Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Hum Mutat ; 40(11): 2021-2032, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31184401

RESUMO

The X-linked NLGN3 gene, encoding a postsynaptic cell adhesion molecule, was involved in a nonsyndromic monogenic form of autism spectrum disorder (ASD) by the description of one unique missense variant, p.Arg451Cys (Jamain et al. 2003). We investigated here the pathogenicity of additional missense variants identified in two multiplex families with intellectual disability (ID) and ASD: c.1789C>T, p.Arg597Trp, previously reported by our group (Redin et al. 2014) and present in three affected cousins and c.1540C>T, p.Pro514Ser, identified in two affected brothers. Overexpression experiments in HEK293 and HeLa cell lines revealed that both variants affect the level of the mature NLGN3 protein, its localization at the plasma membrane and its presence as a cleaved form in the extracellular environment, even more drastically than what was reported for the initial p.Arg451Cys mutation. The variants also induced an unfolded protein response, probably due to the retention of immature NLGN3 proteins in the endoplasmic reticulum. In comparison, the c.1894A>G, p.Ala632Thr and c.1022T>C, p.Val341Ala variants, present in males from the general population, have no effect. Our report of two missense variants affecting the normal localization of NLGN3 in a total of five affected individuals reinforces the involvement of the NLGN3 gene in a neurodevelopmental disorder characterized by ID and ASD.

2.
Nat Commun ; 10(1): 2129, 2019 05 13.
Artigo em Inglês | MEDLINE | ID: mdl-31086189

RESUMO

De novo heterozygous missense variants in the γ-tubulin gene TUBG1 have been linked to human malformations of cortical development associated with intellectual disability and epilepsy. Here, we investigated through in-utero electroporation and in-vivo studies, how four of these variants affect cortical development. We show that TUBG1 mutants affect neuronal positioning, disrupting the locomotion of new-born neurons but without affecting progenitors' proliferation. We further demonstrate that pathogenic TUBG1 variants are linked to reduced microtubule dynamics but without major structural nor functional centrosome defects in subject-derived fibroblasts. Additionally, we developed a knock-in Tubg1Y92C/+ mouse model and assessed consequences of the mutation. Although centrosomal positioning in bipolar neurons is correct, they fail to initiate locomotion. Furthermore, Tubg1Y92C/+ animals show neuroanatomical and behavioral defects and increased epileptic cortical activity. We show that Tubg1Y92C/+ mice partially mimic the human phenotype and therefore represent a relevant model for further investigations of the physiopathology of cortical malformations.


Assuntos
Malformações do Desenvolvimento Cortical/genética , Microtúbulos/metabolismo , Neurogênese/genética , Neurônios/fisiologia , Tubulina (Proteína)/genética , Animais , Comportamento Animal , Movimento Celular/genética , Centrossomo/metabolismo , Córtex Cerebral/anormalidades , Córtex Cerebral/citologia , Córtex Cerebral/diagnóstico por imagem , Modelos Animais de Doenças , Embrião de Mamíferos , Epilepsia/genética , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Fibroblastos/ultraestrutura , Técnicas de Introdução de Genes , Predisposição Genética para Doença , Células HeLa , Humanos , Microscopia Intravital , Masculino , Camundongos , Camundongos Transgênicos , Microscopia Confocal , Microscopia Eletrônica , Microtúbulos/genética , Mutação de Sentido Incorreto
3.
JAMA Neurol ; 75(10): 1234-1245, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29913018

