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Journal ArticleDOI

Systematic resequencing of X-chromosome synaptic genes in autism spectrum disorder and schizophrenia.

TL;DR: Test the hypothesis that rare variants in many different genes, including de novo variants, could predispose to these conditions in a fraction of cases, and identified >200 non-synonymous variants, with an excess of rare damaging variants, which suggest the presence of disease-causing mutations.
Abstract: Autism spectrum disorder (ASD) and schizophrenia (SCZ) are two common neurodevelopmental syndromes that result from the combined effects of environmental and genetic factors. We set out to test the hypothesis that rare variants in many different genes, including de novo variants, could predispose to these conditions in a fraction of cases. In addition, for both disorders, males are either more significantly or more severely affected than females, which may be explained in part by X-linked genetic factors. Therefore, we directly sequenced 111 X-linked synaptic genes in individuals with ASD (n=142; 122 males and 20 females) or SCZ (n=143; 95 males and 48 females). We identified >200 non-synonymous variants, with an excess of rare damaging variants, which suggest the presence of disease-causing mutations. Truncating mutations in genes encoding the calcium-related protein IL1RAPL1 (already described in Piton et al. Hum Mol Genet 2008) and the monoamine degradation enzyme monoamine oxidase B were found in ASD and SCZ, respectively. Moreover, several promising non-synonymous rare variants were identified in genes encoding proteins involved in regulation of neurite outgrowth and other various synaptic functions (MECP2, TM4SF2/TSPAN7, PPP1R3F, PSMD10, MCF2, SLITRK2, GPRASP2, and OPHN1).

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Citations
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Journal ArticleDOI
TL;DR: By examining de novo and rare inherited single-nucleotide and structural variations in genes previously reported to be associated with ASD or other neurodevelopmental disorders, it is found that some of the affected siblings carried different ASD-relevant mutations.
Abstract: Autism spectrum disorder (ASD) is genetically heterogeneous, with evidence for hundreds of susceptibility loci. Previous microarray and exome-sequencing studies have examined portions of the genome in simplex families (parents and one ASD-affected child) having presumed sporadic forms of the disorder. We used whole-genome sequencing (WGS) of 85 quartet families (parents and two ASD-affected siblings), consisting of 170 individuals with ASD, to generate a comprehensive data resource encompassing all classes of genetic variation (including noncoding variants) and accompanying phenotypes, in apparently familial forms of ASD. By examining de novo and rare inherited single-nucleotide and structural variations in genes previously reported to be associated with ASD or other neurodevelopmental disorders, we found that some (69.4%) of the affected siblings carried different ASD-relevant mutations. These siblings with discordant mutations tended to demonstrate more clinical variability than those who shared a risk variant. Our study emphasizes that substantial genetic heterogeneity exists in ASD, necessitating the use of WGS to delineate all genic and non-genic susceptibility variants in research and in clinical diagnostics.

470 citations

Journal ArticleDOI
TL;DR: Results suggest that WGS and thorough bioinformatic analyses for de novo and rare inherited mutations will improve the detection of genetic variants likely to be associated with ASD or its accompanying clinical symptoms.
Abstract: Autism Spectrum Disorder (ASD) demonstrates high heritability and familial clustering, yet the genetic causes remain only partially understood as a result of extensive clinical and genomic heterogeneity. Whole-genome sequencing (WGS) shows promise as a tool for identifying ASD risk genes as well as unreported mutations in known loci, but an assessment of its full utility in an ASD group has not been performed. We used WGS to examine 32 families with ASD to detect de novo or rare inherited genetic variants predicted to be deleterious (loss-of-function and damaging missense mutations). Among ASD probands, we identified deleterious de novo mutations in six of 32 (19%) families and X-linked or autosomal inherited alterations in ten of 32 (31%) families (some had combinations of mutations). The proportion of families identified with such putative mutations was larger than has been previously reported; this yield was in part due to the comprehensive and uniform coverage afforded by WGS. Deleterious variants were found in four unrecognized, nine known, and eight candidate ASD risk genes. Examples include CAPRIN1 and AFF2 (both linked to FMR1, which is involved in fragile X syndrome), VIP (involved in social-cognitive deficits), and other genes such as SCN2A and KCNQ2 (linked to epilepsy), NRXN1, and CHD7, which causes ASD-associated CHARGE syndrome. Taken together, these results suggest that WGS and thorough bioinformatic analyses for de novo and rare inherited mutations will improve the detection of genetic variants likely to be associated with ASD or its accompanying clinical symptoms.

