensorineural hearing loss. In addition, adult-onset Fuchs endothelial corneal dystrophy (FECD) is associated with dominant mutations in SLC4A11. In this report, we investigate whether patients with CHED go on to develop hearing loss and whether their parents, who are carriers of an SLC4A11 mutation, show signs of having FECD. Methods: Patients with CHED were screened for mutations in the SLC4A11 gene and underwent audiometric testing. The patients and their parents underwent a clinical examination and specular microscopy. Results: Molecular analyses confirmed SLC4A11 mutations in 4 affected individuals from 3 families. All the patients were found to have varying degrees of sensorineural hearing loss at a higher frequency range. Guttate lesions were seen in 2 of the 4 parents who were available for examination. Conclusions: Our observations suggest that CHED caused by homozygous SLC4A11 mutations progresses to Harboyan syndrome, but the severity of this may vary considerably. Patients with CHED should therefore be monitored for progressive hearing loss. We could not determine conclusively whether the parents of the patients with CHED were at increased risk of developing late-onset FECD. PMID:24351571

  13. A single origin for the most frequent mutation causing late infantile metachromatic leucodystrophy.

    PubMed

    Zlotogora, J; Furman-Shaharabani, Y; Harris, A; Barth, M L; von Figura, K; Gieselmann, V

    1994-09-01

    Metachromatic leucodystrophy is an autosomal recessive degenerative disease of the nervous system caused by the deficiency of the lysosomal enzyme arylsulphatase A (ARSA). We report here on the high incidence of late infantile MLD among Muslim Arabs originating from Jerusalem, most probably because of a founder effect. All the patients were found to be homozygous for 459 + 1 G-->A, a mutation which destroys the splice donor site of exon 2 of the ARSA gene. This mutation has been reported to be the most common mutation causing MLD. We studied the ARSA haplotype defined by three intragenic polymorphic sites in DNA samples from Muslim Arab patients from Jerusalem, a Christian Arab patient originating from the region, and eight other white patients, all homozygous for the 459 + 1 G-->A mutation. All the alleles carried the same haplotype which is in complete linkage disequilibrium with the mutation. This finding indicates a common origin for the 459 + 1 G-->A mutation which may have been introduced into Jerusalem at the time of the Crusades. PMID:7815434

  14. 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

  15. KIF1A missense mutations in SPG30, an autosomal recessive spastic paraplegia: distinct phenotypes according to the nature of the mutations

    PubMed Central

    Klebe, Stephan; Lossos, Alexander; Azzedine, Hamid; Mundwiller, Emeline; Sheffer, Ruth; Gaussen, Marion; Marelli, Cecilia; Nawara, Magdalena; Carpentier, Wassila; Meyer, Vincent; Rastetter, Agnès; Martin, Elodie; Bouteiller, Delphine; Orlando, Laurent; Gyapay, Gabor; El-Hachimi, Khalid H; Zimmerman, Batel; Gamliel, Moriya; Misk, Adel; Lerer, Israela; Brice, Alexis; Durr, Alexandra; Stevanin, Giovanni

    2012-01-01

    The hereditary spastic paraplegias (HSPs) are a clinically and genetically heterogeneous group of neurodegenerative diseases characterised by progressive spasticity in the lower limbs. The nosology of autosomal recessive forms is complex as most mapped loci have been identified in only one or a few families and account for only a small percentage of patients. We used next-generation sequencing focused on the SPG30 chromosomal region on chromosome 2q37.3 in two patients from the original linked family. In addition, wide genome scan and candidate gene analysis were performed in a second family of Palestinian origin. We identified a single homozygous mutation, p.R350G, that was found to cosegregate with the disease in the SPG30 kindred and was absent in 970 control chromosomes while affecting a strongly conserved amino acid at the end of the motor domain of KIF1A. Homozygosity and linkage mapping followed by mutation screening of KIF1A allowed us to identify a second mutation, p.A255V, in the second family. Comparison of the clinical features with the nature of the mutations of all reported KIF1A families, including those reported recently with hereditary sensory and autonomic neuropathy, suggests phenotype–genotype correlations that may help to understand the mechanisms involved in motor neuron degeneration. We have shown that mutations in the KIF1A gene are responsible for SPG30 in two autosomal recessive HSP families. In published families, the nature of the KIF1A mutations seems to be of good predictor of the underlying phenotype and vice versa. PMID:22258533

  16. Null Mutations in LTBP2 Cause Primary Congenital Glaucoma

    PubMed Central

    Ali, Manir; McKibbin, Martin; Booth, Adam; Parry, David A.; Jain, Payal; Riazuddin, S. Amer; Hejtmancik, J. Fielding; Khan, Shaheen N.; Firasat, Sabika; Shires, Mike; Gilmour, David F.; Towns, Katherine; Murphy, Anna-Louise; Azmanov, Dimitar; Tournev, Ivailo; Cherninkova, Sylvia; Jafri, Hussain; Raashid, Yasmin; Toomes, Carmel; Craig, Jamie; Mackey, David A.; Kalaydjieva, Luba; Riazuddin, Sheikh; Inglehearn, Chris F.

    2009-01-01

    Primary congenital glaucoma (PCG) is an autosomal-recessive condition characterized by high intraocular pressure (IOP), usually within the first year of life, which potentially could lead to optic nerve damage, globe enlargement, and permanent loss of vision. To date, PCG has been linked to three loci: 2p21 (GLC3A), for which the responsible gene is CYP1B1, and 1p36 (GLC3B) and 14q24 (GLC3C), for which the genes remain to be identified. Here we report that null mutations in LTBP2 cause PCG in four consanguineous families from Pakistan and in patients of Gypsy ethnicity. LTBP2 maps to chromosome 14q24.3 but is around 1.3 Mb proximal to the documented GLC3C locus. Therefore, it remains to be determined whether LTBP2 is the GLC3C gene or whether a second adjacent gene is also implicated in PCG. LTBP2 is the largest member of the latent transforming growth factor (TGF)-beta binding protein family, which are extracellular matrix proteins with multidomain structure. It has homology to fibrillins and may have roles in cell adhesion and as a structural component of microfibrils. We confirmed localization of LTBP2 in the anterior segment of the eye, at the ciliary body, and particularly the ciliary process. These findings reveal that LTBP2 is essential for normal development of the anterior chamber of the eye, where it may have a structural role in maintaining ciliary muscle tone. PMID:19361779

  17. 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

  18. Founder Fukutin mutation causes Walker-Warburg syndrome in four Ashkenazi Jewish families†

    PubMed Central

    Chang, Wendy; Winder, Thomas L.; LeDuc, Charles A.; Simpson, Lynn L.; Millar, William S.; Dungan, Jeffrey; Ginsberg, Norman; Plaga, Stacey; Moore, Steven A.; Chung, Wendy K.

    2009-01-01

    Objective Walker-Warburg syndrome (WWS) is a genetically heterogeneous congenital muscular dystrophy caused by abnormal glycosylation of α-dystroglycan (α-DG) that is associated with brain malformations and eye anomalies. The Fukutin (FKTN) gene, which causes autosomal recessively inherited WWS is most often associated with Fukuyama congenital muscular dystrophy in Japan. We describe the clinical features of four nonconsanguinous Ashkenazi Jewish families with WWS and identify the underlying genetic basis for WWS. Method We screened for mutations in POMGnT1, POMT1, POMT2, and FKTN, genes causing WWS, by dideoxy sequence analysis. Results We identified an identical homozygous c.1167insA mutation in the FKTN gene on a common haplotype in all four families and identified 2/299 (0.7%) carriers for the c.1167insA mutation among normal American Ashkenazi Jewish adults. Conclusion These data suggest that the c.1167insA FKTN mutation described by us is a founder mutation that can be used to target diagnostic testing and carrier screening in the Ashkenazi Jewish population. PMID:19266496

  19. BRF1 mutations alter RNA polymerase III-dependent transcription and cause neurodevelopmental anomalies.

    PubMed

    Borck, Guntram; Hög, Friederike; Dentici, Maria Lisa; Tan, Perciliz L; Sowada, Nadine; Medeira, Ana; Gueneau, Lucie; Thiele, Holger; Kousi, Maria; Lepri, Francesca; Wenzeck, Larissa; Blumenthal, Ian; Radicioni, Antonio; Schwarzenberg, Tito Livio; Mandriani, Barbara; Fischetto, Rita; Morris-Rosendahl, Deborah J; Altmüller, Janine; Reymond, Alexandre; Nürnberg, Peter; Merla, Giuseppe; Dallapiccola, Bruno; Katsanis, Nicholas; Cramer, Patrick; Kubisch, Christian

    2015-02-01

    RNA polymerase III (Pol III) synthesizes tRNAs and other small noncoding RNAs to regulate protein synthesis. Dysregulation of Pol III transcription has been linked to cancer, and germline mutations in genes encoding Pol III subunits or tRNA processing factors cause neurogenetic disorders in humans, such as hypomyelinating leukodystrophies and pontocerebellar hypoplasia. Here we describe an autosomal recessive disorder characterized by cerebellar hypoplasia and intellectual disability, as well as facial dysmorphic features, short stature, microcephaly, and dental anomalies. Whole-exome sequencing revealed biallelic missense alterations of BRF1 in three families. In support of the pathogenic potential of the discovered alleles, suppression or CRISPR-mediated deletion of brf1 in zebrafish embryos recapitulated key neurodevelopmental phenotypes; in vivo complementation showed all four candidate mutations to be pathogenic in an apparent isoform-specific context. BRF1 associates with BDP1 and TBP to form the transcription factor IIIB (TFIIIB), which recruits Pol III to target genes. We show that disease-causing mutations reduce Brf1 occupancy at tRNA target genes in Saccharomyces cerevisiae and impair cell growth. Moreover, BRF1 mutations reduce Pol III-related transcription activity in vitro. Taken together, our data show that BRF1 mutations that reduce protein activity cause neurodevelopmental anomalies, suggesting that BRF1-mediated Pol III transcription is required for normal cerebellar and cognitive development. PMID:25561519

  20. BRF1 mutations alter RNA polymerase III–dependent transcription and cause neurodevelopmental anomalies

    PubMed Central

    Hög, Friederike; Dentici, Maria Lisa; Tan, Perciliz L.; Sowada, Nadine; Medeira, Ana; Gueneau, Lucie; Thiele, Holger; Kousi, Maria; Lepri, Francesca; Wenzeck, Larissa; Blumenthal, Ian; Radicioni, Antonio; Schwarzenberg, Tito Livio; Mandriani, Barbara; Fischetto, Rita; Morris-Rosendahl, Deborah J.; Altmüller, Janine; Reymond, Alexandre; Nürnberg, Peter; Merla, Giuseppe; Dallapiccola, Bruno; Katsanis, Nicholas; Cramer, Patrick; Kubisch, Christian

    2015-01-01

    RNA polymerase III (Pol III) synthesizes tRNAs and other small noncoding RNAs to regulate protein synthesis. Dysregulation of Pol III transcription has been linked to cancer, and germline mutations in genes encoding Pol III subunits or tRNA processing factors cause neurogenetic disorders in humans, such as hypomyelinating leukodystrophies and pontocerebellar hypoplasia. Here we describe an autosomal recessive disorder characterized by cerebellar hypoplasia and intellectual disability, as well as facial dysmorphic features, short stature, microcephaly, and dental anomalies. Whole-exome sequencing revealed biallelic missense alterations of BRF1 in three families. In support of the pathogenic potential of the discovered alleles, suppression or CRISPR-mediated deletion of brf1 in zebrafish embryos recapitulated key neurodevelopmental phenotypes; in vivo complementation showed all four candidate mutations to be pathogenic in an apparent isoform-specific context. BRF1 associates with BDP1 and TBP to form the transcription factor IIIB (TFIIIB), which recruits Pol III to target genes. We show that disease-causing mutations reduce Brf1 occupancy at tRNA target genes in Saccharomyces cerevisiae and impair cell growth. Moreover, BRF1 mutations reduce Pol III–related transcription activity in vitro. Taken together, our data show that BRF1 mutations that reduce protein activity cause neurodevelopmental anomalies, suggesting that BRF1-mediated Pol III transcription is required for normal cerebellar and cognitive development. PMID:25561519

  1. The swaying mouse as a model of osteogenesis imperfecta caused by WNT1 mutations.

    PubMed

    Joeng, Kyu Sang; Lee, Yi-Chien; Jiang, Ming-Ming; Bertin, Terry K; Chen, Yuqing; Abraham, Annie M; Ding, Hao; Bi, Xiaohong; Ambrose, Catherine G; Lee, Brendan H

    2014-08-01

    Osteogenesis imperfecta (OI) is a heritable disorder of connective tissue characterized by bone fragility and low bone mass. Recently, our group and others reported that WNT1 recessive mutations cause OI, whereas WNT1 heterozygous mutations cause early onset osteoporosis. These findings support the hypothesis that WNT1 is an important WNT ligand regulating bone formation and bone homeostasis. While these studies provided strong human genetic and in vitro functional data, an in vivo animal model to study the mechanism of WNT1 function in bone is lacking. Here, we show that Swaying (Wnt1(sw/sw)) mice previously reported to carry a spontaneous mutation in Wnt1 share major features of OI including propensity to fractures and severe osteopenia. In addition, biomechanical and biochemical analyses showed that Wnt1(sw/sw) mice exhibit reduced bone strength with altered levels of mineral and collagen in the bone matrix that is also distinct from the type I collagen-related form of OI. Further histomorphometric analyses and gene expression studies demonstrate that the bone phenotype is associated with defects in osteoblast activity and function. Our study thus provides in vivo evidence that WNT1 mutations contribute to bone fragility in OI patients and demonstrates that the Wnt1(sw/sw) mouse is a murine model of OI caused by WNT1 mutations. PMID:24634143

  2. The swaying mouse as a model of osteogenesis imperfecta caused by WNT1 mutations

    PubMed Central

    Joeng, Kyu Sang; Lee, Yi-Chien; Jiang, Ming-Ming; Bertin, Terry K.; Chen, Yuqing; Abraham, Annie M.; Ding, Hao; Bi, Xiaohong; Ambrose, Catherine G.; Lee, Brendan H.

