Effect of GSTM1 and GSTT1 double deletions in the development of oxidative stress in diabetic nephropathy patients.

Association of diabetic nephropathy (DN) with the deletion of GSTT1 and GSTM1 genes is well reported. Oxidative stress (OS) has also been associated with the development of DN. The present study was conducted to find out, whether these deletions had any contributory role in the development of OS in patients with DN. Pre-dialysis venous blood samples were obtained from 60 patients with diabetic end-stage renal disease (stages 4 and 5). Reduced-glutathione (GSH), glutathione S-transferase (GST) activity and malondialdehyde (MDA) levels were measured for the assessment of OS. Genetic polymorphism analysis of DN patients revealed the following distribution pattern: GSTM1 null 46.7%; GSTT1 null 55%; both null 30% and both positive 28.3%. Patients with both null genotypes were found to have significantly increased levels of MDA and low GST activity as compared to other genotypic groups. Lower GSH levels were observed in all the genotypic groups as compared to both positives. Double deletions involving GSTT1 and GSTM1 may result in decreased GST levels, leading to increased OS as reflected by increased MDA levels. As GST is a multi-functional enzyme involved in xenobiotic metabolism, this double null genotype population has a greater risk of development of DN. Further studies using increased sample size to find out the allelic distribution and their role in the development of DN are in progress.