The frequency of OPRK1 G36T and OPRM1 A118G opioid receptor gene polymorphisms in heroin-dependent individuals and non-dependent healthy subjects in Turkey

Objective: Polymorphisms of the Mu opioid receptor (MOR) gene (OPRM1), which encodes for the primary action site of heroin, have also been found to be associated with heroin addiction. The aim of this study was to investigate the relationships between heroin addiction and G36T OPRK1 and A118G OPRM1 receptor gene polymorphisms in a male population in Turkey. Method: 102 male patients with heroin use (without any other drug use) and 82 subjects without any history of opioid use were evaluated. The A118G and G36T SNPs on the MOR and Kappa opioid receptors (KOR) genes were assessed via TaqMan 5’-exonuclease allelic discrimination assays. Results: The mean duration of heroin use was 4.6±1.9 years. The G36T polymorphism and heterozygous genotype were both found to be more frequent in the patient group (OPRK1 gene). In the patient group, 79 (77.5%) patients had wild-type genotype and 23 (22.5%) patients had mutant genotype. In the control group, 76 (92.7 %) subjects had wild-type genotype and 6 (7.3 %) subjects had mutant genotype (p=0.005). Wild type allele frequency was determined to be 0.894 and mutant type allele frequency was 0.105. With regard to the A118G polymorphism, we found that there was no difference between groups in terms of genotype. Discussion: Our findings support a considerable role for OPRK1 in opioid addiction; however, in conflict with most studies, we did not determine a relationship with A118G in Turkish subjects. We suggest that further stu-dies should be conducted to ascertain the clinical implications of opioid gene polymorphisms in Turkey.