In linear regression analyses with ACFS as the dependent variable, we first confirmed that a history of CSA is associated with higher lifetime alcohol consumption (main effect for CSA, p<0.003). We performed a similar analysis and found no significant main effect for H2 haplotype (p>0.77). We then examined whether a G × E interaction involving CSA and H2 haplotype was observed in analyses that also included terms for main effects of CSA, gender, and H2 haplotype. We found a significant G × E interaction with the H2 haplotype protecting against CSA-associated effects on alcohol consumption (see TABLE 2). To demonstrate the protective effects of the G × E interaction more clearly, we compared mean ACFS by CSA and H2 haplotype status. We initially confirmed that mean ACFS did not vary by gender for either H1 homozygotes (p>0.69) or individuals with the H2 haplotype (p>0.88). We then found that significantly higher (p=0.0006) mean ACFS was associated with a history of CSA only in H1 homozygotes; in individuals with the H2 haplotype, the mean ACFS varied minimally (p=0.77) with CSA status (FIGURE 2).