RESUMO

Importance: Movement disorders are characterized by a marked genotypic and phenotypic heterogeneity, complicating diagnostic work in clinical practice and molecular diagnosis. Objective: To develop and evaluate a targeted sequencing approach using a customized panel of genes involved in movement disorders. Design, Setting and Participants: We selected 127 genes associated with movement disorders to create a customized enrichment in solution capture array. Targeted high-coverage sequencing was applied to DNA samples taken from 378 eligible patients at 1 Luxembourgian, 1 Algerian, and 25 French tertiary movement disorder centers between September 2014 and July 2016. Patients were suspected of having inherited movement disorders because of early onset, family history, and/or complex phenotypes. They were divided in 5 main movement disorder groups: parkinsonism, dystonia, chorea, paroxysmal movement disorder, and myoclonus. To compare approaches, 23 additional patients suspected of having inherited cerebellar ataxia were included, on whom whole-exome sequencing (WES) was done. Data analysis occurred from November 2015 to October 2016. Main Outcomes and Measures: Percentages of individuals with positive diagnosis, variants of unknown significance, and negative cases; mutational frequencies and clinical phenotyping of genes associated with movement disorders. Results: Of the 378 patients (of whom 208 were male [55.0%]), and with a median (range) age at disease onset of 31 (0-84) years, probable pathogenic variants were identified in 83 cases (22.0%): 46 patients with parkinsonism (55% of 83 patients), 21 patients (25.3%) with dystonia, 7 patients (8.4%) with chorea, 7 patients (8.4%) with paroxysmal movement disorders, and 2 patients (2.4%) with myoclonus as the predominant phenotype. Some genes were mutated in several cases in the cohort. Patients with pathogenic variants were significantly younger (median age, 27 years; interquartile range [IQR], 5-36 years]) than the patients without diagnosis (median age, 35 years; IQR, 15-46 years; P = .04). Diagnostic yield was significantly lower in patients with dystonia (21 of 135; 15.6%; P = .03) than in the overall cohort. Unexpected genotype-phenotype correlations in patients with pathogenic variants deviating from the classic phenotype were highlighted, and 49 novel probable pathogenic variants were identified. The WES analysis of the cohort of 23 patients with cerebellar ataxia led to an overall diagnostic yield of 26%, similar to panel analysis but at a cost 6 to 7 times greater. Conclusions and Relevance: High-coverage sequencing panel for the delineation of genes associated with movement disorders was efficient and provided a cost-effective diagnostic alternative to whole-exome and whole-genome sequencing.

4.
Eur J Hum Genet ; 26(4): 527-536, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29422660

RESUMO

Cockayne syndrome is an autosomal recessive multisystem disorder characterized by intellectual disability, microcephaly, severe growth failure, sensory impairment, peripheral neuropathy, and cutaneous sensitivity. This rare disease is linked to disease-causing variations in the ERCC6 (CSB) and ERCC8 (CSA) genes. Various degrees of severity have been described according to age at onset and survival, without any clear genotype-phenotype correlation. All types of nucleotide changes have been observed in CS genes, including splice variations mainly affecting the splice site consensus sequences. We report here the case of two brothers from a consanguineous family presenting a severe but long-term survival phenotype of Cockayne syndrome. We identified in the patients a homozygous deep intronic nucleotide variation causing the insertion of a cryptic exon in the ERCC8 (CSA) transcript, by modifying intronic regulatory elements important for exon definition. The pathogenesis of the nucleotide variant NG_009289.1(NM_000082.3):c.173+1119G>C was validated in vitro with a reporter minigene system. To our knowledge, these are the first Cockayne patients described with this kind of disease-causing variation, though molecular mechanism underlying early onset symptoms and unexpected slow raise of progression of the disease remain to be elucidated.

5.
Hum Mol Genet ; 27(2): 224-238, 2018 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-29077851

RESUMO

Genetic findings reported by our group and others showed that de novo missense variants in the KIF2A gene underlie malformations of brain development called pachygyria and microcephaly. Though KIF2A is known as member of the Kinesin-13 family involved in the regulation of microtubule end dynamics through its ATP dependent MT-depolymerase activity, how KIF2A variants lead to brain malformations is still largely unknown. Using cellular and in utero electroporation approaches, we show here that KIF2A disease-causing variants disrupts projection neuron positioning and interneuron migration, as well as progenitors proliferation. Interestingly, further dissection of this latter process revealed that ciliogenesis regulation is also altered during progenitors cell cycle. Altogether, our data suggest that deregulation of the coupling between ciliogenesis and cell cycle might contribute to the pathogenesis of KIF2A-related brain malformations. They also raise the issue whether ciliogenesis defects are a hallmark of other brain malformations, such as those related to tubulins and MT-motor proteins variants.

