These results provide further support suggesting that rs3778150 may be causally related to substance use phenotypes, including alcohol use, and could potentially account for previously observed associations of rs1799971 with substance use phenotypes. Furthermore, these findings provide additional clarification regarding the role of OPRM1 and rs1799971. Future studies should investigate potential causal relations among genetic variants in OPRM1, subjective response to alcohol, and drinking phenotypes to further delineate the associations of rs3778150 with alcohol use and dependence.
