PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-15 (15)
 

Clipboard (0)
None

Select a Filter Below

Journals
more »
Year of Publication
author:("Cai, guiding")
1.  Biological Insights From 108 Schizophrenia-Associated Genetic Loci 
Ripke, Stephan | Neale, Benjamin M | Corvin, Aiden | Walters, James TR | Farh, Kai-How | Holmans, Peter A | Lee, Phil | Bulik-Sullivan, Brendan | Collier, David A | Huang, Hailiang | Pers, Tune H | Agartz, Ingrid | Agerbo, Esben | Albus, Margot | Alexander, Madeline | Amin, Farooq | Bacanu, Silviu A | Begemann, Martin | Belliveau, Richard A | Bene, Judit | Bergen, Sarah E | Bevilacqua, Elizabeth | Bigdeli, Tim B | Black, Donald W | Bruggeman, Richard | Buccola, Nancy G | Buckner, Randy L | Byerley, William | Cahn, Wiepke | Cai, Guiqing | Campion, Dominique | Cantor, Rita M | Carr, Vaughan J | Carrera, Noa | Catts, Stanley V | Chambert, Kimberley D | Chan, Raymond CK | Chan, Ronald YL | Chen, Eric YH | Cheng, Wei | Cheung, Eric FC | Chong, Siow Ann | Cloninger, C Robert | Cohen, David | Cohen, Nadine | Cormican, Paul | Craddock, Nick | Crowley, James J | Curtis, David | Davidson, Michael | Davis, Kenneth L | Degenhardt, Franziska | Del Favero, Jurgen | Demontis, Ditte | Dikeos, Dimitris | Dinan, Timothy | Djurovic, Srdjan | Donohoe, Gary | Drapeau, Elodie | Duan, Jubao | Dudbridge, Frank | Durmishi, Naser | Eichhammer, Peter | Eriksson, Johan | Escott-Price, Valentina | Essioux, Laurent | Fanous, Ayman H | Farrell, Martilias S | Frank, Josef | Franke, Lude | Freedman, Robert | Freimer, Nelson B | Friedl, Marion | Friedman, Joseph I | Fromer, Menachem | Genovese, Giulio | Georgieva, Lyudmila | Giegling, Ina | Giusti-Rodríguez, Paola | Godard, Stephanie | Goldstein, Jacqueline I | Golimbet, Vera | Gopal, Srihari | Gratten, Jacob | de Haan, Lieuwe | Hammer, Christian | Hamshere, Marian L | Hansen, Mark | Hansen, Thomas | Haroutunian, Vahram | Hartmann, Annette M | Henskens, Frans A | Herms, Stefan | Hirschhorn, Joel N | Hoffmann, Per | Hofman, Andrea | Hollegaard, Mads V | Hougaard, David M | Ikeda, Masashi | Joa, Inge | Julià, Antonio | Kahn, René S | Kalaydjieva, Luba | Karachanak-Yankova, Sena | Karjalainen, Juha | Kavanagh, David | Keller, Matthew C | Kennedy, James L | Khrunin, Andrey | Kim, Yunjung | Klovins, Janis | Knowles, James A | Konte, Bettina | Kucinskas, Vaidutis | Kucinskiene, Zita Ausrele | Kuzelova-Ptackova, Hana | Kähler, Anna K | Laurent, Claudine | Lee, Jimmy | Lee, S Hong | Legge, Sophie E | Lerer, Bernard | Li, Miaoxin | Li, Tao | Liang, Kung-Yee | Lieberman, Jeffrey | Limborska, Svetlana | Loughland, Carmel M | Lubinski, Jan | Lönnqvist, Jouko | Macek, Milan | Magnusson, Patrik KE | Maher, Brion S | Maier, Wolfgang | Mallet, Jacques | Marsal, Sara | Mattheisen, Manuel | Mattingsdal, Morten | McCarley, Robert W | McDonald, Colm | McIntosh, Andrew M | Meier, Sandra | Meijer, Carin J | Melegh, Bela | Melle, Ingrid | Mesholam-Gately, Raquelle I | Metspalu, Andres | Michie, Patricia T | Milani, Lili | Milanova, Vihra | Mokrab, Younes | Morris, Derek W | Mors, Ole | Murphy, Kieran C | Murray, Robin M | Myin-Germeys, Inez | Müller-Myhsok, Bertram | Nelis, Mari | Nenadic, Igor | Nertney, Deborah A | Nestadt, Gerald | Nicodemus, Kristin K | Nikitina-Zake, Liene | Nisenbaum, Laura | Nordin, Annelie | O’Callaghan, Eadbhard | O’Dushlaine, Colm | O’Neill, F Anthony | Oh, Sang-Yun | Olincy, Ann | Olsen, Line | Van Os, Jim | Pantelis, Christos | Papadimitriou, George N | Papiol, Sergi | Parkhomenko, Elena | Pato, Michele T | Paunio, Tiina | Pejovic-Milovancevic, Milica | Perkins, Diana O | Pietiläinen, Olli | Pimm, Jonathan | Pocklington, Andrew J | Powell, John | Price, Alkes | Pulver, Ann E | Purcell, Shaun M | Quested, Digby | Rasmussen, Henrik B | Reichenberg, Abraham | Reimers, Mark A | Richards, Alexander L | Roffman, Joshua L | Roussos, Panos | Ruderfer, Douglas M | Salomaa, Veikko | Sanders, Alan R | Schall, Ulrich | Schubert, Christian R | Schulze, Thomas G | Schwab, Sibylle G | Scolnick, Edward M | Scott, Rodney J | Seidman, Larry J | Shi, Jianxin | Sigurdsson, Engilbert | Silagadze, Teimuraz | Silverman, Jeremy M | Sim, Kang | Slominsky, Petr | Smoller, Jordan W | So, Hon-Cheong | Spencer, Chris C A | Stahl, Eli A | Stefansson, Hreinn | Steinberg, Stacy | Stogmann, Elisabeth | Straub, Richard E | Strengman, Eric | Strohmaier, Jana | Stroup, T Scott | Subramaniam, Mythily | Suvisaari, Jaana | Svrakic, Dragan M | Szatkiewicz, Jin P | Söderman, Erik | Thirumalai, Srinivas | Toncheva, Draga | Tosato, Sarah | Veijola, Juha | Waddington, John | Walsh, Dermot | Wang, Dai | Wang, Qiang | Webb, Bradley T | Weiser, Mark | Wildenauer, Dieter B | Williams, Nigel M | Williams, Stephanie | Witt, Stephanie H | Wolen, Aaron R | Wong, Emily HM | Wormley, Brandon K | Xi, Hualin Simon | Zai, Clement C | Zheng, Xuebin | Zimprich, Fritz | Wray, Naomi R | Stefansson, Kari | Visscher, Peter M | Adolfsson, Rolf | Andreassen, Ole A | Blackwood, Douglas HR | Bramon, Elvira | Buxbaum, Joseph D | Børglum, Anders D | Cichon, Sven | Darvasi, Ariel | Domenici, Enrico | Ehrenreich, Hannelore | Esko, Tõnu | Gejman, Pablo V | Gill, Michael | Gurling, Hugh | Hultman, Christina M | Iwata, Nakao | Jablensky, Assen V | Jönsson, Erik G | Kendler, Kenneth S | Kirov, George | Knight, Jo | Lencz, Todd | Levinson, Douglas F | Li, Qingqin S | Liu, Jianjun | Malhotra, Anil K | McCarroll, Steven A | McQuillin, Andrew | Moran, Jennifer L | Mortensen, Preben B | Mowry, Bryan J | Nöthen, Markus M | Ophoff, Roel A | Owen, Michael J | Palotie, Aarno | Pato, Carlos N | Petryshen, Tracey L | Posthuma, Danielle | Rietschel, Marcella | Riley, Brien P | Rujescu, Dan | Sham, Pak C | Sklar, Pamela | St Clair, David | Weinberger, Daniel R | Wendland, Jens R | Werge, Thomas | Daly, Mark J | Sullivan, Patrick F | O’Donovan, Michael C
Nature  2014;511(7510):421-427.
Summary
Schizophrenia is a highly heritable disorder. Genetic risk is conferred by a large number of alleles, including common alleles of small effect that might be detected by genome-wide association studies. Here, we report a multi-stage schizophrenia genome-wide association study of up to 36,989 cases and 113,075 controls. We identify 128 independent associations spanning 108 conservatively defined loci that meet genome-wide significance, 83 of which have not been previously reported. Associations were enriched among genes expressed in brain providing biological plausibility for the findings. Many findings have the potential to provide entirely novel insights into aetiology, but associations at DRD2 and multiple genes involved in glutamatergic neurotransmission highlight molecules of known and potential therapeutic relevance to schizophrenia, and are consistent with leading pathophysiological hypotheses. Independent of genes expressed in brain, associations were enriched among genes expressed in tissues that play important roles in immunity, providing support for the hypothesized link between the immune system and schizophrenia.
doi:10.1038/nature13595
PMCID: PMC4112379  PMID: 25056061
2.  Whole exome sequencing reveals minimal differences between cell line and whole blood derived DNA 
Genomics  2013;102(4):10.1016/j.ygeno.2013.05.005.
Two common sources of DNA for whole exome sequencing (WES) are whole blood (WB) and immortalized lymphoblastoid cell line (LCL). However, it is possible that LCLs have a substantially higher rate of mutation than WB, causing concern for their use in sequencing studies. We compared results from paired WB and LCL DNA samples for 16 subjects, using LCLs of low passage number (<5). Using a standard analysis pipeline we detected a large number of discordant genotype calls (approximately 50 per subject) that we segregated into categories of “confidence” based on read-level quality metrics. From these categories and validation by Sanger sequencing, we estimate that the vast majority of the candidate differences were false positives and that our categories were effective in predicting valid sequence differences, including LCLs with putative mosaicism for the non-reference allele (3–4 per exome). These results validate the use of DNA from LCLs of low passage number for exome sequencing.
doi:10.1016/j.ygeno.2013.05.005
PMCID: PMC3812417  PMID: 23743231
graphical diagnostics; lymphoblastoid cell line; mosaicism; sequence variant call; strand bias; somatic mutation
3.  Evidence against a role for rare ADAM10 mutations in sporadic Alzheimer Disease 
Neurobiology of aging  2010;33(2):416-417.e3.
The Alzheimer amyloid protein precursor (APP) is subject to proteolysis by ADAM10 and ADAM17, precluding the formation of Aβ. Recently, coding variations in ADAM10 resulting in altered function have been reported in familial Alzheimer disease (AD). We carried out a large-scale (n=576: Controls, 271; AD, 305) resequencing study of ADAM10 in sporadic AD. Our results do not support a significant role for ADAM10 mutations in AD. Our results also make it clear that the careful examination of ancestry required in any case-control comparison is especially true with rare variations, where even a very small number of variations might form the basis of scientific conclusions.
doi:10.1016/j.neurobiolaging.2010.03.003
PMCID: PMC4084881  PMID: 20381196
Mutation; rare variation; genetics; association
4.  De novo SCN2A splice site mutation in a boy with Autism spectrum disorder 
BMC Medical Genetics  2014;15:35.
Background
SCN2A is a gene that codes for the alpha subunit of voltage-gated, type II sodium channels, and is highly expressed in the brain. Sodium channel disruptions, such as mutations in SCN2A, may play an important role in psychiatric disorders. Recently, de novo SCN2A mutations in autism spectrum disorder (ASD) have been identified. The current study characterizes a de novo splice site mutation in SCN2A that alters mRNA and protein products.
Case presentation
We describe results from clinical and genetic characterizations of a seven-year-old boy with ASD. Psychiatric interview and gold standard autism diagnostic instruments (ADOS and ADI-R) were used to confirm ASD diagnosis, in addition to performing standardized cognitive and adaptive functioning assessments (Leiter-R and Vineland Adaptive Behavior Scale), and sensory reactivity assessments (Sensory Profile and Sensory Processing Scales). Genetic testing by whole exome sequencing revealed four de novo events, including a splice site mutation c.476 + 1G > A in SCN2A, a missense mutation (c.2263G > A) causing a p.V755I change in the TLE1 gene, and two synonymous mutations (c.2943A > G in the BUB1 gene, and c.1254 T > A in C10orf68 gene). The de novo SCN2A splice site mutation produced a stop codon 10 amino acids downstream, possibly resulting in a truncated protein and/or a nonsense-mediated mRNA decay. The participant met new DSM-5 criteria for ASD, presenting with social and communication impairment, repetitive behaviors, and sensory reactivity issues. The participant’s adaptive and cognitive skills fell in the low range of functioning.
Conclusion
This report indicates that a splice site mutation in SCN2A might be contributing to the risk of ASD. Describing the specific phenotype associated with SCN2A mutations might help to reduce heterogeneity seen in ASD.
doi:10.1186/1471-2350-15-35
PMCID: PMC3994485  PMID: 24650168
DSM-5; autism spectrum disorder; de novo SCN2A splice site mutation
5.  Characterization of SLITRK1 Variation in Obsessive-Compulsive Disorder 
PLoS ONE  2013;8(8):e70376.
Obsessive compulsive disorder (OCD) is a syndrome characterized by recurrent and intrusive thoughts and ritualistic behaviors or mental acts that a person feels compelled to perform. Twin studies, family studies, and segregation analyses provide compelling evidence that OCD has a strong genetic component. The SLITRK1 gene encodes a developmentally regulated stimulator of neurite outgrowth and previous studies have implicated rare variants in this gene in disorders in the OC spectrum, specifically Tourette syndrome (TS) and trichotillomania (TTM). The objective of the current study was to evaluate rare genetic variation in SLITRK1 in risk for OCD and to functionally characterize associated coding variants. We sequenced SLITRK1 coding exons in 381 individuals with OCD as well as in 356 control samples and identified three novel variants in seven individuals. We found that the combined mutation load in OCD relative to controls was significant (p = 0.036). We identified a missense N400I change in an individual with OCD, which was not found in more than 1000 control samples (P<0.05). In addition, we showed the the N400I variant failed to enhance neurite outgrowth in primary neuronal cultures, in contrast to wildtype SLITRK1, which enhanced neurite outgrowth in this assay. These important functional differences in the N400I variant, as compared to the wildtype SLITRK1 sequence, may contribute to OCD and OC spectrum symptoms. A synonymous L63L change identified in an individual with OCD and an additional missense change, T418S, was found in four individuals with OCD and in one individual without an OCD spectrum disorder. Examination of additional samples will help assess the role of rare SLITRK1 variation in OCD and in related psychiatric illness.
doi:10.1371/journal.pone.0070376
PMCID: PMC3749144  PMID: 23990902
6.  Prospective investigation of autism and genotype-phenotype correlations in 22q13 deletion syndrome and SHANK3 deficiency 
Molecular Autism  2013;4:18.
Background
22q13 deletion syndrome, also known as Phelan-McDermid syndrome, is a neurodevelopmental disorder characterized by intellectual disability, hypotonia, delayed or absent speech, and autistic features. SHANK3 has been identified as the critical gene in the neurological and behavioral aspects of this syndrome. The phenotype of SHANK3 deficiency has been described primarily from case studies, with limited evaluation of behavioral and cognitive deficits. The present study used a prospective design and inter-disciplinary clinical evaluations to assess patients with SHANK3 deficiency, with the goal of providing a comprehensive picture of the medical and behavioral profile of the syndrome.
Methods
A serially ascertained sample of patients with SHANK3 deficiency (n = 32) was evaluated by a team of child psychiatrists, neurologists, clinical geneticists, molecular geneticists and psychologists. Patients were evaluated for autism spectrum disorder using the Autism Diagnostic Interview-Revised and the Autism Diagnostic Observation Schedule-G.
Results
Thirty participants with 22q13.3 deletions ranging in size from 101 kb to 8.45 Mb and two participants with de novo SHANK3 mutations were included. The sample was characterized by high rates of autism spectrum disorder: 27 (84%) met criteria for autism spectrum disorder and 24 (75%) for autistic disorder. Most patients (77%) exhibited severe to profound intellectual disability and only five (19%) used some words spontaneously to communicate. Dysmorphic features, hypotonia, gait disturbance, recurring upper respiratory tract infections, gastroesophageal reflux and seizures were also common. Analysis of genotype-phenotype correlations indicated that larger deletions were associated with increased levels of dysmorphic features, medical comorbidities and social communication impairments related to autism. Analyses of individuals with small deletions or point mutations identified features related to SHANK3 haploinsufficiency, including ASD, seizures and abnormal EEG, hypotonia, sleep disturbances, abnormal brain MRI, gastroesophageal reflux, and certain dysmorphic features.
Conclusions
This study supports findings from previous research on the severity of intellectual, motor, and speech impairments seen in SHANK3 deficiency, and highlights the prominence of autism spectrum disorder in the syndrome. Limitations of existing evaluation tools are discussed, along with the need for natural history studies to inform clinical monitoring and treatment development in SHANK3 deficiency.
doi:10.1186/2040-2392-4-18
PMCID: PMC3707861  PMID: 23758760
22q13 deletion syndrome; Autism; Microarrays; Mutation; Phelan-McDermid syndrome; SHANK3
7.  Patterns and rates of exonic de novo mutations in autism spectrum disorders 
Nature  2012;485(7397):242-245.
Autism spectrum disorders (ASD) are believed to have genetic and environmental origins, yet in only a modest fraction of individuals can specific causes be identified1,2. To identify further genetic risk factors, we assess the role of de novo mutations in ASD by sequencing the exomes of ASD cases and their parents (n= 175 trios). Fewer than half of the cases (46.3%) carry a missense or nonsense de novo variant and the overall rate of mutation is only modestly higher than the expected rate. In contrast, there is significantly enriched connectivity among the proteins encoded by genes harboring de novo missense or nonsense mutations, and excess connectivity to prior ASD genes of major effect, suggesting a subset of observed events are relevant to ASD risk. The small increase in rate of de novo events, when taken together with the connections among the proteins themselves and to ASD, are consistent with an important but limited role for de novo point mutations, similar to that documented for de novo copy number variants. Genetic models incorporating these data suggest that the majority of observed de novo events are unconnected to ASD, those that do confer risk are distributed across many genes and are incompletely penetrant (i.e., not necessarily causal). Our results support polygenic models in which spontaneous coding mutations in any of a large number of genes increases risk by 5 to 20-fold. Despite the challenge posed by such models, results from de novo events and a large parallel case-control study provide strong evidence in favor of CHD8 and KATNAL2 as genuine autism risk factors.
doi:10.1038/nature11011
PMCID: PMC3613847  PMID: 22495311
8.  AnnTools: a comprehensive and versatile annotation toolkit for genomic variants 
Bioinformatics  2012;28(5):724-725.
Summary: AnnTools is a versatile bioinformatics application designed for comprehensive annotation of a full spectrum of human genome variation: novel and known single-nucleotide substitutions (SNP/SNV), short insertions/deletions (INDEL) and structural variants/copy number variation (SV/CNV). The variants are interpreted by interrogating data compiled from 15 constantly updated sources. In addition to detailed functional characterization of the coding variants, AnnTools searches for overlaps with regulatory elements, disease/trait associated loci, known segmental duplications and artifact prone regions, thereby offering an integrated and comprehensive analysis of genomic data. The tool conveniently accepts user-provided tracks for custom annotation and offers flexibility in input data formats. The output is generated in the universal Variant Call Format. High annotation speed makes AnnTools suitable for high-throughput sequencing facilities, while a low-memory footprint and modest CPU requirements allow it to operate on a personal computer. The application is freely available for public use; the package includes installation scripts and a set of helper tools.
Availability: http://anntools.sourceforge.net/
Contact: vladimir.makarov@mssm.edu; chris.yoon@mssm.edu
Supplementary information: Supplementary data are available at Bioinformatics online.
doi:10.1093/bioinformatics/bts032
PMCID: PMC3289923  PMID: 22257670
9.  Mutation Screening of the PTEN Gene in Patients With Autism Spectrum Disorders and Macrocephaly 
American Journal of Medical Genetics  2007;144B(4):484-491.
Mutations in the PTEN gene are associated with a broad spectrum of disorders, including Cowden syndrome (CS), Bannayan–Riley–Ruvalcaba syndrome, Proteus syndrome, and Lhermitte–Duclos disease. In addition, PTENmutations have been described in a few patients with autism spectrum disorders (ASDs) and macrocephaly. In this study, we screened the PTEN gene for mutations and deletions in 88 patients with ASDs and macrocephaly (defined as ≥2 SD above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions, as well as the promoter region. Dosage analysis of PTEN was carried out using multiplex ligation-dependent probe amplification (MLPA). No partial or whole gene deletions were observed. We identified a de novo missense mutation (D326N) in a highly conserved amino acid in a 5-year-old boy with autism, mental retardation, language delay, extreme macrocephaly (+9.6 SD) and polydactyly of both feet. Polydactyly has previously been described in two patients with Lhermitte–Duclos disease and CS and is thus likely to be a rare sign of PTEN mutations. Our findings suggest that PTEN mutations are a relatively infrequent cause of ASDs with macrocephaly. Screening of PTEN mutations is warranted in patients with autism and pronounced macrocephaly, even in the absence of other features of PTEN-related tumor syndromes.
doi:10.1002/ajmg.b.30493
PMCID: PMC3381648  PMID: 17427195
Cowden syndrome; Bannayan–Riley–Ruvalcaba syndrome; polydactyly; sequence analysis; multiplex ligation-dependent probe amplification
10.  Genetic Markers for PTSD Risk and Resilience Among Survivors of the World Trade Center Attacks 
Disease markers  2011;30(2-3):101-110.
We have previously reported the differential expression of 17 probe sets in survivors of the 9/11 attacks with current posttraumatic stress disorder (PTSD) compared to similarly exposed survivors with no lifetime PTSD. The current study presents an expanded analysis of these subjects, including genotype at FKBP5, a modulator of glucocorticoid receptor (GR) sensitivity. It includes data from additional subjects who developed PTSD following 9/11 but then recovered, distinguishing expression profiles associated with risk for developing PTSD, resilience, and symptom recovery. 40 Caucasians (20 with and 20 without PTSD, matched for exposure, age, and gender) were selected from a population-representative sample of persons exposed to the 9/11 attacks from which longitudinal data had been collected in four previous waves. Whole blood gene expression and cortisol levels were obtained and genome-wide gene expression was analyzed. 25 probe sets were differentially expressed in PTSD. Identified genes were generally involved in hypothalamic-pituitary-adrenal axis, signal transduction, or in brain and immune cell function. STAT5B, a direct inhibitor of GR, and nuclear factor I/A, both showed reduced expression in PTSD. Comparison of lifetime versus current PTSD identified overlapping genes with altered expression suggesting enduring markers, while some markers present only in current PTSD may reflect state measures. As a follow-up, direct comparisons of expression in current PTSD, lifetime-only PTSD, and control groups identified FKBP5 and MHC Class II as state markers, and also identified several trait markers. An analysis of indirect effects revealed that homozygosity for any of 4 PTSD risk-related polymorphisms at FKBP5 predicted FKBP5 expression, which mediated indirect effects of genotype on plasma cortisol and PTSD severity.
doi:10.3233/DMA-2011-0764
PMCID: PMC3825240  PMID: 21508514
Stress disorders; post-traumatic; gene expression; genotype; FKBP5 protein; human; cortisol; September 11 terrorist attacks; childhood trauma
11.  Dementia Revealed: Novel Chromosome 6 Locus for Late-Onset Alzheimer Disease Provides Genetic Evidence for Folate-Pathway Abnormalities 
PLoS Genetics  2010;6(9):e1001130.
Genome-wide association studies (GWAS) of late-onset Alzheimer disease (LOAD) have consistently observed strong evidence of association with polymorphisms in APOE. However, until recently, variants at few other loci with statistically significant associations have replicated across studies. The present study combines data on 483,399 single nucleotide polymorphisms (SNPs) from a previously reported GWAS of 492 LOAD cases and 496 controls and from an independent set of 439 LOAD cases and 608 controls to strengthen power to identify novel genetic association signals. Associations exceeding the experiment-wide significance threshold () were replicated in an additional 1,338 cases and 2,003 controls. As expected, these analyses unequivocally confirmed APOE's risk effect (rs2075650, ). Additionally, the SNP rs11754661 at 151.2 Mb of chromosome 6q25.1 in the gene MTHFD1L (which encodes the methylenetetrahydrofolate dehydrogenase (NADP+ dependent) 1-like protein) was significantly associated with LOAD (; Bonferroni-corrected P = 0.022). Subsequent genotyping of SNPs in high linkage disequilibrium () with rs11754661 identified statistically significant associations in multiple SNPs (rs803424, P = 0.016; rs2073067, P = 0.03; rs2072064, P = 0.035), reducing the likelihood of association due to genotyping error. In the replication case-control set, we observed an association of rs11754661 in the same direction as the previous association at P = 0.002 ( in combined analysis of discovery and replication sets), with associations of similar statistical significance at several adjacent SNPs (rs17349743, P = 0.005; rs803422, P = 0.004). In summary, we observed and replicated a novel statistically significant association in MTHFD1L, a gene involved in the tetrahydrofolate synthesis pathway. This finding is noteworthy, as MTHFD1L may play a role in the generation of methionine from homocysteine and influence homocysteine-related pathways and as levels of homocysteine are a significant risk factor for LOAD development.