    2014-01-01

    Osteogenesis imperfecta (OI) is a heritable disorder of connective tissue characterized by bone fragility and low bone mass. Recently, our group and others reported that WNT1 recessive mutations cause OI, whereas WNT1 heterozygous mutations cause early onset osteoporosis. These findings support the hypothesis that WNT1 is an important WNT ligand regulating bone formation and bone homeostasis. While these studies provided strong human genetic and in vitro functional data, an in vivo animal model to study the mechanism of WNT1 function in bone is lacking. Here, we show that Swaying (Wnt1sw/sw) mice previously reported to carry a spontaneous mutation in Wnt1 share major features of OI including propensity to fractures and severe osteopenia. In addition, biomechanical and biochemical analyses showed that Wnt1sw/sw mice exhibit reduced bone strength with altered levels of mineral and collagen in the bone matrix that is also distinct from the type I collagen-related form of OI. Further histomorphometric analyses and gene expression studies demonstrate that the bone phenotype is associated with defects in osteoblast activity and function. Our study thus provides in vivo evidence that WNT1 mutations contribute to bone fragility in OI patients and demonstrates that the Wnt1sw/sw mouse is a murine model of OI caused by WNT1 mutations. PMID:24634143

  3. 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

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

    PubMed

    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

  6. 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. PMID:25166907

  7. 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

  8. 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

  9. 8-oxoguanine causes spontaneous de novo germline mutations in mice

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

  10. 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

  11. 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

  12. 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

  13. Dihydropyridine receptor mutations cause hypokalemic periodic paralysis

    SciTech Connect

    Ptacek, L.J.; Leppert, M.F.; Tawil, R.

    1994-09-01

    Hypokalemic periodic paralysis (hypoKPP) is an autosomal dominant skeletal muscle disorder manifested by episodic weakness associated with low serum potassium. Genetic linkage analysis has localized the hypoKPP gene to chromosome 1q31-q32 near a dihydropyridine receptor (DHP) gene. This receptor functions as a voltage-gated calcium channel and is also critical for excitation-contraction coupling in a voltage-sensitive and calcium-independent manner. We have characterized patient-specific DHP receptor mutations in 11 probands of 33 independent hypoKPP kindreds that occur at one of two adjacent nucleotides within the same codon and predict substitution of a highly conserved arginine in the S4 segment of domain 4 with either histidine or glycine. In one kindred, the mutation arose de novo. Taken together, these data establish the DHP receptor as the hypoKPP gene. We are unaware of any other human diseases presently known to result from DHP receptor mutations.

  14. 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

  15. 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

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

    PubMed

    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

  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. Inactivating Mutations in ESCO2 Cause SC Phocomelia and Roberts Syndrome: No Phenotype-Genotype Correlation

    PubMed Central

    Schüle, Birgitt; Oviedo, Angelica; Johnston, Kathreen; Pai, Shashidhar; Francke, Uta

    2005-01-01

    The rare, autosomal recessive Roberts syndrome (RBS) is characterized by tetraphocomelia, profound growth deficiency of prenatal onset, craniofacial anomalies, microcephaly, and mental deficiency. SC phocomelia (SC) has a milder phenotype, with a lesser degree of limb reduction and with survival to adulthood. Since heterochromatin repulsion (HR) is characteristic for both disorders and is not complemented in somatic-cell hybrids, it has been hypothesized that the disorders are allelic. Recently, mutations in ESCO2 (establishment of cohesion 1 homolog 2) on 8p21.1 have been reported in RBS. To determine whether ESCO2 mutations are also responsible for SC, we studied three families with SC and two families in which variable degrees of limb and craniofacial abnormalities, detected by fetal ultrasound, led to pregnancy terminations. All cases were positive for HR. We identified seven novel mutations in exons 3–8 of ESCO2. In two families, affected individuals were homozygous—for a 5-nucleotide deletion in one family and a splice-site mutation in the other. In three nonconsanguineous families, probands were compound heterozygous for a single-nucleotide insertion or deletion, a nonsense mutation, or a splice-site mutation. Abnormal splice products were characterized at the RNA level. Since only protein-truncating mutations were identified, regardless of clinical severity, we conclude that genotype does not predict phenotype. Having established that RBS and SC are caused by mutations in the same gene, we delineated the clinical phenotype of the tetraphocomelia spectrum that is associated with HR and ESCO2 mutations and differentiated it from other types of phocomelia that are negative for HR. PMID:16380922

  19. 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

  20. HAX1 Mutations causing SCN and Neurological Disease Lead to Microstructural Abnormalities Revealed by Quantitative MRI

    PubMed Central

    Boztug, Kaan; Ding, Xiao-Qi; Hartmann, Hans; Ziesenitz, Lena; Schäffer, Alejandro A.; Diestelhorst, Jana; Pfeifer, Dietmar; Appaswamy, Giridharan; Kehbel, Sonja; Simon, Thorsten; Jefri, Abdullah Al; Lanfermann, Heinrich; Klein, Christoph

    2011-01-01

    Biallelic mutations in the gene encoding HCLS-associated protein X-1 (HAX1) cause autosomal recessive severe congenital neutropenia. Some of these patients display neurological abnormalities including developmental delay, cognitive impairment and/or epilepsy. Recent genotype-phenotype studies have shown that mutations in HAX1 affecting transcripts A (NM_006118.3) and B (NM_001018837.1) cause the phenotype of SCN with neurological impairment, while mutations affecting isoform A but not B lead to SCN without neurological aberrations. In this study, we identified a consanguineous family with two patients suffering from SCN and neurological disease caused by a novel, homozygous genomic deletion including exons 4–7 of the HAX1 gene. Quantitative MRI analyses revealed general alterations in cerebral proton density in both of the patients, as well as in an additional unrelated patient with another HAX1 mutation (Arg86X) known to be associated with neurological manifestations. This study provides first in vivo evidence of general neurodegeneration associated with HAX1 deficiency in SCN patients. PMID:21108402

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

    PubMed Central

    Alqwaifly, Mohammed; Bohlega, Saeed

    2016-01-01

    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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. Recurrent nonsense mutations within the type VII collagen gene in patients with severe recessive dystrophic epidermolysis bullosa

    SciTech Connect

    Hovnanian, A.; Hilal, L.; Goossens, M. ); Blanchet-Bardon, C.; Prost, Y. de ); Christiano, A.M.; Uitto, J. )

    1994-08-01

    The generalized mutilating form of recessive dystrophic epidermolysis bullosa (i.e., the Hallopeau-Siemens type; HS-RDEB) is a life-threatening disease characterized by extreme mucocutaneous fragility associated with absent or markedly altered anchoring fibrils (AF). Recently, the authors reported linkage between HS-RDEB and the type VII collagen gene (COL7A1), which encodes the major component of AF. In this study, they investigated 52 unrelated HS-RDEB patients and 2 patients with RDEB inversa for the presence, at CpG dinucleotides, of mutations changing CGA arginine codons to premature stop codons TGA within the COL7A1 gene. Eight exons containing 10 CGA codons located in the amino-terminal domain of the COL7A1 gene were studied. Mutation analysis was performed using denaturing gradient gel electrophoresis of PCR-amplified genomic fragments. Direct sequencing of PCR-amplified products with altered electrophoretic mobility led to the characterization of three premature stop codons, each in a single COL7A1 allele, in four patients. Two patients (one affected with HS-RDEB and the other with RDEB inversa) have the same C-to-T transition at arginine codon 109. Two other HS-RDEB patients have a C-to-T transition at arginine 1213 and 1216, respectively. These nonsense mutations predict the truncation of [approximately]56%-92% of the polypeptide, including the collagenous and the noncollagenous NC-2 domains. On the basis of linkage analysis, which showed no evidence for locus heterogeneity in RDEB, it is expected that these patients are compound heterozygotes and have additional mutations on the other COL7A1 allele, leading to impaired AF formation. These results indicate that stop mutations within the COL7A1 gene can underlie both HS-RDEB and RDEB inversa, thus providing further evidence for the implication of this gene in RDEB. 46 refs., 3 figs., 1 tab.

  8. Whole-Exome Sequencing Identifies Mutations in GPR179 Leading to Autosomal-Recessive Complete Congenital Stationary Night Blindness

    PubMed Central

    Audo, Isabelle; Bujakowska, Kinga; Orhan, Elise; Poloschek, Charlotte M.; Defoort-Dhellemmes, Sabine; Drumare, Isabelle; Kohl, Susanne; Luu, Tien D.; Lecompte, Odile; Zrenner, Eberhart; Lancelot, Marie-Elise; Antonio, Aline; Germain, Aurore; Michiels, Christelle; Audier, Claire; Letexier, Mélanie; Saraiva, Jean-Paul; Leroy, Bart P.; Munier, Francis L.; Mohand-Saïd, Saddek; Lorenz, Birgit; Friedburg, Christoph; Preising, Markus; Kellner, Ulrich; Renner, Agnes B.; Moskova-Doumanova, Veselina; Berger, Wolfgang; Wissinger, Bernd; Hamel, Christian P.; Schorderet, Daniel F.; De Baere, Elfride; Sharon, Dror; Banin, Eyal; Jacobson, Samuel G.; Bonneau, Dominique; Zanlonghi, Xavier; Le Meur, Guylene; Casteels, Ingele; Koenekoop, Robert; Long, Vernon W.; Meire, Francoise; Prescott, Katrina; de Ravel, Thomy; Simmons, Ian; Nguyen, Hoan; Dollfus, Hélène; Poch, Olivier; Léveillard, Thierry; Nguyen-Ba-Charvet, Kim; Sahel, José-Alain; Bhattacharya, Shomi S.; Zeitz, Christina

    2012-01-01

    Congenital stationary night blindness (CSNB) is a heterogeneous retinal disorder characterized by visual impairment under low light conditions. This disorder is due to a signal transmission defect from rod photoreceptors to adjacent bipolar cells in the retina. Two forms can be distinguished clinically, complete CSNB (cCSNB) or incomplete CSNB; the two forms are distinguished on the basis of the affected signaling pathway. Mutations in NYX, GRM6, and TRPM1, expressed in the outer plexiform layer (OPL) lead to disruption of the ON-bipolar cell response and have been seen in patients with cCSNB. Whole-exome sequencing in cCSNB patients lacking mutations in the known genes led to the identification of a homozygous missense mutation (c.1807C>T [p.His603Tyr]) in one consanguineous autosomal-recessive cCSNB family and a homozygous frameshift mutation in GPR179 (c.278delC [p.Pro93Glnfs∗57]) in a simplex male cCSNB patient. Additional screening with Sanger sequencing of 40 patients identified three other cCSNB patients harboring additional allelic mutations in GPR179. Although, immunhistological studies revealed Gpr179 in the OPL in wild-type mouse retina, Gpr179 did not colocalize with specific ON-bipolar markers. Interestingly, Gpr179 was highly concentrated in horizontal cells and Müller cell endfeet. The involvement of these cells in cCSNB and the specific function of GPR179 remain to be elucidated. PMID:22325361

  9. 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. PMID:25843205

  10. 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

  11. 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

  12. Mutations in C5ORF42 Cause Joubert Syndrome in the French Canadian Population

    PubMed Central

    Srour, Myriam; Schwartzentruber, Jeremy; Hamdan, Fadi F.; Ospina, Luis H.; Patry, Lysanne; Labuda, Damian; Massicotte, Christine; Dobrzeniecka, Sylvia; Capo-Chichi, José-Mario; Papillon-Cavanagh, Simon; Samuels, Mark E.; Boycott, Kym M.; Shevell, Michael I.; Laframboise, Rachel; Désilets, Valérie; Maranda, Bruno; Rouleau, Guy A.; Majewski, Jacek; Michaud, Jacques L.

