GSTM1 and Hypertension: On the other hand Marinho and colleagues demonstrated that although GST activity and total plasma glutathione levels were markedly decreased in hypertension but there is no correlation with the GSTM1 and GSTT1 deletion polymorphisms [19].In our study it was seen that null GSTM1 and GSTT1 were not a significant risk factor for hypertension.