441 citations


Cites methods from "Systematic resequencing of X-chromo..."

  • ...We evaluated the approach by using the validation results of (1) all genomic de novo SNVs in one family (2-1266) and (2) Sanger...

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  • ...tions in the whole genomes of one trio (2-1266) were selected randomly, and all the 38 exonic de novo and ASD-relevant variants were validated experimentally by Sanger sequencing...

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Journal ArticleDOI
TL;DR: NRXN2 disruption to the pathogenesis of ASD is linked for the first time and the involvement of NRXN1 in SCZ is strengthened, supporting the notion of a common genetic mechanism in these disorders.
Abstract: Growing genetic evidence is converging in favor of common pathogenic mechanisms for autism spectrum disorders (ASD), intellectual disability (ID or mental retardation) and schizophrenia (SCZ), three neurodevelopmental disorders affecting cognition and behavior. Copy number variations and deleterious mutations in synaptic organizing proteins including NRXN1 have been associated with these neurodevelopmental disorders, but no such associations have been reported for NRXN2 or NRXN3. From resequencing the three neurexin genes in individuals affected by ASD (n = 142), SCZ (n = 143) or non-syndromic ID (n = 94), we identified a truncating mutation in NRXN2 in a patient with ASD inherited from a father with severe language delay and family history of SCZ. We also identified a de novo truncating mutation in NRXN1 in a patient with SCZ, and other potential pathogenic ASD mutations. These truncating mutations result in proteins that fail to promote synaptic differentiation in neuron coculture and fail to bind either of the established postsynaptic binding partners LRRTM2 or NLGN2 in cell binding assays. Our findings link NRXN2 disruption to the pathogenesis of ASD for the first time and further strengthen the involvement of NRXN1 in SCZ, supporting the notion of a common genetic mechanism in these disorders.

244 citations

Journal ArticleDOI
TL;DR: It is proposed that similar reassessment of reported mutations (and genes) with the use of data from large-scale human exome sequencing would be relevant for a wide range of other genetic diseases.
Abstract: Because of the unbalanced sex ratio (1.3–1.4 to 1) observed in intellectual disability (ID) and the identification of large ID-affected families showing X-linked segregation, much attention has been focused on the genetics of X-linked ID (XLID). Mutations causing monogenic XLID have now been reported in over 100 genes, most of which are commonly included in XLID diagnostic gene panels. Nonetheless, the boundary between true mutations and rare non-disease-causing variants often remains elusive. The sequencing of a large number of control X chromosomes, required for avoiding false-positive results, was not systematically possible in the past. Such information is now available thanks to large-scale sequencing projects such as the National Heart, Lung, and Blood (NHLBI) Exome Sequencing Project, which provides variation information on 10,563 X chromosomes from the general population. We used this NHLBI cohort to systematically reassess the implication of 106 genes proposed to be involved in monogenic forms of XLID. We particularly question the implication in XLID of ten of them (AGTR2, MAGT1, ZNF674, SRPX2, ATP6AP2, ARHGEF6, NXF5, ZCCHC12, ZNF41, and ZNF81), in which truncating variants or previously published mutations are observed at a relatively high frequency within this cohort. We also highlight 15 other genes (CCDC22, CLIC2, CNKSR2, FRMPD4, HCFC1, IGBP1, KIAA2022, KLF8, MAOA, NAA10, NLGN3, RPL10, SHROOM4, ZDHHC15, and ZNF261) for which replication studies are warranted. We propose that similar reassessment of reported mutations (and genes) with the use of data from large-scale human exome sequencing would be relevant for a wide range of other genetic diseases.