    2012-01-01

    Joubert syndrome (JBTS) is an autosomal-recessive disorder characterized by a distinctive mid-hindbrain malformation, developmental delay with hypotonia, ocular-motor apraxia, and breathing abnormalities. Although JBTS was first described more than 40 years ago in French Canadian siblings, the causal mutations have not yet been identified in this family nor in most French Canadian individuals subsequently described. We ascertained a cluster of 16 JBTS-affected individuals from 11 families living in the Lower St. Lawrence region. SNP genotyping excluded the presence of a common homozygous mutation that would explain the clustering of these individuals. Exome sequencing performed on 15 subjects showed that nine affected individuals from seven families (including the original JBTS family) carried rare compound-heterozygous mutations in C5ORF42. Two missense variants (c.4006C>T [p.Arg1336Trp] and c.4690G>A [p.Ala1564Thr]) and a splicing mutation (c.7400+1G>A), which causes exon skipping, were found in multiple subjects that were not known to be related, whereas three other truncating mutations (c.6407del [p.Pro2136Hisfs∗31], c.4804C>T [p.Arg1602∗], and c.7477C>T [p.Arg2493∗]) were identified in single individuals. None of the unaffected first-degree relatives were compound heterozygous for these mutations. Moreover, none of the six putative mutations were detected among 477 French Canadian controls. Our data suggest that mutations in C5ORF42 explain a large portion of French Canadian individuals with JBTS. PMID:22425360

  13. 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

  14. 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

  15. 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

  16. ISPD gene mutations are a common cause of congenital and limb-girdle muscular dystrophies

    PubMed Central

    Cirak, Sebahattin; Foley, Aileen Reghan; Herrmann, Ralf; Willer, Tobias; Yau, Shu; Stevens, Elizabeth; Torelli, Silvia; Brodd, Lina; Kamynina, Alisa; Vondracek, Petr; Roper, Helen; Longman, Cheryl; Korinthenberg, Rudolf; Marrosu, Gianni; Nürnberg, Peter; Michele, Daniel E.; Plagnol, Vincent; Hurles, Matt; Moore, Steven A.; Sewry, Caroline A.; Campbell, Kevin P.; Voit, Thomas

    2013-01-01

    Dystroglycanopathies are a clinically and genetically diverse group of recessively inherited conditions ranging from the most severe of the congenital muscular dystrophies, Walker–Warburg syndrome, to mild forms of adult-onset limb-girdle muscular dystrophy. Their hallmark is a reduction in the functional glycosylation of α-dystroglycan, which can be detected in muscle biopsies. An important part of this glycosylation is a unique O-mannosylation, essential for the interaction of α-dystroglycan with extracellular matrix proteins such as laminin-α2. Mutations in eight genes coding for proteins in the glycosylation pathway are responsible for ∼50% of dystroglycanopathy cases. Despite multiple efforts using traditional positional cloning, the causative genes for unsolved dystroglycanopathy cases have escaped discovery for several years. In a recent collaborative study, we discovered that loss-of-function recessive mutations in a novel gene, called isoprenoid synthase domain containing (ISPD), are a relatively common cause of Walker–Warburg syndrome. In this article, we report the involvement of the ISPD gene in milder dystroglycanopathy phenotypes ranging from congenital muscular dystrophy to limb-girdle muscular dystrophy and identified allelic ISPD variants in nine cases belonging to seven families. In two ambulant cases, there was evidence of structural brain involvement, whereas in seven, the clinical manifestation was restricted to a dystrophic skeletal muscle phenotype. Although the function of ISPD in mammals is not yet known, mutations in this gene clearly lead to a reduction in the functional glycosylation of α-dystroglycan, which not only causes the severe Walker–Warburg syndrome but is also a common cause of the milder forms of dystroglycanopathy. PMID:23288328

  17. 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

  18. 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

  19. 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.

  20. 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.

  1. 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

  2. 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

  3. 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

  4. Development of low-density oligonucleotide microarrays for detecting mutations causing Wilson's disease

    PubMed Central

    Mathur, Manjula; Singh, Ekta; Poduval, T.B.; Rao, Akkipeddi V.S.S.N.

    2015-01-01

    Background & objectives: Wilson's disease (WD) is an autosomal recessive disorder caused by mutations in ATP7B, a copper transporter gene, leading to hepatic and neuropsychiatric manifestations due to copper accumulation. If diagnosed early, WD patients can be managed by medicines reducing morbidity and mortality. Diagnosis of this disease requires a combination of tests and at times is inconclusive due to overlap of the symptoms with other disorders. Genetic testing is the preferred alternative in such cases particularly for individuals with a family history. Use of DNA microarray for detecting mutations in ATP7B gene is gaining popularity because of the advantages it offers in terms of throughput and sensitivity. This study attempts to establish the quality analysis procedures for microarray based diagnosis of Wilson's disease. Methods: A home-made microarrayer was used to print oligonucleotide based low-density microarrays for addressing 62 mutations causing Wilson's disease reported from Indian population. Inter- and intra- array comparisons were used to study quality of the arrays. The arrays were validated by using mutant samples generated by site directed mutagenesis. Results: The hybridization reaction were found to be consistent across the surface of a given microarray. Our results have shown that 52 °C post-hybridization wash yields better reproducibility across experiments compared to 42 °C. Our arrays have shown > 80 per cent sensitivity in detecting these 62 mutations. Interpretation & conclusions: The present results demonstrate the design and evaluation of a low-density microarray for the detection of 62 mutations in ATP7B gene, and show that a microarray based approach can be cost-effective for detecting a large number of mutations simultaneously. This study also provides information on some of the important parameters required for microarray based diagnosis of genetic disorders. PMID:25900953

  5. 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

  6. Mutations in the Proenteropeptidase Gene Are the Molecular Cause of Congenital Enteropeptidase Deficiency

    PubMed Central

    Holzinger, Andreas; Maier, Esther M.; Bück, Cornelius; Mayerhofer, Peter U.; Kappler, Matthias; Haworth, James C.; Moroz, Stanley P.; Hadorn, Hans-Beat; Sadler, J. Evan; Roscher, Adelbert A.

    2002-01-01

    Enteropeptidase (enterokinase [E.C.3.4.21.9]) is a serine protease of the intestinal brush border in the proximal small intestine. It activates the pancreatic proenzyme trypsinogen, which, in turn, releases active digestive enzymes from their inactive pancreatic precursors. Congenital enteropeptidase deficiency is a rare recessively inherited disorder leading, in affected infants, to severe failure to thrive. The genomic structure of the proenteropeptidase gene (25 exons, total gene size 88 kb) was characterized in order to perform DNA sequencing in three clinically and biochemically proved patients with congenital enteropeptidase deficiency who were from two families. We found compound heterozygosity for nonsense mutations (S712X/R857X) in two affected siblings and found compound heterozygosity for a nonsense mutation (Q261X) and a frameshift mutation (FsQ902) in the third patient. In accordance with the biochemical findings, all four defective alleles identified are predicted null alleles leading to a gene product not containing the active site of the enzyme. These data provide first evidence that proenteropeptidase-gene mutations are the primary cause of congenital enteropeptidase deficiency. PMID:11719902

  7. 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

  8. A compound heterozygous mutation in HADHB gene causes an axonal Charcot-Marie-tooth disease

    PubMed Central

    2013-01-01

    Background Charcot-Marie-Tooth disease (CMT) is a heterogeneous disorder of the peripheral nervous system. So far, mutations in hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase/enoyl-CoA hydratase (trifunctional protein), beta subunit (HADHB) gene exhibit three distinctive phenotypes: severe neonatal presentation with cardiomyopathy, hepatic form with recurrent hypoketotic hypoglycemia, and later-onset axonal sensory neuropathy with episodic myoglobinuria. Methods To identify the causative and characterize clinical features of a Korean family with motor and sensory neuropathies, whole exome study (WES), histopathologic study of distal sural nerve, and lower limb MRIs were performed. Results WES revealed that a compound heterozygous mutation in HADHB is the causative of the present patients. The patients exhibited an early-onset axonal sensorimotor neuropathy without episodic myoglobinuria, and showed typical clinical and electrophysiological features of CMT including predominant distal muscle weakness and atrophy. Histopathologic findings of sural nerve were compatible with an axonal CMT neuropathy. Furthermore, they didn’t exhibit any other symptoms of the previously reported HADHB patients. Conclusions These data implicate that mutation in HADHB gene can also cause early-onset axonal CMT instead of typical manifestations in mitochondrial trifunctional protein (MTP) deficiency. Therefore, this study is the first report of a new subtype of autosomal recessive axonal CMT by a compound heterozygous mutation in HADHB, and will expand the clinical and genetic spectrum of HADHB. PMID:24314034

  9. Identification of a Novel MYO15A Mutation in a Chinese Family with Autosomal Recessive Nonsyndromic Hearing Loss

    PubMed Central

    Xia, Hong; Huang, Xiangjun; Guo, Yi; Hu, Pengzhi; He, Guangxiang; Deng, Xiong; Xu, Hongbo; Yang, Zhijian; Deng, Hao

    2015-01-01

    Autosomal recessive nonsyndromic hearing loss (ARNSHL) is a genetically heterogeneous sensorineural disorder, generally manifested with prelingual hearing loss and absence of other clinical manifestations. The aim of this study is to identify the pathogenic gene in a four-generation consanguineous Chinese family with ARNSHL. A novel homozygous variant, c.9316dupC (p.H3106Pfs*2), in the myoxin XVa gene (MYO15A) was identified by exome sequencing and Sanger sequencing. The homozygous MYO15A c.9316dupC variant co-segregated with the phenotypes in the ARNSHL family and was absent in two hundred normal controls. The variant was predicted to interfere with the formation of the Myosin XVa-whirlin-Eps8 complex at the tip of stereocilia, which is indispensable for stereocilia elongation. Our data suggest that the homozygous MYO15A c.9316dupC variant might be the pathogenic mutation, and exome sequencing is a powerful molecular diagnostic strategy for ARNSHL, an extremely heterogeneous disorder. Our findings extend the mutation spectrum of the MYO15A gene and have important implications for genetic counseling for the family. PMID:26308726

  10. 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

  11. 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.

  12. Identification of three novel FGF16 mutations in X-linked recessive fusion of the fourth and fifth metacarpals and possible correlation with heart disease

    PubMed Central

    Laurell, Tobias; Nilsson, Daniel; Hofmeister, Wolfgang; Lindstrand, Anna; Ahituv, Nadav; Vandermeer, Julia; Amilon, Anders; Annerén, Göran; Arner, Marianne; Pettersson, Maria; Jäntti, Nina; Rosberg, Hans-Eric; Cattini, Peter A; Nordenskjöld, Agneta; Mäkitie, Outi; Grigelioniene, Giedre; Nordgren, Ann

    2014-01-01

    Nonsense mutations in FGF16 have recently been linked to X-linked recessive hand malformations with fusion between the fourth and the fifth metacarpals and hypoplasia of the fifth digit (MF4; MIM#309630). The purpose of this study was to perform careful clinical phenotyping and to define molecular mechanisms behind X-linked recessive MF4 in three unrelated families. We performed whole-exome sequencing, and identified three novel mutations in FGF16. The functional impact of FGF16 loss was further studied using morpholino-based suppression of fgf16 in zebrafish. In addition, clinical investigations revealed reduced penetrance and variable expressivity of the MF4 phenotype. Cardiac disorders, including myocardial infarction and atrial fibrillation followed the X-linked FGF16 mutated trait in one large family. Our findings establish that a mutation in exon 1, 2 or 3 of FGF16 results in X-linked recessive MF4 and expand the phenotypic spectrum of FGF16 mutations to include a possible correlation with heart disease. PMID:25333065

  13. Identification of three novel FGF16 mutations in X-linked recessive fusion of the fourth and fifth metacarpals and possible correlation with heart disease.

    PubMed

    Laurell, Tobias; Nilsson, Daniel; Hofmeister, Wolfgang; Lindstrand, Anna; Ahituv, Nadav; Vandermeer, Julia; Amilon, Anders; Annerén, Göran; Arner, Marianne; Pettersson, Maria; Jäntti, Nina; Rosberg, Hans-Eric; Cattini, Peter A; Nordenskjöld, Agneta; Mäkitie, Outi; Grigelioniene, Giedre; Nordgren, Ann

    2014-09-01

    Nonsense mutations in FGF16 have recently been linked to X-linked recessive hand malformations with fusion between the fourth and the fifth metacarpals and hypoplasia of the fifth digit (MF4; MIM#309630). The purpose of this study was to perform careful clinical phenotyping and to define molecular mechanisms behind X-linked recessive MF4 in three unrelated families. We performed whole-exome sequencing, and identified three novel mutations in FGF16. The functional impact of FGF16 loss was further studied using morpholino-based suppression of fgf16 in zebrafish. In addition, clinical investigations revealed reduced penetrance and variable expressivity of the MF4 phenotype. Cardiac disorders, including myocardial infarction and atrial fibrillation followed the X-linked FGF16 mutated trait in one large family. Our findings establish that a mutation in exon 1, 2 or 3 of FGF16 results in X-linked recessive MF4 and expand the phenotypic spectrum of FGF16 mutations to include a possible correlation with heart disease. PMID:25333065

  14. Compound heterozygous mutations of the TNXB gene cause primary myopathy.

    PubMed

    Pénisson-Besnier, Isabelle; Allamand, Valérie; Beurrier, Philippe; Martin, Ludovic; Schalkwijk, Joost; van Vlijmen-Willems, Ivonne; Gartioux, Corine; Malfait, Fransiska; Syx, Delfien; Macchi, Laurent; Marcorelles, Pascale; Arbeille, Brigitte; Croué, Anne; De Paepe, Anne; Dubas, Frédéric

