To illustrate the recent drinking history x genotype interaction observed for the GABRA2 SNP, a median split (median = 4.6 drinks/drinking day) was used to assign subjects to either a higher or lower recent drinking history group. As shown in Figure 5, all groups had negative average PC1 scores, indicating acute tolerance to the subjective effects of alcohol that comprise PC1, but they differed in degree. In the higher recent drinking history group, individuals with the CC genotype showed the least acute tolerance and individuals with the TT genotype showed the greatest acute tolerance. In the lower recent drinking history group, the opposite was observed: individuals with the CC genotype displayed the greatest acute tolerance while subjects with the TT genotype displayed less tolerance. Individuals with the CT genotype displayed intermediate PC1 values in the higher drinking group, and resembled TT individuals in the lower drinking group.
