Association between mu opioid receptor gene polymorphisms and Chinese heroin addicts.

Mu opioid receptor (MOR) has been shown to be associated with alcoholism and opioid dependence. The present study examined the involvement of a polymorphism in A118G in exon 1 and C1031G in intron 2 of the MOR gene in 200 Chinese heroin-dependent and 97 control subjects. Results showed a significant association for both A118G and C1031G polymorphisms and opioid dependence. The G allele is more common in the heroin-dependent group (39.5% and 30.8% for A118G and C1031G polymorphisms, respectively) when compared to the controls (29.4% and 21.1% for A118G and C1031G polymorphisms, respectively). This study suggests that the variant G allele of both A118G and C1031G polymorphisms may contribute to the vulnerability to heroin dependence.