    2013-08-01

    Complete deficiency of the extracellular matrix glycoprotein tenascin-X (TNX) leads to recessive forms of Ehlers-Danlos syndrome, clinically characterized by hyperextensible skin, easy bruising and joint hypermobility. Clinical and pathological studies, immunoassay, and molecular analyses were combined to study a patient suffering from progressive muscle weakness. Clinical features included axial and proximal limb muscle weakness, subclinical heart involvement, minimal skin hyperextensibility, no joint abnormalities, and a history of easy bruising. Skeletal muscle biopsy disclosed striking muscle consistency and the abnormal presence of myotendinous junctions in the muscle belly. TNX immunostaining was markedly reduced in muscle and skin, and serum TNX levels were undetectable. Compound heterozygous mutations were identified: a previously reported 30kb deletion and a non-synonymous novel missense mutation in the TNXB gene. This study identifies a TNX-deficient patient presenting with a primary muscle disorder, thus expanding the phenotypic spectrum of TNX-related abnormalities. Biopsy findings provide evidence that TNX deficiency leads to muscle softness and to mislocalization of myotendinous junctions. PMID:23768946

  15. ARC syndrome with high GGT cholestasis caused by VPS33B mutations

    PubMed Central

    Wang, Jian-She; Zhao, Jing; Li, Li-Ting

    2014-01-01

    Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome (OMIM 208085) is an autosomal recessive disorder that is caused by mutations in 2 interacting genes VPS33B and VIPAS39. Mutations in VPS33B gene account for most cases of ARC. As low or normal gamma-glutamyl transpeptidase (GGT) activity has been described in all patients with ARC syndrome identified so far, ARC syndrome is a possible diagnosis for low GGT cholestasis. Here we describe a Chinese patient with neonatal cholestasis and a high GGT level in three consecutive tests. She had other typical manifestations of ARC syndrome, including arthrogryposis multiplex congenita, renal involvement and ichthyosis. Genetic study of the VPS33B gene further confirmed the diagnosis by identification of compound heterozygosity of two known disease-causing mutations, c.403+2T > A and c.1509-1510insG. The mechanism of high GGT in this patient is unclear. Nevertheless, this case indicates that ARC syndrome cannot be excluded from the differential diagnosis of neonatal cholestasis even if high GGT activity is found. PMID:24782640

  16. ARC syndrome with high GGT cholestasis caused by VPS33B mutations.

    PubMed

    Wang, Jian-She; Zhao, Jing; Li, Li-Ting

    2014-04-28

    Arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome (OMIM 208085) is an autosomal recessive disorder that is caused by mutations in 2 interacting genes VPS33B and VIPAS39. Mutations in VPS33B gene account for most cases of ARC. As low or normal gamma-glutamyl transpeptidase (GGT) activity has been described in all patients with ARC syndrome identified so far, ARC syndrome is a possible diagnosis for low GGT cholestasis. Here we describe a Chinese patient with neonatal cholestasis and a high GGT level in three consecutive tests. She had other typical manifestations of ARC syndrome, including arthrogryposis multiplex congenita, renal involvement and ichthyosis. Genetic study of the VPS33B gene further confirmed the diagnosis by identification of compound heterozygosity of two known disease-causing mutations, c.403+2T > A and c.1509-1510insG. The mechanism of high GGT in this patient is unclear. Nevertheless, this case indicates that ARC syndrome cannot be excluded from the differential diagnosis of neonatal cholestasis even if high GGT activity is found. PMID:24782640

  17. Mutations in FBXL4 Cause Mitochondrial Encephalopathy and a Disorder of Mitochondrial DNA Maintenance

    PubMed Central

    Bonnen, Penelope E.; Yarham, John W.; Besse, Arnaud; Wu, Ping; Faqeih, Eissa A.; Al-Asmari, Ali Mohammad; Saleh, Mohammad A.M.; Eyaid, Wafaa; Hadeel, Alrukban; He, Langping; Smith, Frances; Yau, Shu; Simcox, Eve M.; Miwa, Satomi; Donti, Taraka; Abu-Amero, Khaled K.; Wong, Lee-Jun; Craigen, William J.; Graham, Brett H.; Scott, Kenneth L.; McFarland, Robert; Taylor, Robert W.

    2013-01-01

    Nuclear genetic disorders causing mitochondrial DNA (mtDNA) depletion are clinically and genetically heterogeneous, and the molecular etiology remains undiagnosed in the majority of cases. Through whole-exome sequencing, we identified recessive nonsense and splicing mutations in FBXL4 segregating in three unrelated consanguineous kindreds in which affected children present with a fatal encephalopathy, lactic acidosis, and severe mtDNA depletion in muscle. We show that FBXL4 is an F-box protein that colocalizes with mitochondria and that loss-of-function and splice mutations in this protein result in a severe respiratory chain deficiency, loss of mitochondrial membrane potential, and a disturbance of the dynamic mitochondrial network and nucleoid distribution in fibroblasts from affected individuals. Expression of the wild-type FBXL4 transcript in cell lines from two subjects fully rescued the levels of mtDNA copy number, leading to a correction of the mitochondrial biochemical deficit. Together our data demonstrate that mutations in FBXL4 are disease causing and establish FBXL4 as a mitochondrial protein with a possible role in maintaining mtDNA integrity and stability. PMID:23993193

  18. 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

  19. 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

  20. Autosomal recessive chronic granulomatous disease caused by deletion at a dinucleotide repeat

    SciTech Connect

    Casimir, C.M.; Bu-Ghanim, H.N.; Rowe, P.; Segal, A.W. ); Rodaway, A.R.F.; Bentley, D.L. )

    1991-04-01

    Chronic granulomatous disease (CGD) is a rare inherited condition rendering neutrophils incapable of killing invading pathogens. This condition is due to the failure of a multicomponent microbicidal oxidase that normally yields a low-midpoint-potential b cytochrome (cytochrome b{sub 245}). Although defects in the X chromosome-linked cytochrome account for the majority of CGD patients, as many as 30% of CGD cases are due to an autosomal recessive disease. Of these, {gt}90% have been shown to be defective in the synthesis of a 47-kDa cytosolic component of the oxidase. The authors demonstrate here in three unrelated cases of autosomal recessive CGD that the identical underlying molecular lesion is a dinucleotide deletion at a GTGT tandem repeat, corresponding to the acceptor site of the first intron - exon junction. Slippage of the DNA duplex at this site may contribute to the high frequency of defects in this gene.

  1. Hartnup disorder is caused by mutations in the gene encoding the neutral amino acid transporter SLC6A19.

    PubMed

    Seow, Heng F; Bröer, Stefan; Bröer, Angelika; Bailey, Charles G; Potter, Simon J; Cavanaugh, Juleen A; Rasko, John E J

    2004-09-01

    Hartnup disorder (OMIM 234500) is an autosomal recessive abnormality of renal and gastrointestinal neutral amino acid transport noted for its clinical variability. We localized a gene causing Hartnup disorder to chromosome 5p15.33 and cloned a new gene, SLC6A19, in this region. SLC6A19 is a sodium-dependent and chloride-independent neutral amino acid transporter, expressed predominately in kidney and intestine, with properties of system B(0). We identified six mutations in SLC6A19 that cosegregated with disease in the predicted recessive manner, with most affected individuals being compound heterozygotes. The disease-causing mutations that we tested reduced neutral amino acid transport function in vitro. Population frequencies for the most common mutated SLC6A19 alleles are 0.007 for 517G --> A and 0.001 for 718C --> T. Our findings indicate that SLC6A19 is the long-sought gene that is mutated in Hartnup disorder; its identification provides the opportunity to examine the inconsistent multisystemic features of this disorder. PMID:15286788

  2. Hypomorphic mutations in TRNT1 cause retinitis pigmentosa with erythrocytic microcytosis.

    PubMed

    DeLuca, Adam P; Whitmore, S Scott; Barnes, Jenna; Sharma, Tasneem P; Westfall, Trudi A; Scott, C Anthony; Weed, Matthew C; Wiley, Jill S; Wiley, Luke A; Johnston, Rebecca M; Schnieders, Michael J; Lentz, Steven R; Tucker, Budd A; Mullins, Robert F; Scheetz, Todd E; Stone, Edwin M; Slusarski, Diane C

    2016-01-01

    Retinitis pigmentosa (RP) is a highly heterogeneous group of disorders characterized by degeneration of the retinal photoreceptor cells and progressive loss of vision. While hundreds of mutations in more than 100 genes have been reported to cause RP, discovering the causative mutations in many patients remains a significant challenge. Exome sequencing in an individual affected with non-syndromic RP revealed two plausibly disease-causing variants in TRNT1, a gene encoding a nucleotidyltransferase critical for tRNA processing. A total of 727 additional unrelated individuals with molecularly uncharacterized RP were completely screened for TRNT1 coding sequence variants, and a second family was identified with two members who exhibited a phenotype that was remarkably similar to the index patient. Inactivating mutations in TRNT1 have been previously shown to cause a severe congenital syndrome of sideroblastic anemia, B-cell immunodeficiency, recurrent fevers and developmental delay (SIFD). Complete blood counts of all three of our patients revealed red blood cell microcytosis and anisocytosis with only mild anemia. Characterization of TRNT1 in patient-derived cell lines revealed reduced but detectable TRNT1 protein, consistent with partial function. Suppression of trnt1 expression in zebrafish recapitulated several features of the human SIFD syndrome, including anemia and sensory organ defects. When levels of trnt1 were titrated, visual dysfunction was found in the absence of other phenotypes. The visual defects in the trnt1-knockdown zebrafish were ameliorated by the addition of exogenous human TRNT1 RNA. Our findings indicate that hypomorphic TRNT1 mutations can cause a recessive disease that is almost entirely limited to the retina. PMID:26494905

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. Rare recessive loss-of-function methionyl-tRNA synthetase mutations presenting as a multi-organ phenotype

    PubMed Central

    2013-01-01

    Background Methionyl-tRNA synthetase (MARS) catalyzes the ligation of methionine to its cognate transfer RNA and therefore plays an essential role in protein biosynthesis. Methods We used exome sequencing, aminoacylation assays, homology modeling, and immuno-isolation of transfected MARS to identify and characterize mutations in the methionyl-tRNA synthetase gene (MARS) in an infant with an unexplained multi-organ phenotype. Results We identified compound heterozygous mutations (F370L and I523T) in highly conserved regions of MARS. The parents were each heterozygous for one of the mutations. Aminoacylation assays documented that the F370L and I523T MARS mutants had 18 ± 6% and 16 ± 6%, respectively, of wild-type activity. Homology modeling of the human MARS sequence with the structure of E. coli MARS showed that the F370L and I523T mutations are in close proximity to each other, with residue I523 located in the methionine binding pocket. We found that the F370L and I523T mutations did not affect the association of MARS with the multisynthetase complex. Conclusion This infant expands the catalogue of inherited human diseases caused by mutations in aminoacyl-tRNA synthetase genes. PMID:24103465

  9. KCNJ10 gene mutations causing EAST syndrome (epilepsy, ataxia, sensorineural deafness, and tubulopathy) disrupt channel function

    PubMed Central

    Reichold, Markus; Zdebik, Anselm A.; Lieberer, Evelyn; Rapedius, Markus; Schmidt, Katharina; Bandulik, Sascha; Sterner, Christina; Tegtmeier, Ines; Penton, David; Baukrowitz, Thomas; Hulton, Sally-Anne; Witzgall, Ralph; Ben-Zeev, Bruria; Howie, Alexander J.; Kleta, Robert; Bockenhauer, Detlef; Warth, Richard

    2010-01-01

    Mutations of the KCNJ10 (Kir4.1) K+ channel underlie autosomal recessive epilepsy, ataxia, sensorineural deafness, and (a salt-wasting) renal tubulopathy (EAST) syndrome. We investigated the localization of KCNJ10 and the homologous KCNJ16 in kidney and the functional consequences of KCNJ10 mutations found in our patients with EAST syndrome. Kcnj10 and Kcnj16 were found in the basolateral membrane of mouse distal convoluted tubules, connecting tubules, and cortical collecting ducts. In the human kidney, KCNJ10 staining was additionally observed in the basolateral membrane of the cortical thick ascending limb of Henle's loop. EM of distal tubular cells of a patient with EAST syndrome showed reduced basal infoldings in this nephron segment, which likely reflects the morphological consequences of the impaired salt reabsorption capacity. When expressed in CHO and HEK293 cells, the KCNJ10 mutations R65P, G77R, and R175Q caused a marked impairment of channel function. R199X showed complete loss of function. Single-channel analysis revealed a strongly reduced mean open time. Qualitatively similar results were obtained with coexpression of KCNJ10/KCNJ16, suggesting a dominance of KCNJ10 function in native renal KCNJ10/KCNJ16 heteromers. The decrease in the current of R65P and R175Q was mainly caused by a remarkable shift of pH sensitivity to the alkaline range. In summary, EAST mutations of KCNJ10 lead to impaired channel function and structural changes in distal convoluted tubules. Intriguingly, the metabolic alkalosis present in patients carrying the R65P mutation possibly improves residual function of KCNJ10, which shows higher activity at alkaline pH. PMID:20651251

  10. Mutations in B3GALNT2 Cause Congenital Muscular Dystrophy and Hypoglycosylation of α-Dystroglycan

    PubMed Central

    Stevens, Elizabeth; Carss, Keren J.; Cirak, Sebahattin; Foley, A. Reghan; Torelli, Silvia; Willer, Tobias; Tambunan, Dimira E.; Yau, Shu; Brodd, Lina; Sewry, Caroline A.; Feng, Lucy; Haliloglu, Goknur; Orhan, Diclehan; Dobyns, William B.; Enns, Gregory M.; Manning, Melanie; Krause, Amanda; Salih, Mustafa A.; Walsh, Christopher A.; Hurles, Matthew; Campbell, Kevin P.; Manzini, M. Chiara; Stemple, Derek; Lin, Yung-Yao; Muntoni, Francesco

