As expected from the extensive literature, we observed that subjects with higher Impulsiveness scores also had higher percentage of alcohol dependence symptoms, replicating the established evidence of the relationship between Impulsiveness and alcoholism 28, 47, 49. We also replicate the association of two GABRA2 SNPs and the haplotype with the presence of alcoholic symptoms. A large number of subjects in this study do not have any alcoholic symptom resulting in an excessive number of zeroes (240/448) for which a Zero-inflated Poisson test was applied. Subjects with the GG allele for both SNPs and haplotype are more likely to have any alcoholic symptom compared to A carriers. Several studies have reported the association of GABRA2 variants and alcohol-related traits but the direction of the association is not consistent. Two major haplotypes have been identified for this high-LD region. The haplotype containing the G allele for both SNPs analyzed in this study, has been associated with alcohol dependence in four studies 5, 6, 8, 9 and with the complementary haplotype (the A allele from both SNPs) in three studies 3, 11, 12.