6.
Am J Hum Genet ; 101(3): 428-440, 2017 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-28823707

RESUMO

Pontocerebellar hypoplasia (PCH) is a heterogeneous group of rare recessive disorders with prenatal onset, characterized by hypoplasia of pons and cerebellum. Mutations in a small number of genes have been reported to cause PCH, and the vast majority of PCH cases are explained by mutations in TSEN54, which encodes a subunit of the tRNA splicing endonuclease complex. Here we report three families with homozygous truncating mutations in TBC1D23 who display moderate to severe intellectual disability and microcephaly. MRI data from available affected subjects revealed PCH, small normally proportioned cerebellum, and corpus callosum anomalies. Furthermore, through in utero electroporation, we show that downregulation of TBC1D23 affects cortical neuron positioning. TBC1D23 is a member of the Tre2-Bub2-Cdc16 (TBC) domain-containing RAB-specific GTPase-activating proteins (TBC/RABGAPs). Members of this protein family negatively regulate RAB proteins and modulate the signaling between RABs and other small GTPases, some of which have a crucial role in the trafficking of intracellular vesicles and are involved in neurological disorders. Here, we demonstrate that dense core vesicles and lysosomal trafficking dynamics are affected in fibroblasts harboring TBC1D23 mutation. We propose that mutations in TBC1D23 are responsible for a form of PCH with small, normally proportioned cerebellum and should be screened in individuals with syndromic pontocereballar hypoplasia.


Assuntos
Doenças Cerebelares/genética , Cerebelo/anormalidades , Proteínas Ativadoras de GTPase/genética , Homozigoto , Microcefalia/genética , Mutação , Malformações do Sistema Nervoso/genética , Neurônios/patologia , Adolescente , Animais , Células Cultivadas , Doenças Cerebelares/patologia , Cerebelo/patologia , Criança , Pré-Escolar , Deficiências do Desenvolvimento/genética , Deficiências do Desenvolvimento/patologia , Embrião de Mamíferos/metabolismo , Embrião de Mamíferos/patologia , Feminino , Humanos , Deficiência Intelectual/genética , Deficiência Intelectual/patologia , Masculino , Camundongos , Microcefalia/patologia , Malformações do Sistema Nervoso/patologia , Neuroblastoma/genética , Neuroblastoma/patologia , Crescimento Neuronal , Neurônios/metabolismo , Linhagem
7.
Nat Genet ; 48(11): 1349-1358, 2016 11.
Artigo em Inglês | MEDLINE | ID: mdl-27694961

RESUMO

Neurodevelopmental disorders with periventricular nodular heterotopia (PNH) are etiologically heterogeneous, and their genetic causes remain in many cases unknown. Here we show that missense mutations in NEDD4L mapping to the HECT domain of the encoded E3 ubiquitin ligase lead to PNH associated with toe syndactyly, cleft palate and neurodevelopmental delay. Cellular and expression data showed sensitivity of PNH-associated mutants to proteasome degradation. Moreover, an in utero electroporation approach showed that PNH-related mutants and excess wild-type NEDD4L affect neurogenesis, neuronal positioning and terminal translocation. Further investigations, including rapamycin-based experiments, found differential deregulation of pathways involved. Excess wild-type NEDD4L leads to disruption of Dab1 and mTORC1 pathways, while PNH-related mutations are associated with deregulation of mTORC1 and AKT activities. Altogether, these data provide insights into the critical role of NEDD4L in the regulation of mTOR pathways and their contributions in cortical development.


Assuntos
Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Mutação de Sentido Incorreto , Heterotopia Nodular Periventricular/genética , Ubiquitina-Proteína Ligases/genética , Animais , Células Cultivadas , Feminino , Humanos , Masculino , Camundongos , Ubiquitina-Proteína Ligases Nedd4 , Domínios Proteicos/genética , Proteínas Proto-Oncogênicas c-akt/metabolismo , Transdução de Sinais , Serina-Treonina Quinases TOR/metabolismo , Ubiquitina/metabolismo
8.
J Neurol ; 263(7): 1314-22, 2016 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27142713

RESUMO

Establishing a molecular diagnosis of autosomal recessive cerebellar ataxias (ARCA) is challenging due to phenotype and genotype heterogeneity. We report the validation of a previously published clinical practice-based algorithm to diagnose ARCA. Two assessors performed a blind analysis to determine the most probable mutated gene based on comprehensive clinical and paraclinical data, without knowing the molecular diagnosis of 23 patients diagnosed by targeted capture of 57 ataxia genes and high-throughput sequencing coming from a 145 patients series. The correct gene was predicted in 61 and 78 % of the cases by the two assessors, respectively. There was a high inter-rater agreement [K = 0.85 (0.55-0.98) p < 0.001] confirming the algorithm's reproducibility. Phenotyping patients with proper clinical examination, imaging, biochemical investigations and nerve conduction studies remain crucial for the guidance of molecular analysis and to interpret next generation sequencing results. The proposed algorithm should be helpful for diagnosing ARCA in clinical practice.


