Dopamine gene variants in opioid addiction: comparison of dependent patients, nondependent users and healthy controls

To determine whether specific dopaminergic system gene variants are associated with opioid dependence. Subjects included 153 healthy controls, 163 opioid exposed, but not dependent and 281 opioid dependent. Genotypes of 90 variants in 13 genes were examined. The most significant results were obtained for DA β-hydroxylase variants, rs2073837 and rs1611131, which were associated with protection from addiction (q = 0.0172, 0.0415, respectively) and the functional TH variant, rs2070762, was associated with more risk (q = 0.0387). The three variants also showed a combined effect that remained significant after correction for multiple testing (pfinal = 0.0039). These data offer support that dopaminergic gene variants have a role in opioid dependence and warrant further study