Table 2 presents p-values from the association tests with the externalizing behavior measures: clinical symptom counts and the Achenbach Externalizing scale. Table 3 presents p-values from the association tests with the various personality scales measuring domains of impulsivity. The pattern of results is striking: there is no association between GABRA2 and clinical symptoms of any of the externalizing disorders in either the young adult or adolescent sample (there is one p < .05 with alcohol-dependence symptoms in the adult sample, but this is not replicated in the other correlated SNPs). There is, however, association with the Achenbach Externalizing scale scores across both samples. A joint analysis of externalizing across both samples yields a minimum p = .0003. Furthermore, in the adolescent sample, an association is observed across all SNPs with SSS and NEO Extraversion (Table 3). Two SNPs also yield p < .05 in the adolescent sample with conscientiousness, but no single SNP is less than the Nyholt-corrected p-value of 0.026, suggesting this association should be viewed more tentatively. The association with these personality measures is not observed in the
