Molecular and Biochemical Study of Superoxide Dismutase Gene Polymorphisms in Egyptian Patients with Type 2 Diabetes Mellitus with and without Retinopathy

Abstract

Aims: This study aims to determine the antioxidant enzyme EC-SOD polymorphisms in Egyptian patients with type 2 diabetes mellitus with and without retinopathy, and its association with other biochemical changes to assess whether decreased SOD activity is associated with the development of diabetic complications. Study Design: Cross-sectional study. Place and Duration of Study: Department of Medicine Al-Hussein University Hospital, Cairo, Egypt, between May 2010 and April 2011. Methodology: The present study investigated the relationship among diabetes mellitus, lipid profiles, SOD activity, ESR, and CRP in the blood of 40 patients with type 2 diabetes with and without retinopathy and 20 healthy control subjects. The mean age of the diabetic patients was similar to that of control. The mean duration of the disease was 3.53 ± 1.17 years (1–5 years) in patients with type 2 diabetes without retinopathy and 18.7 ± 3.1 with retinopathy. Also we studied Arg213Gly dimorphism of the EC-SOD gene in type 2 diabetic patients with and without retinopathy and control persons using the PCR technique.  Results: Superoxide dismutase (SOD) level was significantly decreased in diabetics and more markedly decrease in those with retinopathy. Total cholesterol (CHOL), triglyceride (TG) and low-density lipoprotein-cholesterol (LDL-c) levels were significantly increased in diabetics and more markedly increased in those with retinopathy compared with the control level. Genotype distribution of the EC-SOD in diabetic patients with and without retinopathy differed from normal individuals, as the argentines-to-glycine amino acid substitution was higher in diabetic patients compared with the normal individuals. Conclusion: The present study revealed that hyperglycemia produced marked oxidation impact as evidenced by a significant increase in lipid profile, lipid per oxidation products, as well as a significant decrease in the total SOD activity. Moreover, it showed that the genotype distribution of the EC-SOD was differed as the arginine-to-glycine amino acid substitution was higher in diabetic patients with and without retinopathy compared with the control individuals. This report emphasizes the important role of superoxide dismutase and its genotype distribution in diabetic patients with and without retinopathy, and hence the need for antioxidant supplements to delay the severity of diabetic retinopathy.