    2013-01-01

    Mutations in several known or putative glycosyltransferases cause glycosylation defects in α-dystroglycan (α-DG), an integral component of the dystrophin glycoprotein complex. The hypoglycosylation reduces the ability of α-DG to bind laminin and other extracellular matrix ligands and is responsible for the pathogenesis of an inherited subset of muscular dystrophies known as the dystroglycanopathies. By exome and Sanger sequencing we identified two individuals affected by a dystroglycanopathy with mutations in β-1,3-N-acetylgalactosaminyltransferase 2 (B3GALNT2). B3GALNT2 transfers N-acetyl galactosamine (GalNAc) in a β-1,3 linkage to N-acetyl glucosamine (GlcNAc). A subsequent study of a separate cohort of individuals identified recessive mutations in four additional cases that were all affected by dystroglycanopathy with structural brain involvement. We show that functional dystroglycan glycosylation was reduced in the fibroblasts and muscle (when available) of these individuals via flow cytometry, immunoblotting, and immunocytochemistry. B3GALNT2 localized to the endoplasmic reticulum, and this localization was perturbed by some of the missense mutations identified. Moreover, knockdown of b3galnt2 in zebrafish recapitulated the human congenital muscular dystrophy phenotype with reduced motility, brain abnormalities, and disordered muscle fibers with evidence of damage to both the myosepta and the sarcolemma. Functional dystroglycan glycosylation was also reduced in the b3galnt2 knockdown zebrafish embryos. Together these results demonstrate a role for B3GALNT2 in the glycosylation of α-DG and show that B3GALNT2 mutations can cause dystroglycanopathy with muscle and brain involvement. PMID:23453667

  11. Functional consequences of transferrin receptor-2 mutations causing hereditary hemochromatosis type 3.

    PubMed

    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

    2015-05-01

    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

  12. 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

  13. Identification and characterization of SMPD1 mutations causing Niemann-Pick types A and B in Spanish Patients

    PubMed Central

    Rodríguez-Pascau, Laura; Gort, Laura; Schuchman, Edward H.; Vilageliu, Lluïsa; Grinberg, Daniel; Chabás, Amparo

    2009-01-01

    Niemann-Pick disease (NPD) types A/B are both caused by a deficiency of lysosomal acid sphingomyelinase and display autosomal recessive inheritance. These two types of the disease were described according to the presence (type A) or absence (type B) of neurological symptoms. We present a molecular analysis of 19 Spanish NPD A/B patients and two from Maghreb. Eight of the patients had type A and 13 had type B NPD. All mutant SMPD1 alleles were identified, including 17 different mutations, 10 of which were novel. The only frequent mutations in the 21 NPD patients were c.1823_1825delGCC (p.R608del) (38%) and c.1445C>A (p.A482E) (9%). Genotype-phenotype correlations were established for most of the mutations and, in particular, the p.R608del-type B association was confirmed. This mutation accounts for 61.5% of the mutant alleles in the type B subgroup of patients. Expression studies performed on six of the identified mutations confirmed them to be disease-causing due to their low enzyme activity. An allele with a mutation affecting a non-canonical donor splice site produced only aberrant mRNAs corresponding to previously reported non-functional SMPD1 minor transcripts. This study is the first exhaustive mutational analysis of Spanish Niemann-Pick A/B disease patients. PMID:19405096

  14. Autosomal recessive mental retardation: homozygosity mapping identifies 27 single linkage intervals, at least 14 novel loci and several mutation hotspots.

    PubMed

    Kuss, Andreas Walter; Garshasbi, Masoud; Kahrizi, Kimia; Tzschach, Andreas; Behjati, Farkhondeh; Darvish, Hossein; Abbasi-Moheb, Lia; Puettmann, Lucia; Zecha, Agnes; Weissmann, Robert; Hu, Hao; Mohseni, Marzieh; Abedini, Seyedeh Sedigheh; Rajab, Anna; Hertzberg, Christoph; Wieczorek, Dagmar; Ullmann, Reinhard; Ghasemi-Firouzabadi, Saghar; Banihashemi, Susan; Arzhangi, Sanaz; Hadavi, Valeh; Bahrami-Monajemi, Gholamreza; Kasiri, Mahboubeh; Falah, Masoumeh; Nikuei, Pooneh; Dehghan, Atefeh; Sobhani, Masoumeh; Jamali, Payman; Ropers, Hans Hilger; Najmabadi, Hossein

    2011-02-01

    Mental retardation (MR) has a worldwide prevalence of around 2% and is a frequent cause of severe disability. Significant excess of MR in the progeny of consanguineous matings as well as functional considerations suggest that autosomal recessive forms of MR (ARMR) must be relatively common. To shed more light on the causes of autosomal recessive MR (ARMR), we have set out in 2003 to perform systematic clinical studies and autozygosity mapping in large consanguineous Iranian families with non-syndromic ARMR (NS-ARMR). As previously reported (Najmabadi et al. in Hum Genet 121:43-48, 2007), this led us to the identification of 12 novel ARMR loci, 8 of which had a significant LOD score (OMIM: MRT5-12). In the meantime, we and others have found causative gene defects in two of these intervals. Moreover, as reported here, tripling the size of our cohort has enabled us to identify 27 additional unrelated families with NS-ARMR and single-linkage intervals; 14 of these define novel loci for non-syndromic ARMR. Altogether, 13 out of 39 single linkage intervals observed in our cohort were found to cluster at 6 different loci on chromosomes, i.e., 1p34, 4q27, 5p15, 9q34, 11p11-q13 and 19q13, respectively. Five of these clusters consist of two significantly overlapping linkage intervals, and on chr 1p34, three single linkage intervals coincide, including the previously described MRT12 locus. The probability for this distribution to be due to chance is only 1.14 × 10(-5), as shown by Monte Carlo simulation. Thus, in contrast to our previous conclusions, these novel data indicate that common molecular causes of NS-ARMR do exist, and in the Iranian population, the most frequent ones may well account for several percent of the patients. These findings will be instrumental in the identification of the underlying genes. PMID:21063731

  15. A connective tissue disorder caused by mutations of the lysyl hydroxylase 3 gene.

    PubMed

    Salo, Antti M; Cox, Helen; Farndon, Peter; Moss, Celia; Grindulis, Helen; Risteli, Maija; Robins, Simon P; Myllylä, Raili

    2008-10-01

    Lysyl hydroxylase 3 (LH3, encoded by PLOD3) is a multifunctional enzyme capable of catalyzing hydroxylation of lysyl residues and O-glycosylation of hydroxylysyl residues producing either monosaccharide (Gal) or disaccharide (Glc-Gal) derivatives, reactions that form part of the many posttranslational modifications required during collagen biosynthesis. Animal studies have confirmed the importance of LH3, particularly in biosynthesis of the highly glycosylated type IV and VI collagens, but to date, the functional significance in vivo of this enzyme in man is predominantly unknown. We report here a human disorder of LH3 presenting as a compound heterozygote with recessive inheritance. One mutation dramatically reduced the sugar-transfer activity of LH3, whereas another abrogated lysyl hydroxylase activity; these changes were accompanied by reduced LH3 protein levels in cells. The disorder has a unique phenotype causing severe morbidity as a result of features that overlap with a number of known collagen disorders. PMID:18834968

  16. A Connective Tissue Disorder Caused by Mutations of the Lysyl Hydroxylase 3 Gene

    PubMed Central

    Salo, Antti M.; Cox, Helen; Farndon, Peter; Moss, Celia; Grindulis, Helen; Risteli, Maija; Robins, Simon P.; Myllylä, Raili

    2008-01-01

    Lysyl hydroxylase 3 (LH3, encoded by PLOD3) is a multifunctional enzyme capable of catalyzing hydroxylation of lysyl residues and O-glycosylation of hydroxylysyl residues producing either monosaccharide (Gal) or disaccharide (Glc-Gal) derivatives, reactions that form part of the many posttranslational modifications required during collagen biosynthesis. Animal studies have confirmed the importance of LH3, particularly in biosynthesis of the highly glycosylated type IV and VI collagens, but to date, the functional significance in vivo of this enzyme in man is predominantly unknown. We report here a human disorder of LH3 presenting as a compound heterozygote with recessive inheritance. One mutation dramatically reduced the sugar-transfer activity of LH3, whereas another abrogated lysyl hydroxylase activity; these changes were accompanied by reduced LH3 protein levels in cells. The disorder has a unique phenotype causing severe morbidity as a result of features that overlap with a number of known collagen disorders. PMID:18834968

  17. Not very funny: how a single mutation causes heritable bradycardia

    PubMed Central

    Buraei, Zafir; Yang, Jian

    2012-01-01

    HCN channels and their modulation by cAMP play a key role in cardiac pacemaking. In this issue of Structure, Xu and colleagues reveal that an arrhythmia-causing mutation of an HCN channel weakens cAMP binding to the channel by altering the local structure of its entry-exit pathway. PMID:23217679

  18. Homozygous MAPT R406W mutation causing FTDP phenotype: A unique instance of a unique mutation.

    PubMed

    Behnam, Mahdiyeh; Ghorbani, Fatemeh; Shin, Jin-Hong; Kim, Dae-Seong; Jang, Hojung; Nouri, Narges; Sedghi, Maryam; Salehi, Mansoor; Ansari, Behnaz; Basiri, Keivan

    2015-10-01

    Frontotemporal dementia is a neurodegenerative disorder among adults. An autosomal-dominantly form of frontotemporal dementia and parkinsonism linked to chromosome 17q21.2 (FTDP-17) was defined in 1996. The MAPT gene is responsible for the major cases of FTDP-17, and tau also has a role in Alzheimer's disease. So far, different FTDP-17 causing mutations have been identified in the MAPT gene. Among different MAPT mutations, the R406W mutation has been reported with a phenotype resembling Alzheimer's disease. Nonetheless, in this study we have identified the first homozygous case of R406W mutation in an Iranian family which shows characteristics of FTDP, just like the other heterozygous mutations of MAPT. This study clearly indicates that homozygous R406W mutation could result in FTDP phenotype. Our family confirms heterogeneity in the clinical phenotype of MAPT mutations; moreover, in the R406W mutation, a dosage effect is likely to contribute to this clinical heterogeneity. PMID:26086902

  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. 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

  1. Molecular basis of telomere syndrome caused by CTC1 mutations

    PubMed Central

    Chen, Liuh-Yow; Majerská, Jana; Lingner, Joachim

    2013-01-01

    Mutations in CTC1 lead to the telomere syndromes Coats Plus and dyskeratosis congenita (DC), but the molecular mechanisms involved remain unknown. CTC1 forms with STN1 and TEN1 a trimeric complex termed CST, which binds ssDNA, promotes telomere DNA synthesis, and inhibits telomerase-mediated telomere elongation. Here we identify CTC1 disease mutations that disrupt CST complex formation, the physical interaction with DNA polymerase α-primase (polα-primase), telomeric ssDNA binding in vitro, accumulation in the nucleus, and/or telomere association in vivo. While having diverse molecular defects, CTC1 mutations commonly lead to the accumulation of internal single-stranded gaps of telomeric DNA, suggesting telomere DNA replication defects as a primary cause of the disease. Strikingly, mutations in CTC1 may also unleash telomerase repression and telomere length control. Hence, the telomere defect initiated by CTC1 mutations is distinct from the telomerase insufficiencies seen in classical forms of telomere syndromes, which cause short telomeres due to reduced maintenance of distal telomeric ends by telomerase. Our analysis provides molecular evidence that CST collaborates with DNA polα-primase to promote faithful telomere DNA replication. PMID:24115768

  2. Mutations in GNAL: A Novel Cause of Craniocervical Dystonia

    PubMed Central

    Kumar, Kishore R.; Lohmann, Katja; Masuho, Ikuo; Miyamoto, Ryosuke; Ferbert, Andreas; Lohnau, Thora; Kasten, Meike; Hagenah, Johann; Brüggemann, Norbert; Graf, Julia; Münchau, Alexander; Kostic, Vladimir S.; Sue, Carolyn M.; Domingo, Aloysius R.; Rosales, Raymond L.; Lee, Lilian V.; Freimann, Karen; Westenberger, Ana; Mukai, Youhei; Kawarai, Toshitaka; Kaji, Ryuji; Klein, Christine; Martemyanov, Kirill A.; Schmidt, Alexander

    2014-01-01

    Importance Mutations in the GNAL gene have recently been shown to cause primary torsion dystonia. The GNAL-encoded protein (Gαolf) is important for dopamine D1 receptor function and odorant signal transduction. We sequenced all 12 exons of GNAL in 461 patients from Germany, Serbia, and Japan, including 318 patients with dystonia (190 with cervical dystonia), 51 with hyposmia and Parkinson disease, and 92 with tardive dyskinesia or acute dystonic reactions. Observations We identified the following two novel heterozygous putative mutations in GNAL: p.Gly213Ser in a German patient and p.Ala353Thr in a Japanese patient. These variants were predicted to be pathogenic in silico, were absent in ethnically matched control individuals, and impaired Gαolf coupling to D1 receptors in a bioluminescence energy transfer (BRET) assay. Two additional variants appeared to be benign because they behaved like wild-type samples in the BRET assay (p.Ala311Thr) or were detected in ethnically matched controls (p.Thr92Ala). Both patients with likely pathogenic mutations had craniocervical dystonia with onset in the fifth decade of life. No pathogenic mutations were detected in the patients with hyposmia and Parkinson disease, tardive dyskinesias, or acute dystonic reactions. Conclusions and Relevance Mutations in GNAL can cause craniocervical dystonia in different ethnicities. The BRET assay may be a useful tool to support the pathogenicity of identified variants in the GNAL gene. PMID:24535567

  3. Mutations in TMEM76* Cause Mucopolysaccharidosis IIIC (Sanfilippo C Syndrome)

    PubMed Central

    Hřebíček, Martin; Mrázová, Lenka; Seyrantepe, Volkan; Durand, Stéphanie; Roslin, Nicole M.; Nosková, Lenka; Hartmannová, Hana; Ivánek, Robert; Čížková, Alena; Poupětová, Helena; Sikora, Jakub; Uřinovská, Jana; Stránecký, Viktor; Zeman, Jiří; Lepage, Pierre; Roquis, David; Verner, Andrei; Ausseil, Jérôme; Beesley, Clare E.; Maire, Irène; Poorthuis, Ben J. H. M.; van de Kamp, Jiddeke; van Diggelen, Otto P.; Wevers, Ron A.; Hudson, Thomas J.; Fujiwara, T. Mary; Majewski, Jacek; Morgan, Kenneth; Kmoch, Stanislav; Pshezhetsky, Alexey V.

