GST Polymorphisms and GST Enzyme Activity in Type 1 Myotonic Dystrophy

Glutathione S-transferases (GSTs) play an important role in protecting cells from damage caused by endogenous and exogenous compounds. In present study, we investigated the association of GST gene polymorphisms (GSTT1, GSTM1, GSTP1 and GSTM3) and its enzyme activity in DM1 affected Indian population. Serum GST level was assessed by using GST-kit. GSTM1 (null or present) & GSTT1 (null or present) GSTM3 (AA, AB and BB) & GSTP1 (Ile/Ile, Ile/Val and Val/Val -105) polymorphism were analyzed. The serum GST significantly reduced in the patient group compared to the control group and significantly correlated with diabetes. Patients had significantly higher (except GSTM3A/B) GSTM1*0 (GSTM1 null genotype), GSTT1*0 and GSTP1 (ile/val) frequency than controls. The deletion frequencies (GSTM1 and GSTT1) and GSTP1 (ile/val) were not associated with higher risk while heterozygous frequency of GSTM3 (A/B) increased risk ratio up to three fold. The GSTM1, GSTT1, GSTM3 genotypes correlated with dyspepsia, age at presentation and duration of disease respectively. The allelic frequencies were 0.46, 0.54 and 0.48, 0.52 for GSTM3*A and GSTM3*B and were 0.61, 0.39 and 0.55, 0.45 for ile (A) and val (G) of GSTP1 for DM1 patients and control group respectively. The group of combination genotype frequency had no impact on higher risk of disease. GSTT1 and GSTM1 seem to be a candidate gene for susceptibility to DM1 in Indian population. Further studies using genetic polymorphisms of glutathione or other antioxidant enzymes are required to clarify the relationship between increased oxidative stress and DM1.