The ADHD patient sample consisted of 799 Caucasian children from Cardiff, Wales (N=559); St. Andrews, Scotland (N=44); and Dublin, Ireland (N=196). All children were recruited from community clinics and met DSM-IV or ICD-10 criteria for ADHD or hyperkinetic disorder. To be comparable with other GWAS, we excluded children with a major medical or neurological condition (including epilepsy), autism, bipolar disorder, or intellectual disability (IQ <70).