    2006-01-01

    Mucopolysaccharidosis IIIC (MPS IIIC, or Sanfilippo C syndrome) is a lysosomal storage disorder caused by the inherited deficiency of the lysosomal membrane enzyme acetyl–coenzyme A:α-glucosaminide N-acetyltransferase (N-acetyltransferase), which leads to impaired degradation of heparan sulfate. We report the narrowing of the candidate region to a 2.6-cM interval between D8S1051 and D8S1831 and the identification of the transmembrane protein 76 gene (TMEM76), which encodes a 73-kDa protein with predicted multiple transmembrane domains and glycosylation sites, as the gene that causes MPS IIIC when it is mutated. Four nonsense mutations, 3 frameshift mutations due to deletions or a duplication, 6 splice-site mutations, and 14 missense mutations were identified among 30 probands with MPS IIIC. Functional expression of human TMEM76 and the mouse ortholog demonstrates that it is the gene that encodes the lysosomal N-acetyltransferase and suggests that this enzyme belongs to a new structural class of proteins that transport the activated acetyl residues across the cell membrane. PMID:17033958

  4. Mutations in KCTD1 Cause Scalp-Ear-Nipple Syndrome

    PubMed Central

    Marneros, Alexander G.; Beck, Anita E.; Turner, Emily H.; McMillin, Margaret J.; Edwards, Matthew J.; Field, Michael; de Macena Sobreira, Nara Lygia; Perez, Ana Beatriz A.; Fortes, Jose A.R.; Lampe, Anne K.; Giovannucci Uzielli, Maria Luisa; Gordon, Christopher T.; Plessis, Ghislaine; Le Merrer, Martine; Amiel, Jeanne; Reichenberger, Ernst; Shively, Kathryn M.; Cerrato, Felecia; Labow, Brian I.; Tabor, Holly K.; Smith, Joshua D.; Shendure, Jay; Nickerson, Deborah A.; Bamshad, Michael J.

    2013-01-01

    Scalp-ear-nipple (SEN) syndrome is a rare, autosomal-dominant disorder characterized by cutis aplasia of the scalp; minor anomalies of the external ears, digits, and nails; and malformations of the breast. We used linkage analysis and exome sequencing of a multiplex family affected by SEN syndrome to identify potassium-channel tetramerization-domain-containing 1 (KCTD1) mutations that cause SEN syndrome. Evaluation of a total of ten families affected by SEN syndrome revealed KCTD1 missense mutations in each family tested. All of the mutations occurred in a KCTD1 region encoding a highly conserved bric-a-brac, tram track, and broad complex (BTB) domain that is required for transcriptional repressor activity. KCTD1 inhibits the transactivation of the transcription factor AP-2α (TFAP2A) via its BTB domain, and mutations in TFAP2A cause cutis aplasia in individuals with branchiooculofacial syndrome (BOFS), suggesting a potential overlap in the pathogenesis of SEN syndrome and BOFS. The identification of KCTD1 mutations in SEN syndrome reveals a role for this BTB-domain-containing transcriptional repressor during ectodermal development. PMID:23541344

  5. 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

  6. A novel homozygous ISPD gene mutation causing phenotype variability in a consanguineous family.

    PubMed

    Baranello, Giovanni; Saredi, Simona; Sansanelli, Serena; Savadori, Paolo; Canioni, Eleonora; Chiapparini, Luisa; Balestri, Paolo; Malandrini, Alessandro; Arnoldi, Maria Teresa; Pantaleoni, Chiara; Morandi, Lucia; Mora, Marina

    2015-01-01

    Within the group of muscular dystrophies, dystroglycanopathies represent an important subgroup of recessively inherited disorders. Their severity varies from the relatively mild forms of adult-onset limb-girdle muscular dystrophy (LGMD), to the severe congenital muscular dystrophies (CMD) with cerebral and ocular involvement. We describe 2 consanguineous children of Pakistani origin, carrying a new homozygous missense mutation c.367G>A (p.Gly123Arg) in the ISPD gene. Mutations in this gene have been recently reported as a common cause of congenital and limb-girdle muscular dystrophy. Patient 1 is an 8-year-old female with an intermediate phenotype between CMD and early LGMD; patient 2 is a 20-month-old male and second cousin of patient 1, showing a CMD phenotype. Cognitive development, brain MRI, eye examination, electrocardiogram and echocardiogram were normal in both patients. To our knowledge, this is the first report on the co-occurrence of both a CMD/early LGMD intermediate phenotype and a CMD within the same family carrying a homozygous ISPD mutation. PMID:25444434

  7. 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

  8. 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

  9. 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. PMID:25182700

  10. 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

  11. 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

  12. Mutations in a new scaffold protein Sans cause deafness in Jackson shaker mice.

    PubMed

    Kikkawa, Yoshiaki; Shitara, Hiroshi; Wakana, Shigeharu; Kohara, Yuki; Takada, Toyoyuki; Okamoto, Mieko; Taya, Choji; Kamiya, Kazusaku; Yoshikawa, Yasuhiro; Tokano, Hisashi; Kitamura, Ken; Shimizu, Kunihiko; Wakabayashi, Yuichi; Shiroishi, Toshihiko; Kominami, Ryo; Yonekawa, Hiromichi

    2003-03-01

    The Jackson shaker (js) mouse carries a recessive mutation causing phenotypes such as deafness, abnormal behavior (circling and/or head-tossing) and degeneration of inner ear neuroepithelia. Two alleles have been identified so far, the original js and js(seal). A contig of three BAC clones was isolated by positional cloning. Two of the clones rescue the js phenotype by BAC transgenesis. Analysis of transcripts in an overlapping region of the two clones revealed a gene encoding a new scaffold-like protein, Sans, that showed mutations in the two js mutants. One was a guanine nucleotide insertion in the original js allele and the other a 7-base insertion in the js(seal) allele. Both insertions are predicted to inactivate the Sans protein by frameshift mutations resulting in a truncated protein lacking the C-terminal SAM domain. Cochlear hair cells in the js mutants show disorganized stereocilia bundles, and Sans were highly expressed in inner and outer hair cells of cochlea. The existence of major motifs, ankyrin repeats and a SAM domain suggests that Sans may have an important role in the development and maintenance of the stereocilia bundles through protein-protein interaction. PMID:12588793

  13. 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

  14. 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

  15. 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.

  16. A deleterious MYH11 mutation causing familial thoracic aortic dissection

    PubMed Central

    Takeda, Norifumi; Morita, Hiroyuki; Fujita, Daishi; Inuzuka, Ryo; Taniguchi, Yuki; Nawata, Kan; Komuro, Issei

    2015-01-01

    The L1264P and R1275L heterozygous mutations of the myosin heavy chain 11 (MYH11) gene, which are on the same allele, have been reported to cause thoracic aortic aneurysms and/or dissections (TAAD) complicated with patent ductus arteriosus (PDA); however, their contributions to the pathogenesis of TAAD/PDA have not been elucidated. Here we report the first familial case of TAAD with only a MYH11 L1264P mutation, in which PDA was not observed, indicating that L1264P, not R1275L, is responsible for TAAD formation. PMID:27081537

  17. Dominant de novo DSP mutations cause erythrokeratodermia-cardiomyopathy syndrome.

    PubMed

    Boyden, Lynn M; Kam, Chen Y; Hernández-Martín, Angela; Zhou, Jing; Craiglow, Brittany G; Sidbury, Robert; Mathes, Erin F; Maguiness, Sheilagh M; Crumrine, Debra A; Williams, Mary L; Hu, Ronghua; Lifton, Richard P; Elias, Peter M; Green, Kathleen J; Choate, Keith A

    2016-01-15

    Disorders of keratinization (DOK) show marked genotypic and phenotypic heterogeneity. In most cases, disease is primarily cutaneous, and further clinical evaluation is therefore rarely pursued. We have identified subjects with a novel DOK featuring erythrokeratodermia and initially-asymptomatic, progressive, potentially fatal cardiomyopathy, a finding not previously associated with erythrokeratodermia. We show that de novo missense mutations clustered tightly within a single spectrin repeat of DSP cause this novel cardio-cutaneous disorder, which we term erythrokeratodermia-cardiomyopathy (EKC) syndrome. We demonstrate that DSP mutations in our EKC syndrome subjects affect localization of desmosomal proteins and connexin 43 in the skin, and result in desmosome aggregation, widening of intercellular spaces, and lipid secretory defects. DSP encodes desmoplakin, a primary component of desmosomes, intercellular adhesion junctions most abundant in the epidermis and heart. Though mutations in DSP are known to cause other disorders, our cohort features the unique clinical finding of severe whole-body erythrokeratodermia, with distinct effects on localization of desmosomal proteins and connexin 43. These findings add a severe, previously undescribed syndrome featuring erythrokeratodermia and cardiomyopathy to the spectrum of disease caused by mutation in DSP, and identify a specific region of the protein critical to the pathobiology of EKC syndrome and to DSP function in the heart and skin. PMID:26604139

  18. 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

  19. 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

  20. 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

  1. 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

  2. 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

  3. DVL1 Frameshift Mutations Clustering in the Penultimate Exon Cause Autosomal-Dominant Robinow Syndrome

    PubMed Central

    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.

    2015-01-01

    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

  4. 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

  5. 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

  6. 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

  7. Mutations in the GlyT2 Gene (SLC6A5) Are a Second Major Cause of Startle Disease*

    PubMed Central

    Carta, Eloisa; Chung, Seo-Kyung; James, Victoria M.; Robinson, Angela; Gill, Jennifer L.; Remy, Nathalie; Vanbellinghen, Jean-François; Drew, Cheney J. G.; Cagdas, Sophie; Cameron, Duncan; Cowan, Frances M.; Del Toro, Mireria; Graham, Gail E.; Manzur, Adnan Y.; Masri, Amira; Rivera, Serge; Scalais, Emmanuel; Shiang, Rita; Sinclair, Kate; Stuart, Catriona A.; Tijssen, Marina A. J.; Wise, Grahame; Zuberi, Sameer M.; Harvey, Kirsten; Pearce, Brian R.; Topf, Maya; Thomas, Rhys H.; Supplisson, Stéphane; Rees, Mark I.; Harvey, Robert J.

    2012-01-01

    Hereditary hyperekplexia or startle disease is characterized by an exaggerated startle response, evoked by tactile or auditory stimuli, leading to hypertonia and apnea episodes. Missense, nonsense, frameshift, splice site mutations, and large deletions in the human glycine receptor α1 subunit gene (GLRA1) are the major known cause of this disorder. However, mutations are also found in the genes encoding the glycine receptor β subunit (GLRB) and the presynaptic Na+/Cl−-dependent glycine transporter GlyT2 (SLC6A5). In this study, systematic DNA sequencing of SLC6A5 in 93 new unrelated human hyperekplexia patients revealed 20 sequence variants in 17 index cases presenting with homozygous or compound heterozygous recessive inheritance. Five apparently unrelated cases had the truncating mutation R439X. Genotype-phenotype analysis revealed a high rate of neonatal apneas and learning difficulties associated with SLC6A5 mutations. From the 20 SLC6A5 sequence variants, we investigated glycine uptake for 16 novel mutations, confirming that all were defective in glycine transport. Although the most common mechanism of disrupting GlyT2 function is protein truncation, new pathogenic mechanisms included splice site mutations and missense mutations affecting residues implicated in Cl− binding, conformational changes mediated by extracellular loop 4, and cation-π interactions. Detailed electrophysiology of mutation A275T revealed that this substitution results in a voltage-sensitive decrease in glycine transport caused by lower Na+ affinity. This study firmly establishes the combination of missense, nonsense, frameshift, and splice site mutations in the GlyT2 gene as the second major cause of startle disease. PMID:22700964

  8. Rapid detection of the ACMG/ACOG-recommended 23 CFTR disease-causing mutations using ion torrent semiconductor sequencing.