Assuntos
Algoritmos , Ataxia Cerebelar/diagnóstico , Ataxia Cerebelar/genética , Genes Recessivos/genética , Sequenciamento de Nucleotídeos em Larga Escala , Adolescente , Adulto , Idade de Início , Idoso , Bases de Dados Genéticas , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reprodutibilidade dos Testes , Estudos Retrospectivos , Adulto Jovem
9.
J Neurol ; 263(8): 1552-8, 2016 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-27230853

RESUMO

Peroxisomal biogenesis disorders (PBDs) consist of a heterogeneous group of autosomal recessive diseases, in which peroxisome assembly and proliferation are impaired leading to severe multisystem disease and early death. PBDs include Zellweger spectrum disorders (ZSDs) with a relatively mild clinical phenotype caused by PEX1, (MIM# 602136), PEX2 (MIM# 170993), PEX6 (MIM# 601498), PEX10 (MIM# 602859), PEX12 (MIM# 601758), and PEX16 (MIM# 603360) mutations. Three adult patients are reported belonging to a non-consanguineous French family affected with slowly progressive cerebellar ataxia, axonal neuropathy, and pyramidal signs. Mental retardation and diabetes mellitus were optional. The age at onset was in childhood or in adolescence (3-15 years). Brain MRI showed marked cerebellar atrophy. Biochemical blood analyses suggested a mild peroxisomal defect. With whole exome sequencing, two mutations in PEX10 were found in the three patients: c.827G>T (novel) causing the missense change p.Cys276Phe and c.932G>A causing the missense change p.Arg311Gln. The phenotypic spectrum related to PEX10 mutations includes slowly progressive, syndromic recessive ataxia.


Assuntos
Ataxia Cerebelar/genética , Mutação de Sentido Incorreto/genética , Transtornos Peroxissômicos/genética , Receptores Citoplasmáticos e Nucleares/genética , Encéfalo/diagnóstico por imagem , Análise Mutacional de DNA , Avaliação da Deficiência , Progressão da Doença , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Peroxinas , Transtornos Peroxissômicos/sangue , Transtornos Peroxissômicos/diagnóstico por imagem
10.
Eur J Hum Genet ; 24(8): 1154-9, 2016 08.
Artigo em Inglês | MEDLINE | ID: mdl-26669662

RESUMO

Ataxia is a symptom that is often associated with syndromic inherited diseases. We previously reported the linkage of a novel syndrome, ataxia with blindness and deafness (SCAR3/SCABD, OMIM# 271250), to chromosome 6p21-p23 by linkage mapping of an Arab Israeli consanguineous family. We have now identified by whole-exome sequencing a homozygous missense mutation in the Arab Israeli family in the SLC52A2 gene located in 8qter, therefore excluding linkage of this family to 6p. We confirmed the involvement of SLC52A2 by the identification of a second mutation in an independent family with an identical syndromic presentation, which we suggest to name SCABD2. SCABD2 is therefore allelic to Brown-Vialleto-Van Laere syndrome type 2 defined by prominent motoneuronopathy and deafness, and also caused by SLC52A2 mutations. In the course of this project, we identified a clinically similar family with a homozygous missense mutation in PEX6, which is located in 6p21. Therefore, despite false linkage in the initial family, SCABD1/SCAR3 is located in 6p21 and is caused by PEX6 mutations. Both SLC52A2 and PEX6 should be included in screening panels for the diagnosis of syndromic inherited ataxias, particularly as patients with mutations in SLC52A2 can be ameliorated by riboflavin supplementation.


Assuntos
Adenosina Trifosfatases/genética , Cegueira/genética , Surdez/genética , Mutação de Sentido Incorreto , Receptores Acoplados a Proteínas-G/genética , Ataxias Espinocerebelares/genética , Família de Proteínas da Síndrome de Wiskott-Aldrich/genética , ATPases Associadas a Diversas Atividades Celulares , Adolescente , Adulto , Cegueira/diagnóstico , Células Cultivadas , Criança , Surdez/diagnóstico , Exoma , Feminino , Humanos , Masculino , Linhagem , Ataxias Espinocerebelares/diagnóstico , Síndrome
11.
BMC Med Genet ; 16: 36, 2015 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-26068213