243 citations

Journal ArticleDOI
Hao Hu1, Stefan A. Haas1, Jamel Chelly2, Jamel Chelly3, H Van Esch4, Martine Raynaud3, A.P.M. de Brouwer5, Stefanie Weinert6, Guy Froyen4, Suzanna G.M. Frints7, Frédéric Laumonnier3, Tomasz Zemojtel1, Michael I. Love1, Hugues Richard1, Anne-Katrin Emde1, M Bienek1, C Jensen1, Melanie Hambrock1, Utz Fischer1, Claudia Langnick, Mirjam Feldkamp, Willemijn M. Wissink-Lindhout5, Nicolas Lebrun3, Nicolas Lebrun2, L. Castelnau3, L. Castelnau2, Julien Rucci2, Julien Rucci3, R. Montjean3, R. Montjean2, Olivier Dorseuil3, Olivier Dorseuil2, Pierre Billuart3, Pierre Billuart2, T. Stuhlmann6, Marie Shaw8, Mark A. Corbett8, Alison Gardner8, Saffron A.G. Willis-Owen8, Saffron A.G. Willis-Owen9, C Tan8, Kathryn Friend10, Stefanie Belet4, K. E. P. van Roozendaal7, M Jimenez-Pocquet, Marie-Pierre Moizard3, Nathalie Ronce3, Ruping Sun1, Sean O'Keeffe1, Ramu Chenna1, A. van Bömmel1, Jonathan Göke1, Anna Hackett, Michael Field, Louise Christie, Jackie Boyle, Eric Haan10, Eric Haan8, John Nelson11, Gillian Turner, Gareth Baynam, Gabriele Gillessen-Kaesbach12, Ulrich Müller13, Daniela Steinberger13, Bartłomiej Budny14, Magdalena Badura-Stronka14, Anna Latos-Bielenska14, Lilian Bomme Ousager15, Peter Wieacker, G. Rodríguez Criado, Marie-Louise Bondeson16, Göran Annerén16, Andreas Dufke, Monika Cohen, L. Van Maldergem17, Catherine Vincent-Delorme, Bernard Echenne, B. Simon-Bouy, Tjitske Kleefstra5, Marjolein H. Willemsen5, J. P. Fryns4, Koenraad Devriendt4, Reinhard Ullmann1, Martin Vingron1, Klaus Wrogemann18, Klaus Wrogemann1, Thomas F. Wienker1, Andreas Tzschach1, H Van Bokhoven5, Jozef Gecz8, Thomas J. Jentsch6, Wei Chen1, Hans-Hilger Ropers1, Vera M. Kalscheuer1 
TL;DR: It is suggested that systematic sequencing of all X-chromosomal genes in a cohort of patients with genetic evidence for X- Chromosome locus involvement may resolve up to 58% of Fragile X-negative cases.
Abstract: X-linked intellectual disability (XLID) is a clinically and genetically heterogeneous disorder. During the past two decades in excess of 100 X-chromosome ID genes have been identified. Yet, a large number of families mapping to the X-chromosome remained unresolved suggesting that more XLID genes or loci are yet to be identified. Here, we have investigated 405 unresolved families with XLID. We employed massively parallel sequencing of all X-chromosome exons in the index males. The majority of these males were previously tested negative for copy number variations and for mutations in a subset of known XLID genes by Sanger sequencing. In total, 745 X-chromosomal genes were screened. After stringent filtering, a total of 1297 non-recurrent exonic variants remained for prioritization. Co-segregation analysis of potential clinically relevant changes revealed that 80 families (20%) carried pathogenic variants in established XLID genes. In 19 families, we detected likely causative protein truncating and missense variants in 7 novel and validated XLID genes (CLCN4, CNKSR2, FRMPD4, KLHL15, LAS1L, RLIM and USP27X) and potentially deleterious variants in 2 novel candidate XLID genes (CDK16 and TAF1). We show that the CLCN4 and CNKSR2 variants impair protein functions as indicated by electrophysiological studies and altered differentiation of cultured primary neurons from Clcn4(-/-) mice or after mRNA knock-down. The newly identified and candidate XLID proteins belong to pathways and networks with established roles in cognitive function and intellectual disability in particular. We suggest that systematic sequencing of all X-chromosomal genes in a cohort of patients with genetic evidence for X-chromosome locus involvement may resolve up to 58% of Fragile X-negative cases.