    PubMed

    Elliott, Aaron M; Radecki, Joy; Moghis, Bellal; Li, Xiang; Kammesheidt, Anja

    2012-04-01

    Cystic fibrosis (CF) is one of the most frequently diagnosed autosomal-recessive diseases in the Caucasian population. For general-population CF carrier screening, the American College of Medical Genetics (ACMG)/American College of Obstetricians and Gynecologists (ACOG) have recommended a core panel of 23 mutations that will identify 49-98% of carriers, depending on ethnic background. Using a genotyping technology that can rapidly identify disease-causing mutations is important for high-throughput general-population carrier screening, confirming clinical diagnosis, determining treatment options, and prenatal diagnosis. Here, we describe a proof-of-concept study to determine whether the Ion Torrent Personal Genome Machine (PGM) sequencer platform can reliably identify all ACMG/ACOG 23 CF transmembrane conductance regulator (CFTR) mutations. A WT CF specimen along with mutant DNA specimens representing all 23 CFTR mutations were sequenced bidirectionally on the Ion Torrent 314 chip to determine the accuracy of the PGM for CFTR variant detection. We were able to reliably identify all of the targeted mutations except for 2184delA, which lies in a difficult, 7-mer homopolymer tract. Based on our study, we believe PGM sequencing may be a suitable technology for identifying CFTR mutations in the future. However, as a result of the elevated rate of base-calling errors within homopolymer stretches, mutations within such regions currently need to be evaluated carefully using an alternative method. PMID:22468138

  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. 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

  11. 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

  12. Evidence for compound heterozygosity causing mild and severe forms of autosomal recessive spinal muscular atrophy.

    PubMed Central

    Talbot, K; Rodrigues, N; Bernert, G; Bittner, R; Davies, K

    1996-01-01

    Spinal muscular atrophy is an autosomal recessive disease of motor neurone degeneration which shows a variable phenotype. Two candidate genes show deletions in affected subjects but with no distinction between different forms of the disease. We report an unusual family in which mild and severe SMA coexists and patients are deleted for the SMN gene. The father is affected with late onset SMA; therefore this family shows pseudodominant inheritance. When typed using closely linked flanking markers the severely affected son does not share the same haplotype as his sib, who is deleted for SMN but shows no signs yet of SMA. This supports the hypothesis that differences in SMA phenotype can be explained by a multiple allele model. Images PMID:9004135

  13. 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

  14. 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

  15. 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. PMID:25504045

  16. Characterization of 18 new mutations in COL7A1 in recessive dystrophic epidermolysis bullosa provides evidence for distinct molecular mechanisms underlying defective anchoring fibril formation.

    PubMed Central

    Hovnanian, A; Rochat, A; Bodemer, C; Petit, E; Rivers, C A; Prost, C; Fraitag, S; Christiano, A M; Uitto, J; Lathrop, M; Barrandon, Y; de Prost, Y

    1997-01-01

    We have characterized 21 mutations in the type VII collagen gene (COL7A1) encoding the anchoring fibrils, 18 of which were not previously reported, in patients from 15 unrelated families with recessive dystrophic epidermolysis bullosa (RDEB). COL7A1 mutations in both alleles were identified by screening the 118 exons of COL7A1 and flanking intron regions. Fourteen mutations created premature termination codons (PTCs) and consisted of nonsense mutations, small insertions, deletions, and splice-site mutations. A further seven mutations predicted glycine or arginine substitutions in the collagenous domain of the molecule. Two mutations were found in more than one family reported in this study, and six of the seven missense mutations showed clustering within exons 72-74 next to the hinge region of the protein. Patients who were homozygous or compound heterozygotes for mutations leading to PTCs displayed both absence or drastic reduction of COL7A1 transcripts and undetectable type VII collagen protein in skin. In contrast, missense mutations were associated with clearly detectable COL7A1 transcripts and with normal or reduced expression of type VII collagen protein at the dermo/epidermal junction. Our results provide evidence for at least two distinct molecular mechanisms underlying defective anchoring fibril formation in RDEB: one involving PTCs leading to mRNA instability and absence of protein synthesis, the other implicating missense mutations resulting in the synthesis of type VII collagen polypeptide with decreased stability and/or altered function. Genotype-phenotype correlations suggested that the nature and location of these mutations are important determinants of the disease phenotype and showed evidence for interfamilial phenotypic variability. Images Figure 1 Figure 2 Figure 4 Figure 5 Figure 6 PMID:9326325

  17. 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

  18. MUTATIONS IN TTC37 CAUSE TRICHOHEPATOENTERIC SYNDROME (PHENOTYPIC DIARRHOEA OF INFANCY)

    PubMed Central

    Hartley, Jane Louise; Zachos, Nicholas C.; Dawood, Ban; Donowitz, Mark; Forman, Julia; Pollitt, Rodney J; Morgan, Neil V; Tee, Louise; Gissen, Paul; Kahr, Walter H.A.; Knisely, A.S.; Watson, Steve; Chitayat, David; Booth, IW; Protheroe, Sue; Murphy, Stephen; de Vries, Esther; Kelly, Deirdre A; Maher, Eamonn R

    2010-01-01

    Background Trichohepatoenteric syndrome (THES) is an autosomal recessive disorder characterised by life-threatening diarrhoea in infancy, immunodeficiency, liver disease, trichorrhexis nodosa, facial dysmorphism, hypopigmentation and cardiac defects. We attempted to characterise the phenotype and elucidate the molecular basis of THES. Methods Twelve patients with classical THES from 11 families had detailed phenotyping. Autozygosity mapping was undertaken in 8 patients from consanguineous families using 250k single nucleotide polymorphism (SNP) arrays and linked regions evaluated using microsatellite markers. Linkage was confirmed to one region from which candidate genes were analysed. The effect of mutations on protein production and/or localisation in hepatocytes and intestinal epithelial cells from affected patients was characterised by immunohistochemistry. Results Previously unrecognised platelet abnormalities (reduced platelet α-granules, unusual stimulated alpha granule content release, abnormal lipid inclusions, abnormal platelet canalicular system and reduced number of microtubules) were identified. The THES locus was mapped to 5q14.3 – 5q21.2. Sequencing of candidate genes demonstrated mutations in TTC37, which encodes the uncharacterised tetratricopeptide repeat protein, thespin. Bioinformatic analysis suggested thespin to be involved in protein-protein interactions or chaperone. Preliminary studies of enterocyte brush-border ion transporter proteins (NHE2, NHE3, Aquaporin 7, Na/I symporter and H / K ATPase) showed reduced expression or mislocalisation in all THES patients with different profiles for each. In contrast the basolateral localisation of Na/K ATPase was not altered. Conclusion THES is caused by mutations in TTC37. TTC37 mutations have a multisystem effect which may be due to abnormal stability and / or intracellular localisation of TTC37 target proteins. PMID:20176027

  19. 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

  20. Melanism in Peromyscus Is Caused by Independent Mutations in Agouti

    PubMed Central

    Kingsley, Evan P.; Manceau, Marie; Wiley, Christopher D.; Hoekstra, Hopi E.

    2009-01-01

    Identifying the molecular basis of phenotypes that have evolved independently can provide insight into the ways genetic and developmental constraints influence the maintenance of phenotypic diversity. Melanic (darkly pigmented) phenotypes in mammals provide a potent system in which to study the genetic basis of naturally occurring mutant phenotypes because melanism occurs in many mammals, and the mammalian pigmentation pathway is well understood. Spontaneous alleles of a few key pigmentation loci are known to cause melanism in domestic or laboratory populations of mammals, but in natural populations, mutations at one gene, the melanocortin-1 receptor (Mc1r), have been implicated in the vast majority of cases, possibly due to its minimal pleiotropic effects. To investigate whether mutations in this or other genes cause melanism in the wild, we investigated the genetic basis of melanism in the rodent genus Peromyscus, in which melanic mice have been reported in several populations. We focused on two genes known to cause melanism in other taxa, Mc1r and its antagonist, the agouti signaling protein (Agouti). While variation in the Mc1r coding region does not correlate with melanism in any population, in a New Hampshire population, we find that a 125-kb deletion, which includes the upstream regulatory region and exons 1 and 2 of Agouti, results in a loss of Agouti expression and is perfectly associated with melanic color. In a second population from Alaska, we find that a premature stop codon in exon 3 of Agouti is associated with a similar melanic phenotype. These results show that melanism has evolved independently in these populations through mutations in the same gene, and suggest that melanism produced by mutations in genes other than Mc1r may be more common than previously thought. PMID:19649329

  1. Compound heterozygous mutations of TYMP as underlying causes of mitochondrial neurogastrointestinal encephalomyopathy (MNGIE).

    PubMed

    Suh, Bum Chun; Jeong, Ha-Neul; Yoon, Byung Suk; Park, Ji Hoon; Kim, Hye Jin; Park, Sun Wha; Hwang, Jung Hee; Choi, Byung-Ok; Chung, Ki Wha

    2013-07-01

    Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE), an autosomal recessive multiorgan disease, frequently associated with mutations in the thymidine phosphorylase (TYMP) gene. TYMP encodes thymidine phosphorylase (TP), which has an essential role in the nucleotide salvage pathway for mitochondrial DNA (mtDNA) replication. This study reports an MNGIE patient with novel compound heterozygous missense mutations (Thr151Pro and Leu270Pro) in TYMP. Each mutation was inherited from one parent. Neither mutation was found in the controls and the mutation sites were well conserved between different species. Neither large deletion nor causative point mutations were found in the mtDNA. The patient presented with MNGIE symptoms, including gastrointestinal discomfort, external ophthalmoplegia, pigmentary retinopathy and demyelinating type diffuse sensory motor polyneuropathy. The patient demonstrated an early-onset but mild phenotype, with 9.6% TP activity; therefore, patients with these compound heterozygous mutations may exhibit a mild phenotype with a variable onset age according to TP activity level. PMID:23685548

  2. The Polg Mutator Phenotype Does Not Cause Dopaminergic Neurodegeneration in DJ-1-Deficient Mice1,2,3

    PubMed Central

    Hauser, David N.; Primiani, Christopher T.; Langston, Rebekah G.; Kumaran, Ravindran

    2015-01-01

    Abstract 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. PMID:26464968

  3. Two new severe mutations causing guanidinoacetate methyltransferase deficiency.

    PubMed

    Carducci, C; Leuzzi, V; Carducci, C; Prudente, S; Mercuri, L; Antonozzi, I

    2000-12-01

    Primary disorders of creatine metabolism have been only recently described. We report new molecular and biochemical findings obtained from a child affected by guanidinoacetate methyltransferase deficiency. This patient presented with neurological regression, epilepsy, and a movement disorder during the first year of life. HPLC analysis showed high concentrations of guanidinoacetic acid in urine, plasma, and CSF. Molecular analyses of cDNA and genomic DNA revealed two novel mutations, a G insertion following nucleotide 491 of the cDNA (c.491insG) in exon 5 and a transversion at nt -3 in intron 5 (IVS5-3C>G). The c.491insG mutation causes a frameshift and a premature stop codon at the end of the exon. The IVS5-3C>G mutation prevents the splicing of the last exon of the gene precluding the complete maturation of the transcript and, most likely, causes rapid degradation of the mRNA. PMID:11136556

  4. PDE3A mutations cause autosomal dominant hypertension with brachydactyly.

    PubMed

    Maass, Philipp G; Aydin, Atakan; Luft, Friedrich C; Schächterle, Carolin; Weise, Anja; Stricker, Sigmar; Lindschau, Carsten; Vaegler, Martin; Qadri, Fatimunnisa; Toka, Hakan R; Schulz, Herbert; Krawitz, Peter M; Parkhomchuk, Dmitri; Hecht, Jochen; Hollfinger, Irene; Wefeld-Neuenfeld, Yvette; Bartels-Klein, Eireen; Mühl, Astrid; Kann, Martin; Schuster, Herbert; Chitayat, David; Bialer, Martin G; Wienker, Thomas F; Ott, Jürg; Rittscher, Katharina; Liehr, Thomas; Jordan, Jens; Plessis, Ghislaine; Tank, Jens; Mai, Knut; Naraghi, Ramin; Hodge, Russell; Hopp, Maxwell; Hattenbach, Lars O; Busjahn, Andreas; Rauch, Anita; Vandeput, Fabrice; Gong, Maolian; Rüschendorf, Franz; Hübner, Norbert; Haller, Hermann; Mundlos, Stefan; Bilginturan, Nihat; Movsesian, Matthew A; Klussmann, Enno; Toka, Okan; Bähring, Sylvia

    2015-06-01

    Cardiovascular disease is the most common cause of death worldwide, and hypertension is the major risk factor. Mendelian hypertension elucidates mechanisms of blood pressure regulation. Here we report six missense mutations in PDE3A (encoding phosphodiesterase 3A) in six unrelated families with mendelian hypertension and brachydactyly type E (HTNB). The syndrome features brachydactyly type E (BDE), severe salt-independent but age-dependent hypertension, an increased fibroblast growth rate, neurovascular contact at the rostral-ventrolateral medulla, altered baroreflex blood pressure regulation and death from stroke before age 50 years when untreated. In vitro analyses of mesenchymal stem cell-derived vascular smooth muscle cells (VSMCs) and chondrocytes provided insights into molecular pathogenesis. The mutations increased protein kinase A-mediated PDE3A phosphorylation and resulted in gain of function, with increased cAMP-hydrolytic activity and enhanced cell proliferation. Levels of phosphorylated VASP were diminished, and PTHrP levels were dysregulated. We suggest that the identified PDE3A mutations cause the syndrome. VSMC-expressed PDE3A deserves scrutiny as a therapeutic target for the treatment of hypertension. PMID:25961942