RESUMO

BACKGROUND: Autosomal recessive cerebellar ataxias (ARCA) are a complex group of neurodegenerative disorders with great genetic and phenotypic heterogeneity, over 30 genes/loci have been associated with more than 20 different clinical forms of ARCA. Genetic heterogeneity combined with highly variable clinical expression of the cerebellar symptoms and overlapping features complicate furthermore the etiological diagnosis of ARCA. The determination of the most frequent mutations and corresponding ataxias, as well as particular features specific to a population, are mandatory to facilitate and speed up the diagnosis process, especially when an appropriate treatment is available. METHODS: We explored 166 patients (115 families) refered to the neurology units of Algiers central hospitals (Algeria) with a cerebellar ataxia phenotype segregating as an autosomal recessive pattern of inheritance. Genomic DNA was extracted from peripheral blood samples and mutational screening was performed by PCR and direct sequencing or by targeted genomic capture and massive parallel sequencing of 57 genes associated with inherited cerebellar ataxia phenotypes. RESULTS: In this work we report the clinical and molecular results obtained on a large cohort of Algerian patients (110 patients/76 families) with genetically determined autosomal recessive ataxia, representing 9 different types of ARCA and 23 different mutations, including 6 novel ones. The five most common ARCA in this cohort were Friedreich ataxia, ataxia with isolated vitamin E deficiency, ataxia with oculomotor apraxia type 2, autosomal recessive spastic ataxia of Charlevoix-Saguenay and ataxia with oculomotor apraxia type 1. CONCLUSION: We report here a large cohort of patients with genetically determined autosomal recessive ataxia and the first study of the genetic context of ARCA in Algeria. This study showed that in Algerian patients, the two most common types of ataxia (Friedreich ataxia and ataxia with isolated vitamin E deficiency) coexist with forms that may be less common or underdiagnosed. To refine the genotype/phenotype correlation in rare and heteregeneous diseases as autosomal recessive ataxias, more extensive epidemiological investigations and reports are necessary as well as more accurate and detailed clinical characterizations. The use of standardized clinical and molecular protocols would thus enable a better knowledge of the different forms of ARCA.


Assuntos
Ataxia Cerebelar/genética , Adolescente , Adulto , Argélia/epidemiologia , Ataxia Cerebelar/epidemiologia , Criança , Pré-Escolar , Estudos de Coortes , Feminino , Genômica , Humanos , Lactente , Recém-Nascido , Padrões de Herança , Masculino , Mutação , Fenótipo , Adulto Jovem
12.
Hum Mol Genet ; 24(2): 463-70, 2015 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-25205112

RESUMO

Lichtenstein-Knorr syndrome is an autosomal recessive condition that associates sensorineural hearing loss and cerebellar ataxia. Here, we report the first identification of a gene involved in Lichtenstein-Knorr syndrome. By using a combination of homozygosity mapping and whole-exome sequencing, we identified the homozygous p.Gly305Arg missense mutation in SLC9A1 that segregates with the disease in a large consanguineous family. Mutant glycine 305 is a highly conserved amino acid present in the eighth transmembrane segment of all metazoan orthologues of NHE1, the Na(+)/H(+) exchanger 1, encoded by SLC9A1. We demonstrate that the p.Gly305Arg mutation causes the near complete de-glycosylation, mis-targeting and loss of proton pumping activity of NHE1. The comparison of our family with the phenotypes of spontaneous and knockout Slc9a1 murine models demonstrates that the association between ataxia and hearing loss is caused by complete or near complete loss of function of NHE1 and altered regulation of pHi in the central nervous system.


Assuntos
Proteínas de Transporte de Cátions/genética , Ataxia Cerebelar/genética , Surdez/genética , Displasia Fibrosa Óssea/genética , Síndromes de Imunodeficiência/genética , Mutação de Sentido Incorreto , Neutropenia/genética , Trocadores de Sódio-Hidrogênio/genética , Animais , Proteínas de Transporte de Cátions/metabolismo , Ataxia Cerebelar/metabolismo , Surdez/metabolismo , Facies , Feminino , Displasia Fibrosa Óssea/metabolismo , Humanos , Síndromes de Imunodeficiência/metabolismo , Masculino , Camundongos , Camundongos Knockout , Neutropenia/metabolismo , Trocador 1 de Sódio-Hidrogênio , Trocadores de Sódio-Hidrogênio/metabolismo
13.
JAMA Neurol ; 71(10): 1305-10, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-25089919

