The current results are also of interest from a practical perspective in light of studies of pharmacotherapy for ADHD that have focused on the role of the DRD4 genotype in predicting response to treatment. These studies have found preferential response to treatment among youth with the 4-repeat genotype compared with those carrying the 7-repeat allele (e.g. Cheon, Kim, & Cho, 2007; Hamarman, Fossella, Ulger, Brimacombe, & Dermody, 2004). Combined with the present results and those of Bakermans-Kranenburg et al. (2008), this suggests the intriguing possibility of differential effectiveness of various intervention modalities for some problems in childhood and early adolescence as a function of genotype or associated behavioral characteristics (i.e., pharmacological intervention for some allelic variants or phenotypes and psychosocial interventions for others). Although additional research is necessary, youths with the 7-repeat allele may be particularly responsive to parenting-based intervention whereas those with two 4-repeat alleles are not. This may provide opportunities to enhance universal, community-based interventions by making special efforts to recruit those most likely to show the greatest response. Likewise, the current results suggest that caregivers of some
