As shown in Model III, there was a significant interaction between gender and genotype (p < 0.05) such that carrying the high-risk genotype on GABRA2 had no significant effect on the odds of alcohol dependence among women (OR = 0.94), but was associated with a substantial increase in odds among men (OR = 1.83, p < 0.001). The predicted probability of alcohol dependence for men with the low-risk genotype was 0.46, compared to 0.61 for men with the high-risk genotype (Z = 3.54, p < 0.01)—a change in predicted probability of 0.15. In contrast, the predicted probability of alcohol dependence for women was 0.17 for those with the low-risk genotype and 0.18 for those with the high-risk genotype. This pattern was very similar in the subsample that excluded probands with alcohol dependence; the change in predicted probability of alcohol dependence associated with genotype for men was 0.13 (Z = 3.02, p < 0.01) and there was no change for women.
