The µ-opioid receptor nonsynonymous variant 118A>G is associated with prolonged abstinence from heroin without agonist treatment.

ABSTRACT

AIM: This study assesses whether opioid-related gene variants contribute to reduced vulnerability to relapse to heroin in persons who are not treated with µ-opioid receptor agonist. METHODS: Genotypes of 71 SNPs, in nine genes, were analyzed for association with long-term abstinence in former heroin-dependents of European/Middle Eastern ancestry, either without agonist treatment (n = 129) or in methadone maintenance treatment (n = 922). RESULTS: The functional OPRM1 nonsynonymous SNP rs1799971 (118A>G) showed significant association with long-term abstinence (Ppermutation  = 0.03, dominant model, OR 2.2; 95% CI 1.5-3.3). CONCLUSION: Since the stress axis is regulated in part by ß-endorphin, this functional OPRM1 SNP may blunt the endogenous stress response and contribute to reduced vulnerability for relapse.