  5. Mutation in the cystatin C gene causes hereditary brain hemorrhage.

    PubMed

    Palsdottir, A; Abrahamson, M; Thorsteinsson, L; Arnason, A; Olafsson, I; Grubb, A; Jensson, O

    1989-01-01

    Hereditary cystatin C amyloid angiopathy (HCCAA) is an autosomal dominant disorder leading to massive brain hemorrhage and death in young adults (Jensson et al., 1987). A variant of a potent inhibitor of cysteine proteinases, cystatin C (Barrett et al., 1984), is deposited as amyloid fibrils in the cerebral arteries of the patients (Ghiso et al., 1986). We have used the full length cystatin C cDNA probe (Abrahamson et al., 1987) to demonstrate a mutation in the codon for leucine at position 68, which abolishes an Alu I restriction site in cystatin C gene of the HCCAA patients. The Alu I marker has been used to show that this mutation is transmitted only in the affected members in all eight families investigated, proving that the mutated cystatin C gene causes HCCAA. This DNA marker will be useful for the diagnosis of HCCAA in patients, asymptomatic affected individuals and also for pre-natal diagnosis. HCCAA is the first human disorder known to be caused by an abnormal gene for a cysteine proteinase inhibitor. PMID:2602420

  6. 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

  7. TCTN3 Mutations Cause Mohr-Majewski Syndrome

    PubMed Central

    Thomas, Sophie; Legendre, Marine; Saunier, Sophie; Bessières, Bettina; Alby, Caroline; Bonnière, Maryse; Toutain, Annick; Loeuillet, Laurence; Szymanska, Katarzyna; Jossic, Frédérique; Gaillard, Dominique; Yacoubi, Mohamed Tahar; Mougou-Zerelli, Soumaya; David, Albert; Barthez, Marie-Anne; Ville, Yves; Bole-Feysot, Christine; Nitschke, Patrick; Lyonnet, Stanislas; Munnich, Arnold; Johnson, Colin A.; Encha-Razavi, Férechté; Cormier-Daire, Valérie; Thauvin-Robinet, Christel; Vekemans, Michel; Attié-Bitach, Tania

    2012-01-01

    Orofaciodigital syndromes (OFDSs) consist of a group of heterogeneous disorders characterized by abnormalities in the oral cavity, face, and digits and associated phenotypic abnormalities that lead to the delineation of 13 OFDS subtypes. Here, by a combined approach of homozygozity mapping and exome ciliary sequencing, we identified truncating TCTN3 mutations as the cause of an extreme form of OFD associated with bone dysplasia, tibial defect, cystic kidneys, and brain anomalies (OFD IV, Mohr-Majewski syndrome). Analysis of 184 individuals with various ciliopathies (OFD, Meckel, Joubert, and short rib polydactyly syndromes) led us to identify four additional truncating TCTN3 mutations in unrelated fetal cases with overlapping Meckel and OFD IV syndromes and one homozygous missense mutation in a family with Joubert syndrome. By exploring roles of TCTN3 in human ciliary related functions, we found that TCTN3 is necessary for transduction of the sonic hedgehog (SHH) signaling pathway, as revealed by abnormal processing of GLI3 in patient cells. These results are consistent with the suggested role of its murine ortholog, which forms a complex at the ciliary transition zone with TCTN1 and TCTN2, both of which are also implicated in the transduction of SHH signaling. Overall, our data show the involvement of the transition zone protein TCTN3 in the regulation of the key SHH signaling pathway and that its disruption causes a severe form of ciliopathy, combining features of Meckel and OFD IV syndromes. PMID:22883145

  8. 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

  9. 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

  10. A combined LDL receptor/LDL receptor adaptor protein 1 mutation as the cause for severe familial hypercholesterolemia.

    PubMed

    Soufi, Muhidien; Rust, Stephan; Walter, Michael; Schaefer, Juergen R

    2013-05-25

    Familial hypercholesterolemia (FH) results from impaired catabolism of plasma low density lipoproteins (LDL), thus leading to high cholesterol, atherosclerosis, and a high risk of premature myocardial infarction. FH is commonly caused by defects of the LDL receptor or its main ligand apoB, together mediating cellular uptake and clearance of plasma LDL. In some cases FH is inherited by mutations in the genes of PCSK9 and LDLRAP1 (ARH) in a dominant or recessive trait. The encoded proteins are required for LDL receptor stability and internalization within the LDLR pathway. To detect the underlying genetic defect in a family of Turkish descent showing unregular inheritance of severe FH, we screened the four candidate genes by denaturing gradient gel electrophoresis (DGGE) mutation analysis. We identified different combinatory mixtures of LDLR- and LDLRAP1-gene defects as the cause for severe familial hypercholesterolemia in this family. We also show for the first time that a heterozygous LDLR mutation combined with a homozygous LDLRAP1 mutation produces a more severe hypercholesterolemia phenotype in the same family than a homozygous LDLR mutation alone. PMID:23510778

  11. Maternal uniparental isodisomy and heterodisomy on chromosome 6 encompassing a CUL7 gene mutation causing 3M syndrome.

    PubMed

    Sasaki, K; Okamoto, N; Kosaki, K; Yorifuji, T; Shimokawa, O; Mishima, H; Yoshiura, K-i; Harada, N

    2011-11-01

    We report a case of segmental uniparental maternal hetero- and isodisomy involving the whole of chromosome 6 (mat-hUPD6 and mat-iUPD6) and a cullin 7 (CUL7) gene mutation in a Japanese patient with 3M syndrome. 3M syndrome is a rare autosomal recessive disorder characterized by severe pre- and postnatal growth retardation that was recently reported to involve mutations in the CUL7 or obscurin-like 1 (OBSL1) genes. We encountered a patient with severe growth retardation, an inverted triangular gloomy face, an inverted triangle-shaped head, slender long bones, inguinal hernia, hydrocele testis, mild ventricular enlargement, and mild mental retardation. Sequence analysis of the CUL7 gene of the patient revealed a homozygous missense mutation, c.2975G>C. Genotype analysis using a single nucleotide polymorphism array revealed two mat-hUPD and two mat-iUPD regions involving the whole of chromosome 6 and encompassing CUL7. 3M syndrome caused by complete paternal iUPD of chromosome 6 involving a CUL7 mutation has been reported, but there have been no reports describing 3M syndrome with maternal UPD of chromosome 6. Our results represent a combination of iUPDs and hUPDs from maternal chromosome 6 involving a CUL7 mutation causing 3M syndrome. PMID:21166787

  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. 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

  14. Mutations in LTBP4 Cause a Syndrome of Impaired Pulmonary, Gastrointestinal, Genitourinary, Musculoskeletal, and Dermal Development

    PubMed Central

    Urban, Zsolt; Hucthagowder, Vishwanathan; Schürmann, Nura; Todorovic, Vesna; Zilberberg, Lior; Choi, Jiwon; Sens, Carla; Brown, Chester W.; Clark, Robin D.; Holland, Kristen E.; Marble, Michael; Sakai, Lynn Y.; Dabovic, Branka; Rifkin, Daniel B.; Davis, Elaine C.

    2009-01-01

    We report recessive mutations in the gene for the latent transforming growth factor-β binding protein 4 (LTBP4) in four unrelated patients with a human syndrome disrupting pulmonary, gastrointestinal, urinary, musculoskeletal, craniofacial, and dermal development. All patients had severe respiratory distress, with cystic and atelectatic changes in the lungs complicated by tracheomalacia and diaphragmatic hernia. Three of the four patients died of respiratory failure. Cardiovascular lesions were mild, limited to pulmonary artery stenosis and patent foramen ovale. Gastrointestinal malformations included diverticulosis, enlargement, tortuosity, and stenosis at various levels of the intestinal tract. The urinary tract was affected by diverticulosis and hydronephrosis. Joint laxity and low muscle tone contributed to musculoskeletal problems compounded by postnatal growth delay. Craniofacial features included microretrognathia, flat midface, receding forehead, and wide fontanelles. All patients had cutis laxa. Four of the five identified LTBP4 mutations led to premature termination of translation and destabilization of the LTBP4 mRNA. Impaired synthesis and lack of deposition of LTBP4 into the extracellular matrix (ECM) caused increased transforming growth factor-β (TGF-β) activity in cultured fibroblasts and defective elastic fiber assembly in all tissues affected by the disease. These molecular defects were associated with blocked alveolarization and airway collapse in the lung. Our results show that coupling of TGF-β signaling and ECM assembly is essential for proper development and is achieved in multiple human organ systems by multifunctional proteins such as LTBP4. PMID:19836010

  15. 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.

  16. Loss of function mutation in glutamic pyruvate transaminase 2 (GPT2) causes developmental encephalopathy

    PubMed Central

    Celis, Katrina; Shuldiner, Scott; Haverfield, Eden V.; Cappell, Joshua; Yang, Rongze; Gong, Da-Wei

    2016-01-01

    Intellectual disability is genetically heterogeneous, and it is likely that many of the responsible genes have not yet been identified. We describe three siblings with isolated, severe developmental encephalopathy. After extensive uninformative genetic and metabolic testing, whole exome sequencing identified a homozygous novel variant in glutamic pyruvate transaminase 2 (GPT2) or alanine transaminase 2 (ALT2), c.459 C>G p.Ser153Arg that segregated with developmental encephalopathy in the family. This variant was predicted to be damaging by all in silico prediction algorithms. GPT2 is the gene encoding ALT2 which is responsible for the reversible transamination of alanine and 2-oxoglutarate to form pyruvate and glutamate. GPT2 is expressed in brain and is in the pathway to generate glutamate, an excitatory neurotransmitter. Functional assays of recombinant wild-type and mutant ALT2 proteins demonstrated the p.Ser153Arg mutation resulted in a severe loss of enzymatic function. We suggest that recessively inherited loss of function GPT2 mutations are a novel cause of intellectual disability. PMID:25758935

  17. 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

  18. 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

  19. Neu-Laxova Syndrome, an Inborn Error of Serine Metabolism, Is Caused by Mutations in PHGDH

    PubMed Central

    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.

    2014-01-01

    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

  20. 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

  1. Novel mutation in SLC6A19 causing late-onset seizures in Hartnup disorder.

    PubMed

    Cheon, Chong Kun; Lee, Beom Hee; Ko, Jung Min; Kim, Hyun-Ji; Yoo, Han-Wook

    2010-05-01

    Hartnup disorder is caused by an inborn error of neutral amino acid transport in the kidneys and intestines. It is characterized by pellagra-like rash, ataxia, and psychotic behavior. Elevated urinary neutral amino acids are the first indicator of the disorder. SLC6A19 was identified as the causative gene in autosomal-recessive Hartnup disorder, which encodes the amino acid transporter B(0)AT1, mediating neutral amino acid transport from the luminal compartment to the intracellular space. Here, we report on a Korean boy aged 8 years and 5 months with Hartnup disorder, as confirmed by SLC6A19 gene analysis. He manifested seizures, attention-deficit hyperactivity disorder, and mental retardation without pellagra or ataxia. Multiple neutral amino acids were increased in his urine, and genetic analysis of SLC6A19 revealed compound heterozygous mutations, c.908C>T (p.Ser303Leu) and c.1787_1788insG (p.Thr596fsX73), both of which are novel. A novel SLC6A19 gene mutation was associated with late-onset seizures in a Korean patient with Hartnup disorder. PMID:20399395

  2. 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

  3. 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

  4. 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

  5. Mutational inactivation of STAG2 causes aneuploidy in human cancer.

    PubMed

    Solomon, David A; Kim, Taeyeon; Diaz-Martinez, Laura A; Fair, Joshlean; Elkahloun, Abdel G; Harris, Brent T; Toretsky, Jeffrey A; Rosenberg, Steven A; Shukla, Neerav; Ladanyi, Marc; Samuels, Yardena; James, C David; Yu, Hongtao; Kim, Jung-Sik; Waldman, Todd

    2011-08-19

    Most cancer cells are characterized by aneuploidy, an abnormal number of chromosomes. We have identified a clue to the mechanistic origins of aneuploidy through integrative genomic analyses of human tumors. A diverse range of tumor types were found to harbor deletions or inactivating mutations of STAG2, a gene encoding a subunit of the cohesin complex, which regulates the separation of sister chromatids during cell division. Because STAG2 is on the X chromosome, its inactivation requires only a single mutational event. Studying a near-diploid human cell line with a stable karyotype, we found that targeted inactivation of STAG2 led to chromatid cohesion defects and aneuploidy, whereas in two aneuploid human glioblastoma cell lines, targeted correction of the endogenous mutant alleles of STAG2 led to enhanced chromosomal stability. Thus, genetic disruption of cohesin is a cause of aneuploidy in human cancer. PMID:21852505

  6. Long-term treatment outcome of two patients with pyridoxine-dependent epilepsy caused by ALDH7A1 mutations: normal neurocognitive outcome.