RESUMO

IMPORTANCE: ANO10 mutations have been reported to cause a novel form of autosomal recessive cerebellar ataxia (ARCA). Our objective was to report 9 ataxic patients carrying 8 novel ANO10 mutations to improve the delineation of this form of ARCA and provide genotype-phenotype correlation. OBSERVATIONS: The ANO10 gene has been sequenced in 186 consecutive patients with ARCA. The detailed phenotype of patients with ANO10 mutations was investigated and compared with the 12 previously reported cases. The mean age at onset was 33 years (range, 17-43 years), and the disease progression was slow. Corticospinal tract signs were frequent, including extensor plantar reflexes and/or diffuse tendon reflexes and/or spasticity. No patient in our series had peripheral neuropathy. Magnetic resonance imaging of the brains of our patients revealed marked cerebellar atrophy. The most frequent mutation, a mononucleotide expansion from a polyA repeat tract (c.132dupA) that causes protein truncation, was never observed in homozygosity. Only 2 truncating mutations were reported in homozygosity, one of which (c.1150-1151del) was associated with juvenile or adolescent onset and mental retardation, whereas we show that the presence of at least 1 missense or in-frame mutation is associated with adult onset and slow progression. CONCLUSIONS AND RELEVANCE: An ANO10 mutation is responsible for ARCA that is mainly characterized by cerebellar atrophy and lack of peripheral neuropathy. We therefore suggest naming this entity autosomal recessive cerebellar ataxia type 3 (ARCA3).


Assuntos
Encéfalo/patologia , Proteínas de Membrana/genética , Degenerações Espinocerebelares/genética , Adolescente , Adulto , Anoctaminas , Encéfalo/fisiopatologia , Estudos de Coortes , Feminino , Estudos de Associação Genética , Humanos , Imagem por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Mutação , Degenerações Espinocerebelares/patologia , Degenerações Espinocerebelares/fisiopatologia , Adulto Jovem
14.
Brain ; 137(Pt 2): 411-9, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24369382

RESUMO

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.


Assuntos
Ataxia Cerebelar/genética , Epilepsia/genética , Deficiência Intelectual/genética , Mutação de Sentido Incorreto/genética , Oxirredutases/genética , Proteínas Supressoras de Tumor/genética , Adolescente , Adulto , Sequência de Aminoácidos , Animais , Células Cultivadas , Ataxia Cerebelar/diagnóstico , Ataxia Cerebelar/epidemiologia , Epilepsia/diagnóstico , Epilepsia/epidemiologia , Feminino , Humanos , Deficiência Intelectual/diagnóstico , Deficiência Intelectual/epidemiologia , Masculino , Camundongos , Camundongos da Linhagem 129 , Camundongos Endogâmicos C57BL , Camundongos Knockout , Dados de Sequência Molecular , Linhagem , Polimorfismo de Nucleotídeo Único , Estrutura Secundária de Proteína , Arábia Saudita/epidemiologia , Oxidorredutase com Domínios WW , Adulto Jovem
15.
Orphanet J Rare Dis ; 8: 173, 2013 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-24164873

RESUMO

Autosomal recessive cerebellar ataxia 2 (ARCA2) is a recently identified recessive ataxia due to ubiquinone deficiency and biallelic mutations in the ADCK3 gene. The phenotype of the twenty-one patients reported worldwide varies greatly. Thus, it is difficult to decide which ataxic patients are good candidates for ADCK3 screening without evidence of ubiquinone deficiency. We report here the clinical and molecular data of 10 newly diagnosed patients from seven families and update the disease history of four additional patients reported in previous articles to delineate the clinical spectrum of ARCA2 phenotype and to provide a guide to the molecular diagnosis. First signs occurred before adulthood in all 14 patients. Cerebellar atrophy appeared in all instances. The progressivity and severity of ataxia varied greatly, but no patients had the typical inexorable ataxic course that characterizes other childhood-onset recessive ataxias. The ataxia was frequently associated with other neurological signs. Importantly, stroke-like episodes contributed to significant deterioration of the neurological status in two patients. Ubidecarenone therapy markedly improved the movement disorders, including ataxia, in two other patients. The 7 novel ADCK3 mutations found in the 10 new patients were two missense and five truncating mutations. There was no apparent correlation between the genotype and the phenotype. Our series reveals that the clinical spectrum of ARCA2 encompasses a range of ataxic phenotypes. On one end, it may manifest as a pure ataxia with very slow progressivity and, on the other end, as a severe infantile encephalopathy with cerebellar atrophy. The phenotype of most patients, however, lies in between. It is characterized by a very slowly progressive or apparently stable ataxia associated with other signs of central nervous system involvement. We suggest undergoing the molecular analysis of ADCK3 in patients with this phenotype and in those with cerebellar atrophy and a stroke-like episode. The diagnosis of patients with a severe ARCA2 phenotype may also be performed on the basis of biological data, i.e. low ubiquinone level or functional evidence of ubiquinone deficiency. This diagnosis is crucial since the neurological status of some patients may be improved by ubiquinone therapy.


