To investigate CNVs in ADHD, we studied a UK sample of carefully phenotyped children with ADHD and unrelated ethnically matched controls. Our first aim was to examine whether children with ADHD had an increased burden of CNVs compared with controls, and to test whether this increase was attributable to associated intellectual disability since ADHD, similarly to autism and schizophrenia, occurs with increased frequency in individuals with intellectual disability (IQ test score <70).13–15 Our second aim was to investigate whether identified CNVs in our ADHD sample were significantly enriched for a specific chromosomal locus or loci previously implicated in autism and schizophrenia.