231 citations

References
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Journal ArticleDOI
TL;DR: SIFT is a program that predicts whether an amino acid substitution affects protein function so that users can prioritize substitutions for further study and can distinguish between functionally neutral and deleterious amino acid changes in mutagenesis studies and on human polymorphisms.
Abstract: Single nucleotide polymorphism (SNP) studies and random mutagenesis projects identify amino acid substitutions in protein-coding regions. Each substitution has the potential to affect protein function. SIFT (Sorting Intolerant From Tolerant) is a program that predicts whether an amino acid substitution affects protein function so that users can prioritize substitutions for further study. We have shown that SIFT can distinguish between functionally neutral and deleterious amino acid changes in mutagenesis studies and on human polymorphisms. SIFT is available at http://blocks.fhcrc.org/sift/SIFT.html.

5,318 citations

Journal ArticleDOI
Shaun Purcell1, Shaun Purcell2, Naomi R. Wray3, Jennifer Stone1, Jennifer Stone2, Peter M. Visscher, Michael Conlon O'Donovan4, Patrick F. Sullivan5, Pamela Sklar2, Pamela Sklar1, Douglas M. Ruderfer, Andrew McQuillin, Derek W. Morris6, Colm O'Dushlaine6, Aiden Corvin6, Peter Holmans4, Stuart MacGregor3, Hugh Gurling, Douglas Blackwood7, Nicholas John Craddock5, Michael Gill6, Christina M. Hultman8, Christina M. Hultman9, George Kirov4, Paul Lichtenstein8, Walter J. Muir7, Michael John Owen4, Carlos N. Pato10, Edward M. Scolnick2, Edward M. Scolnick1, David St Clair, Nigel Williams4, Lyudmila Georgieva4, Ivan Nikolov4, Nadine Norton4, Hywel Williams4, Draga Toncheva, Vihra Milanova, Emma Flordal Thelander8, Patrick Sullivan11, Elaine Kenny6, Emma M. Quinn6, Khalid Choudhury12, Susmita Datta12, Jonathan Pimm12, Srinivasa Thirumalai13, Vinay Puri12, Robert Krasucki12, Jacob Lawrence12, Digby Quested14, Nicholas Bass12, Caroline Crombie15, Gillian Fraser15, Soh Leh Kuan, Nicholas Walker, Kevin A. McGhee7, Ben S. Pickard16, P. Malloy7, Alan W Maclean7, Margaret Van Beck7, Michele T. Pato10, Helena Medeiros10, Frank A. Middleton17, Célia Barreto Carvalho10, Christopher P. Morley17, Ayman H. Fanous, David V. Conti10, James A. Knowles10, Carlos Ferreira, António Macedo18, M. Helena Azevedo18, Andrew Kirby1, Andrew Kirby2, Manuel A. R. Ferreira2, Manuel A. R. Ferreira1, Mark J. Daly1, Mark J. Daly2, Kimberly Chambert1, Finny G Kuruvilla1, Stacey Gabriel1, Kristin G. Ardlie1, Jennifer L. Moran1 
06 Aug 2009-Nature
TL;DR: The extent to which common genetic variation underlies the risk of schizophrenia is shown, using two analytic approaches, and the major histocompatibility complex is implicate, which is shown to involve thousands of common alleles of very small effect.
Abstract: Schizophrenia is a severe mental disorder with a lifetime risk of about 1%, characterized by hallucinations, delusions and cognitive deficits, with heritability estimated at up to 80%(1,2). We performed a genome-wide association study of 3,322 European individuals with schizophrenia and 3,587 controls. Here we show, using two analytic approaches, the extent to which common genetic variation underlies the risk of schizophrenia. First, we implicate the major histocompatibility complex. Second, we provide molecular genetic evidence for a substantial polygenic component to the risk of schizophrenia involving thousands of common alleles of very small effect. We show that this component also contributes to the risk of bipolar disorder, but not to several non-psychiatric diseases.