Assuntos
Ataxia Cerebelar/diagnóstico , Adolescente , Adulto , Ataxia Cerebelar/patologia , Ataxia Cerebelar/fisiopatologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Fenótipo , Adulto Jovem
16.
Acta Neuropathol ; 126(3): 427-42, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23820807

RESUMO

L1 syndrome results from mutations in the L1CAM gene located at Xq28. It encompasses a wide spectrum of diseases, X-linked hydrocephalus being the most severe phenotype detected in utero, and whose pathophysiology is incompletely understood. The aim of this study was to report detailed neuropathological data from patients with mutations, to delineate the neuropathological criteria required for L1CAM gene screening in foetuses by characterizing the sensitivity, specificity and positive predictive value of the cardinal signs, and to discuss the main differential diagnoses in non-mutated foetuses in order to delineate closely related conditions without L1CAM mutations. Neuropathological data from 138 cases referred to our genetic laboratory for screening of the L1CAM gene were retrospectively reviewed. Fifty-seven cases had deleterious L1CAM mutations. Of these, 100 % had hydrocephalus, 88 % adducted thumbs, 98 % pyramidal tract agenesis/hypoplasia, 90 % stenosis of the aqueduct of Sylvius and 68 % agenesis/hypoplasia of the corpus callosum. Two foetuses had L1CAM mutations of unknown significance. Seventy-nine cases had no L1CAM mutations; these were subdivided into four groups: (1) hydrocephalus sometimes associated with corpus callosum agenesis (44 %); (2) atresia/forking of the aqueduct of Sylvius/rhombencephalosynapsis spectrum (27 %); (3) syndromic hydrocephalus (9 %), and (4) phenocopies with no mutations in the L1CAM gene (20 %) and in whom family history strongly suggested an autosomal recessive mode of transmission. These data underline the existence of closely related clinical entities whose molecular bases are currently unknown. The identification of the causative genes would greatly improve our knowledge of the defective pathways involved in these cerebral malformations.


Assuntos
Aqueduto do Mesencéfalo/anormalidades , Aqueduto do Mesencéfalo/patologia , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Hidrocefalia/patologia , Doenças do Sistema Nervoso/patologia , Anormalidades Múltiplas/genética , Anormalidades Múltiplas/patologia , Feminino , Humanos , Recém-Nascido , Mutação/genética , Doenças do Sistema Nervoso/genética , Molécula L1 de Adesão de Célula Nervosa/genética , Linhagem , Fenótipo , Gravidez
17.
Neurogenetics ; 13(1): 49-59, 2012 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-22222883

RESUMO

Mutations in the gene encoding the neural cell adhesion molecule L1CAM cause several neurological disorders collectively referred to as L1 syndrome. We report here a family case of X-linked hydrocephalus in which an obligate female carrier has two exonic L1CAM missense mutations in trans substituting amino acids in the first (p.W635C) or second (p.V768I) fibronectin-type III domains. We performed various biochemical and cell biological in vitro assays to evaluate the pathogenicity of these variants. Mutant L1-W635C protein accumulates in the endoplasmic reticulum (ER), is not transported into axons, and fails to promote L1CAM-mediated cell-cell adhesion as well as neurite growth. Immunoprecipitation experiments show that L1-W635C associates with the molecular ER chaperone calnexin and is modified by poly-ubiquitination. The mutant L1-V768I protein localizes at the cell surface, is not retained in the ER, and promotes neurite growth similar to wild-type L1CAM. However, the p.V768I mutation impairs L1CAM-mediated cell-cell adhesion albeit less severe than L1-W635C. These data indicate that p.W635C is a novel loss-of-function L1 syndrome mutation. The p.V768I mutation may represent a non-pathogenic variant or a variant associated with low penetrance. The poly-ubiquitination of L1-W635C and its association with the ER chaperone calnexin provide further insights into the molecular mechanisms underlying defective cell surface trafficking of L1CAM in L1 syndrome.


