A total of 167 families were ascertained for the study if at least one child between the ages of 5 and 12 years met enrollment criteria. A detailed description of the study population is provided in Table 2. Families were enrolled if the proband: (i) met DSM-IV criteria for AD/HD, (ii) was not home-schooled (so that parent and teacher informants were independent), (iii) had a full scale IQ estimate greater than 70 as determined by the Wechsler Intelligence Scale for Children, Fourth Edition intelligence test vocabulary and block design subtest scores (individuals who scored between 70 and 80 had to score greater than 70 on the Vineland Adaptive Behavior Scale Adaptive Behavior Composite Score), and (iv) had Clinical Global Impressions Scale Severity Scores ≥3. Families were excluded from the study if the child: (i) was not the biological child of the primary caregiver, (ii) was diagnosed with a pervasive developmental disorder, (iii) displayed significant signs of developmental delay, or (iv) had a coexisting medical, neurological, or genetic disorder. Families were ascertained from two collection sites: Duke University Medical Center, North
