Dopamine risk and paternal ADHD symptomatology associated with ADHD symptoms in four and a half-year-old boys.

Results There were main effects for DAT1 and father symptomatology for the child Total ADHD and Hyperactivity–Impulsivity scores. The main effects for DRD4 were limited to the child Hyperactivity–Impulsivity scores. Child Inattentive scores were influenced only by father symptomatology. Interaction effects between DAT1 and DRD4 and between DAT1 and the father ADHD risk group were found for child Hyperactivity–Impulsivity scores. Boys with the highest level of symptomatology were those with the 10/10 DAT1 genotype and the DRD4-7 genotype or fathers with high symptomatology.