Assuntos
Éxons , Doenças Genéticas Ligadas ao Cromossomo X/genética , Variação Genética , Hidrocefalia/genética , Molécula L1 de Adesão de Célula Nervosa/genética , Adulto , Linhagem Celular , Aqueduto do Mesencéfalo/anormalidades , Aqueduto do Mesencéfalo/metabolismo , Aqueduto do Mesencéfalo/patologia , Análise Mutacional de DNA , Feminino , Doenças Genéticas Ligadas ao Cromossomo X/metabolismo , Doenças Genéticas Ligadas ao Cromossomo X/patologia , Humanos , Hidrocefalia/metabolismo , Hidrocefalia/patologia , Masculino , Pessoa de Meia-Idade , Mutação , Neurônios/citologia , Neurônios/fisiologia , Linhagem
18.
Genet Test Mol Biomarkers ; 15(7-8): 469-74, 2011 Jul-Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21413874

RESUMO

Copy number variations in the human genome are commonly detected using genome-wide high-resolution screening methods such as array-comparative genomic hybridization. To confirm these copy number variations, we have used an assay based on a semiquantitative multiplex polymerase chain reaction (PCR) of short unlabeled fragments and performed on the microfluidic Bio-Rad Experion system. We have compared the performance of this semiquantitative multiplex PCR of short unlabeled fragments assay with that of the semiquantitative multiplex PCR of short fluorescent fragments assay and have shown that its repeatability and reproducibility are very satisfying, with a relative standard deviation lower than 6.5%. We conclude that this robust and sensitive technology provides reliable data for the confirmation of rearrangements detected by array-comparative genomic hybridization.


Assuntos
Hibridização Genômica Comparativa/métodos , Dosagem de Genes , Genoma Humano/genética , Reação em Cadeia da Polimerase/métodos , Feminino , Variação Genética , Humanos , Masculino , Reprodutibilidade dos Testes
19.
Am J Hum Genet ; 87(6): 813-9, 2010 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-21092923

RESUMO

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.


Assuntos
Ataxia Cerebelar/genética , Genes Recessivos , Homozigoto , Proteínas de Membrana/genética , Mutação , Proteínas de Neoplasias/genética , Anoctamina-1 , Canais de Cloreto , Humanos , Polimorfismo de Nucleotídeo Único
20.
Brain ; 133(Pt 8): 2439-47, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20826435

RESUMO

We have identified a novel form of recessive ataxia that segregates in three children of a large consanguineous Saudi Arabian family. The three patients presented with childhood onset gait and limb ataxia, dysarthria and had limited walking without aid into their teenage years. Two patients developed epilepsy at 7 months without relapse after treatment, and mental retardation. Linkage studies allowed us to identify a single locus that segregated with the disease on chromosome 3q28-qter. Mutation screening of all coding sequences revealed a single nucleotide deletion, 2927delC, in exon 19 of the KIAA0226 gene, which results in a frame shift of the C-terminal domain (p.Ala943ValfsX146). The KIAA0226 gene encodes a protein that we named rundataxin, with two conserved domains: an N-terminal RUN domain and a C-terminal domain containing a diacylglycerol binding-like motif. The closest paralogue of rundataxin, the plekstrin homology domain family member M1, has been shown to colocalize with Rab7, a small GTPase associated with late endosomes/lysosomes, suggesting that rundataxin may also be associated with vesicular trafficking and signalling pathways through its RUN and diacylglycerol binding-like domains. The rundataxin pathway appears therefore distinct from the ataxia pathways involving deficiency in mitochondrial or nuclear proteins and broadens the range of mechanisms leading to recessive ataxias.


Assuntos
Ataxia/genética , Mutação da Fase de Leitura , Peptídeos e Proteínas de Sinalização Intracelular/genética , Adolescente , Ataxia/patologia , Sequência de Bases , Encéfalo/patologia , Mapeamento Cromossômico , Consanguinidade , Análise Mutacional de DNA , Família , Feminino , Humanos , Repetições de Microssatélites , Linhagem , Mutação Puntual , Polimorfismo de Nucleotídeo Único , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Arábia Saudita , Deleção de Sequência , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA