Attention deficit hyperactivity disorder (ADHD) is a common, heritable neuropsychiatric disorder of unknown etiology. We performed a whole-genome copy number variation (CNV) study on 1,013 cases with ADHD and 4,105 healthy children of European ancestry using 550,000 SNPs. We evaluated statistically significant findings in multiple independent cohorts, with a total of 2,493 cases with ADHD and 9,222 controls of European ancestry, using matched platforms. CNVs affecting metabotropic glutamate receptor genes were enriched across all cohorts (P = 2.1 × 10−9). We saw GRM5 (encoding glutamate receptor, metabotropic 5) deletions in ten cases and one control (P = 1.36 × 10−6). We saw GRM7 deletions in six cases, and we saw GRM8 deletions in eight cases and no controls. GRM1 was duplicated in eight cases. We experimentally validated the observed variants using quantitative RT-PCR. A gene network analysis showed that genes interacting with the genes in the GRM family are enriched for CNVs in ∼10% of the cases (P = 4.38 × 10−10) after correction for occurrence in the controls. We identified rare recurrent CNVs affecting glutamatergic neurotransmission genes that were overrepresented in multiple ADHD cohorts.
Access optionsAccess options
Subscribe to Journal
Get full journal access for 1 year
only $18.75 per issue
All prices are NET prices.
VAT will be added later in the checkout.
Rent or Buy article
Get time limited or full article access on ReadCube.
All prices are NET prices.
We thank all the children with ADHD and their families who participated in this study and all the control subjects who donated blood samples to The Children's Hospital of Philadelphia (CHOP) for genetic research purposes. We thank the technical staff at the Center for Applied Genomics, CHOP for generating the genotypes used in this study and the medical assistants, and nursing and medical staff who recruited the subjects. We thank the Center for Biomedical Informatics for bioinformatics support. We also thank S. Kristinsson, L.A. Hermannsson and A. Krisbjörnsson for their software design and contribution to the study.
We thank the IMAGE, IMAGE II and PUWMa consortium investigators and the NIMH for making the genotype data available. Funding support for International Multi-Center ADHD Genetics (IMAGE) and IMAGE II Projects was provided by US National Institutes of Health (NIH) grant R01MH62873 to S.V.F., and the genotyping of samples was provided through the Genetic Association Information Network (GAIN). The dataset used for the IMAGE analyses described in this manuscript were obtained from the database of Genotype and Phenotype (dbGaP), which is found at http://www.ncbi.nlm.nih.gov/gap, through dbGaP accession numbers phs000016.v2.p2 (ADHD IMAGE), phs000020.v2.p1 (depression) and phs000019.v1.p1 (psoriasis). Samples and associated phenotype data for the GAIN Major Depression: Stage 1 Genome-wide Association In Population Based Samples Study (principal investigator, P.F. Sullivan, University of North Carolina) were provided by D.I. Boomsma and E. de Geus, Vrije Universiteit Amsterdam (principal investigators, Netherlands Twin Register); B.W. Penninx, Vrije Universiteit Medical Center Amsterdam; F. Zitman, Leiden University Medical Center, Leiden; and W. Nolen, University Medical Center Groningen (principal investigators and site principal investigators, Netherlands Study of Depression and Anxiety). Samples and associated phenotype data for the Collaborative Association Study of Psoriasis were provided by J.T. Elder (University of Michigan, Ann Arbor, Michigan), G.G. Krueger (University of Utah, Salt Lake City, Utah), A. Bowcock (Washington University, St. Louis, Missouri) and G.R. Abecasis (University of Michigan, Ann Arbor, Michigan). Samples and associated phenotype data for the International Multi-Center ADHD Genetics Project were provided by the following investigators: S.V.F. (principal investigator), R.J.L.A., P.A., J.S., R.P.E., B.F., M. Gill, A. Miranda, F. Mulas, R.D.O., H.R., A. Rothenberger, T.B., J. Buitelaar, E. Sonuga-Barke and H.-C.S. (site principal investigators), M. Daly, C. Lange, N. Laird, J. Su and B. Neale (statistical analysis team). Samples and associated phenotype data were accessed through an authorized data access request by H.H. and S.F.A.G. Data collection for the PUWMa sample was supported by NIH grants to S.V.F., J. Biederman, S. Smalley, R. Todd and A.A.T. GWAS genotyping of the PUWMa samples was completed by Genizon and was provided through a grant for genotyping services to S.V.F. The PUWMa consortium represents a Pfizer-funded collaboration among the University of California Los Angeles, Washington University and Massachussetts General Hospital. We thank M.C. O'Donovan, M. Gill, M.J. Owen, P.A. Holmans, A. Thapar, B.M. Neale and A. Miranda for contributing DNA samples and phenotypes to the study and for editing the manuscript. We thank G. DePalma, T. Töpner, A. Guiney and H. Zhang for providing samples for the qRT-PCR CNV validation.
The study was supported by an Institutional Development Award to the Center for Applied Genomics from CHOP (H.H.), which funded all of the discovery genome-wide genotyping for this study. This work was additionally supported in part by NIH grant K23MH066275 (J.E.), University of Pennsylvania National Center for Research Resources Clinical and Translational Science Awards grant UL1-RR-024134 (J.E.), by a Research Development Award from the Cotswold Foundation (H.H. and S.F.A.G.) and by US Department of Health and Human Services grant 1RC2MH089924 (H.H.). N.T., T.S. and J.D.B. received support from the Seaver Foundation and a Conte Center for Neuroscience of Mental Disorders grant from the NIMH (P50MH066392).
Sample and phenotype data collection of parts of the IMAGE II cohort was supported by the Deutsche Forschungsgemeinschaft (KFO 125, SFB 581 and SFB TRR 58 to K.-P.L. and A. Reif, ME 1923/5-1 and ME 1923/5-3 to C.M.F. and J.M.) and the Bundesministerium für Bildung und Forschung (BMBF 01GV0605 to K.-P.L.).
Supplementary Note, Supplementary Figures 1–11 and Supplementary Tables 1–17.