No association between GSTM1 and GSTT1 genetic polymorphisms and susceptibility to opium sap dependence

Glutathione S-transferases (GSTs; EC: 2.5.1.18) are a ubiquitous family of eukaryotic and prokaryotic phase II metabolic isozymes. Genes encoding GSTM1 (OMIM: 138350), and GSTT1 (OMIM: 600436) are members of class mu and theta, respectively. The most common polymorphism in the GSTM1 is a deletion of the whole GSTM1 gene with a lack of enzyme activity. A homozygous deletion in the GSTT1 has also been reported (null genotypes of GSTT1). The aim of the present study was to investigate the association between GSTM1 and GSTT1 polymorphisms and risk of dependency to opium sap. The present study was performed in Shiraz (southern Iran). In total, 71 males dependent to opium sap and 590 healthy males (as a control group) were included in this study. The genotypes of GSTM1 and GSTT1 polymorphisms were determined by PCR. Our data indicate that neither GSTM1 (OR=0.78, 95% CI: 0.47-1.27, P=0.325) nor GSTT1 (OR=1.25, 95% CI: 0.70-2.21, P=0.442) null genotypes significantly associated with the risk of opium sap dependence. There is no additive effect of the null genotypes of GSTT1 and GSTM1 in relation to the risk of dependency to opium sap. The present study indicated that the null genotypes of GSTT1 and GSTM1 are not risk factor for opium sap dependence.