4,573 citations

Journal ArticleDOI
TL;DR: This study reports the first disease-causing mutations in RTT and points to abnormal epigenetic regulation as the mechanism underlying the pathogenesis of RTT.
Abstract: Rett syndrome (RTT, MIM 312750) is a progressive neurodevelopmental disorder and one of the most common causes of mental retardation in females, with an incidence of 1 in 10,000-15,000 (ref. 2). Patients with classic RTT appear to develop normally until 6-18 months of age, then gradually lose speech and purposeful hand use, and develop microcephaly, seizures, autism, ataxia, intermittent hyperventilation and stereotypic hand movements. After initial regression, the condition stabilizes and patients usually survive into adulthood. As RTT occurs almost exclusively in females, it has been proposed that RTT is caused by an X-linked dominant mutation with lethality in hemizygous males. Previous exclusion mapping studies using RTT families mapped the locus to Xq28 (refs 6,9,10,11). Using a systematic gene screening approach, we have identified mutations in the gene (MECP2 ) encoding X-linked methyl-CpG-binding protein 2 (MeCP2) as the cause of some cases of RTT. MeCP2 selectively binds CpG dinucleotides in the mammalian genome and mediates transcriptional repression through interaction with histone deacetylase and the corepressor SIN3A (refs 12,13). In 5 of 21 sporadic patients, we found 3 de novo missense mutations in the region encoding the highly conserved methyl-binding domain (MBD) as well as a de novo frameshift and a de novo nonsense mutation, both of which disrupt the transcription repression domain (TRD). In two affected half-sisters of a RTT family, we found segregation of an additional missense mutation not detected in their obligate carrier mother. This suggests that the mother is a germline mosaic for this mutation. Our study reports the first disease-causing mutations in RTT and points to abnormal epigenetic regulation as the mechanism underlying the pathogenesis of RTT.

4,503 citations

Journal ArticleDOI
31 May 1991-Cell
TL;DR: A fragile X site-induced breakpoint cluster region that exhibits length variation in fragile X chromosomes is identified and localization of the brain-expressed FMR-1 gene to this EcoRI fragment suggests the involvement of this gene in the phenotypic expression of the fragile X syndrome.

3,290 citations

Journal ArticleDOI
TL;DR: The findings indicate that autism is under a high degree of genetic control and suggest the involvement of multiple genetic loci.
Abstract: Two previous epidemiological studies of autistic twins suggested that autism was predominantly genetically determined, although the findings with regard to a broader phenotype of cognitive, and possibly social, abnormalities were contradictory. Obstetric and perinatal hazards were also invoked as environmentally determined aetiological factors. The first British twin sample has been re-examined and a second total population sample of autistic twins recruited. In the combined sample 60% of monozygotic (MZ) pairs were concordant for autism versus no dizygotic (DZ) pairs; 92% of MZ pairs were concordant for a broader spectrum of related cognitive or social abnormalities versus 10% of DZ pairs. The findings indicate that autism is under a high degree of genetic control and suggest the involvement of multiple genetic loci. Obstetric hazards usually appear to be consequences of genetically influenced abnormal development, rather than independent aetiological factors. Few new cases had possible medical aetiologies, refuting claims that recognized disorders are common aetiological influences.

2,378 citations

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