Author Summary
Studies looking for genetic variants across the genome that affect late-onset Alzheimer disease (LOAD) have had little success identifying genes other than APOE. Here, we use an expanded set of AD cases and controls to improve our power to detect genetic variants driving LOAD risk. Analyzing 483,399 genetic variants across the genome in a discovery dataset of 931 cases and 1,104 controls, we found a strong association to the marker rs11754661 on chromosome 6 in the gene MTHFD1L, in addition to the highly replicated chromosome 19 APOE association. We genotyped adjacent variants on chromosome 6 in these same cases and controls and found these variants were also associated with LOAD. We replicated the association with rs11754661 and additional SNPs in MTHFD1L in a combined dataset of cases and controls from our laboratory and from publicly available datasets. This finding is important because the gene is known to be involved in biological pathways influencing levels of homocysteine, a significant risk factor for AD.
doi:10.1371/journal.pgen.1001130
PMCID: PMC2944795  PMID: 20885792
12.  Autism genome-wide copy number variation reveals ubiquitin and neuronal genes 
Nature  2009;459(7246):569-573.
Autism spectrum disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins1–4. Previous studies focusing on candidate genes or genomic regions have identified several copy number variations (CNVs) that are associated with an increased risk of ASDs5–9. Here we present the results from a whole-genome CNV study on a cohort of 859 ASD cases and 1,409 healthy children of European ancestry who were genotyped with ~550,000 single nucleotide polymorphism markers, in an attempt to comprehensively identify CNVs conferring susceptibility to ASDs. Positive findings were evaluated in an independent cohort of 1,336 ASD cases and 1,110 controls of European ancestry. Besides previously reported ASD candidate genes, such as NRXN1 (ref. 10) and CNTN4 (refs 11, 12), several new susceptibility genes encoding neuronal cell-adhesion molecules, including NLGN1 and ASTN2, were enriched with CNVs in ASD cases compared to controls (P = 9.5 × 10−3). Furthermore, CNVs within or surrounding genes involved in the ubiquitin pathways, including UBE3A, PARK2, RFWD2 and FBXO40, were affected by CNVs not observed in controls (P = 3.3 × 10−3). We also identified duplications 55 kilobases upstream of complementary DNA AK123120 (P = 3.6 × 10−6). Although these variants may be individually rare, they target genes involved in neuronal cell-adhesion or ubiquitin degradation, indicating that these two important gene networks expressed within the central nervous system may contribute to the genetic susceptibility of ASD.
doi:10.1038/nature07953
PMCID: PMC2925224  PMID: 19404257
13.  A large-scale screen for coding variants in SERT/SLC6A4 in autism spectrum disorders 
In the current study we explored the hypothesis that rare variants in SLC6A4 contribute to autism susceptibility and to rigid-compulsive behaviors in autism. We made use of a large number of unrelated cases with autism spectrum disorders (∼350) and controls (∼420) and screened for rare exonic variants in SLC6A4 by a high-throughput method followed by sequencing. We observed no difference in the frequency of such variants in the two groups. Furthermore, we did not observe an association of rare coding variants in SLC6A4 with rigid-compulsive traits scores in the cases. These results do not support a significant role for rare coding variants in SLC6A4 in autism spectrum disorders, nor do they support a significant role for SLC6A4 in rigid-compulsive traits in these disorders.
doi:10.1002/aur.30
PMCID: PMC2678895  PMID: 19360675
14.  Multiplex ligation-dependent probe amplification for genetic screening in autism spectrum disorders: Efficient identification of known microduplications and identification of a novel microduplication in ASMT 
BMC Medical Genomics  2008;1:50.
