Attention-deficit/hyperactivity disorder families were recruited from pediatric and behavioral health clinics in the Philadelphia area. Inclusion criteria included families of European descent with an ADHD proband (age 6–18). Exclusionary criteria included prematurity (<36 weeks), mental retardation, major medical and neurological disorders, pervasive developmental disorder, psychoses and major mood disorders. Blood collected from ADHD families was sent to the Rutgers University Cell and DNA Repository in New Jersey where lymphoblastoid cell lines were developed. Subsequently, DNA was extracted and returned to our laboratory for genotyping.
