The association of manganese superoxide dismutase gene polymorphism (Rs4880) with diabetic macular edema in a cohort of type 2 diabetic Egyptian patients

Abstract

Abstract Background Diabetic retinopathy (DR) and diabetic macular edema (DME) are the leading causes of blindness in patients with diabetes. Increasing numbers of people with diabetes worldwide suggest that DR and DME will continue to be major contributors to vision loss and associated functional impairment for years to come. Oxidative stress is a key participant in the development and progression of diabetes mellitus (DM) and its complications. Antioxidant status can affect vulnerability to oxidative damage, onset and progression of diabetes, and complications of diabetes. Manganese superoxide dismutase (Mn-SOD) is a key mitochondrial enzyme in cell defense against reactive oxygen species (ROS). DR and progression to DME have been associated with polymorphism in the second exon of the Mn-SOD gene at the 16th amino acid (Ala16Val) in the mitochondrial targeting sequence (MTS) of the protein. The study aimed to investigate the association between Ala16Val Mn-SOD gene polymorphism and the susceptibility to DR and DME in type 2 DM (T2DM). Results In this study, 150 patients with type 2 DM were enrolled: 100 patients with DR with and without diabetic macular edema (DME) and 50 patients with type 2 diabetes with a duration of 10 years without DR. Ala16Val SNP of the Mn-SOD gene (rs4880) was detected by TaqMan real-time PCR. The results showed that the homozygous polymorphic variant VV between the DME group is significantly higher than the non-DME group (P 0.018) among the DR group. Conclusion Mn SOD A16V polymorphism itself may not be associated with DR; meanwhile, it may be implicated in the pathogenesis of DME.

Keywords

• Diabetic retinopathy
• Mitochondrial targeting sequence
• Diabetic macular edema
• Mn-SOD gene
• Ala16Val (rs 4880)