Background
It has previously been shown that specific microdeletions and microduplications, many of which also associated with cognitive impairment (CI), can present with autism spectrum disorders (ASDs). Multiplex ligation-dependent probe amplification (MLPA) represents an efficient method to screen for such recurrent microdeletions and microduplications.
Methods
In the current study, a total of 279 unrelated subjects ascertained for ASDs were screened for genomic disorders associated with CI using MLPA. Fluorescence in situ hybridization (FISH), quantitative polymerase chain reaction (Q-PCR) and/or direct DNA sequencing were used to validate potential microdeletions and microduplications. Methylation-sensitive MLPA was used to characterize individuals with duplications in the Prader-Willi/Angelman (PWA) region.
Results
MLPA showed two subjects with typical ASD-associated interstitial duplications of the 15q11-q13 PWA region of maternal origin. Two additional subjects showed smaller, de novo duplications of the PWA region that had not been previously characterized. Genes in these two novel duplications include GABRB3 and ATP10A in one case, and MKRN3, MAGEL2 and NDN in the other. In addition, two subjects showed duplications of the 22q11/DiGeorge syndrome region. One individual was found to carry a 12 kb deletion in one copy of the ASPA gene on 17p13, which when mutated in both alleles leads to Canavan disease. Two subjects showed partial duplication of the TM4SF2 gene on Xp11.4, previously implicated in X-linked non-specific mental retardation, but in our subsequent analyses such variants were also found in controls. A partial duplication in the ASMT gene, located in the pseudoautosomal region 1 (PAR1) of the sex chromosomes and previously suggested to be involved in ASD susceptibility, was observed in 6–7% of the cases but in only 2% of controls (P = 0.003).
Conclusion
MLPA proves to be an efficient method to screen for chromosomal abnormalities. We identified duplications in 15q11-q13 and in 22q11, including new de novo small duplications, as likely contributing to ASD in the current sample by increasing liability and/or exacerbating symptoms. Our data indicate that duplications in TM4SF2 are not associated with the phenotype given their presence in controls. The results in PAR1/PAR2 are the first large-scale studies of gene dosage in these regions, and the findings at the ASMT locus indicate that further studies of the duplication of the ASMT gene are needed in order to gain insight into its potential involvement in ASD. Our studies also identify some limitations of MLPA, where single base changes in probe binding sequences alter results. In summary, our studies indicate that MLPA, with a focus on accepted medical genetic conditions, may be an inexpensive method for detection of microdeletions and microduplications in ASD patients for purposes of genetic counselling if MLPA-identified deletions are validated by additional methods.
doi:10.1186/1755-8794-1-50
PMCID: PMC2588447  PMID: 18925931
15.  Mutation analysis of the NSD1 gene in patients with autism spectrum disorders and macrocephaly 
BMC Medical Genetics  2007;8:68.
Background
Sotos syndrome is an overgrowth syndrome characterized by macrocephaly, advanced bone age, characteristic facial features, and learning disabilities, caused by mutations or deletions of the NSD1 gene, located at 5q35. Sotos syndrome has been described in a number of patients with autism spectrum disorders, suggesting that NSD1 could be involved in other cases of autism and macrocephaly.
Methods
We screened the NSD1 gene for mutations and deletions in 88 patients with autism spectrum disorders and macrocephaly (head circumference 2 standard deviations or more above the mean). Mutation analysis was performed by direct sequencing of all exons and flanking regions. Dosage analysis of NSD1 was carried out using multiplex ligation-dependent probe amplification.
Results
We identified three missense variants (R604L, S822C and E1499G) in one patient each, but none is within a functional domain. In addition, segregation analysis showed that all variants were inherited from healthy parents and in two cases were also present in unaffected siblings, indicating that they are probably nonpathogenic. No partial or whole gene deletions/duplications were observed.
Conclusion
Our findings suggest that Sotos syndrome is a rare cause of autism spectrum disorders and that screening for NSD1 mutations and deletions in patients with autism and macrocephaly is not warranted in the absence of other features of Sotos syndrome.
doi:10.1186/1471-2350-8-68
PMCID: PMC2248565  PMID: 18001468

Results 1-15 (15)