We selected two genes, DOCK3 and SLC9A9, to be evaluated in an AD/HD family-based association study. After adjusting for multiple testing, we identified a 3′UTR SNP (rs1046706) in SLC9A9 that was significantly associated with scores on the DSM-IV hyperactive-impulsive and total symptom subscales according to the CTRS, and the CPT measure, errors of commission. Although the following findings did not withstand correction for multiple testing, the 3′UTR SNP was also nominally associated with five additional AD/HD measures suggesting that our association finding is consistent across multiple measures of impulsivity and, to a lesser extent, inattentiveness. We do not find it particularly surprising that the 3′UTR SNP remained significantly associated with the Conners’ scores according to teacher ratings, but not parent ratings given the lower heritability estimates for those measures in our study population and the fact that multiple studies have shown that informant ratings are often discordant [reviewed in Ref. (De Los and Kazdin, 2005)]. Nonetheless, we are encouraged to find that rs1046706 showed nominal associations with hyperactive-impulsive, inattentive, and total symptom subscales according to the CPRS. Interestingly, this 3′UTR
