Technologies, Thermo Fisher)]. For the remaining 6% of participants, the GABRA2 rs279845 genotype could not be determined based on the DNA samples provided. The 1,920 youth successfully genotyped for GABRA2 rs279845 make up the analytic sample of the current study (40% male, 53% intervention condition, 66% Cohort 2; 90% non-Hispanic White, 4% Hispanic, 2% African-American, <1% Native American, 1% Asian, 2% Other). GABRA2 genotype frequencies (21% AA, 49% AT, 30% TT) were in Hardy-Weinberg Equilibrium (χ2(df=2)=0.06, p=.97), consistent with population estimates (see dbSNP, http://www.ncbi.nlm.nih.gov/snp and the 1000 genomes project, http://www.1000genomes.org/). The genotype distribution did not differ by intervention condition, χ2(df=2)=0.28, p=.87, self-reported White versus non-White race/ethnicity, χ2(df=2)=2.23, p=.33, or White versus non-White race/ethnicity identified via ancestry informative genetic markers (see description in Statistical Analysis section), χ2(df=2)=1.60, p=.45; however, the distribution did differ by gender, χ2(df=2)=9.48, p=.009. Follow-up analyses showed male genotype frequencies (24% AA, 50% AT, 27% TT) differed from females (19% AA, 49% AT, 32% TT), but only for the two homozygotes (ps <.014).
