The present study examines genetic variation in the A118G SNP (rs17799971) of the mu opioid receptor (OPRM1) gene as a moderator of neural responses to alcohol cues and of dorsal and ventral striatal functional connectivity during an alcohol taste cues task. This SNP is thought to increase receptor binding affinity for β-endorphin by three-fold (Bond et al., 1998). Further, the G allele is associated with deleterious effects on both mRNA and OPRM1 protein yield (Zhang et al., 2005). Experimental studies found that G-allele carriers report greater subjective reinforcement from alcohol in the laboratory (Ray and Hutchison, 2004) and in the natural environment (Ray et al., 2010). Among heavy drinkers, the G allele was associated with greater hemodynamic response to alcohol cues in mesocorticolimbic areas (Filbey et al., 2008b) and greater striatal dopamine release following acute alcohol administration (Ramchandani et al., 2011). This study extends the literature to alcohol dependent individuals. The present study also differs from Filbey et al. (2008b) by evaluating functional connectivity during an alcohol cue exposure task.
