To explore the presence of population-specific effects of rs7916403, association analyses were conducted on the European-American subset, the largest ethnic group in the study samples. For the GWAS sample (N = 771), the association between theta EROs and rs7916403 (P = 9.97 × 10−4) is stronger than what was observed for the total GWAS, with a β coefficient of −0.18 [95% CI: −0.073 – −0.29] in the direction of the G allele. For European-Americans in the family-based replication sample (N = 862), the HTR7 risk allele (G) was also found to be significantly associated with theta ERO (P = 0.025), with a genetic effect of −0.12 [95% CI: −0.11 – −0.22]. Additionally, diagnoses for alcohol dependence were examined separately for European-Americans, revealing a significant OR of 1.27 [95% CI: 1.06 – 1.52] for the G allele in the GWAS subset (P = 0.011). When testing rs7916403 under a recessive mode of genetic effect, an increased OR of 1.39 [95% CI: 1.07 – 1.81] was observed (P = 0.015). For the replication sample, no significant evidence of association with alcohol dependence
