To ensure that subsequent findings related to ADHD rather than comorbid intellectual disability, we restricted genome-wide locus-specific tests to participants without intellectual disability. A locus on chromosome 16p13.11 (chr16:15156431-18174650) showed a significant excess of rare CNVs larger than 500 kb in children with ADHD (p=0·0008 corrected for multiple testing of all CNV loci by permutation; OR 13·88, 95% CI 2·3–82·2). Post-hoc analysis revealed that the excess of CNVs at this locus was due to duplications (corrected p=0·0001), which spanned an 824 kb consensus region (chr16:15 385 551–16 209 503; figure 2). Analysis of DNA from both parents for two ADHD probands carrying 16p13.11 duplications revealed one to be maternally inherited and the other to be de novo (webappendix p 2). No duplications in this region were identified in our control sample. This consensus region is flanked by segmental duplications, spans only seven genes, and has been implicated in schizophrenia.22
