The relationship between aldose reductase gene C106T polymorphism and the severity of retinopathy in Type 2 diabetic patients: A case-control study

Background: Hyperglycemia over-activates glucose reduction to sorbitol by aldose reductase (ALR) leading to osmoregulation disruption and cellular damage that cause diabetic complications. We investigated the association of C106T polymorphism of ALR2 gene with the severity of diabetic retinopathy (DR) in Jordanian Type 2 diabetic patients in this case-control study at the Ophthalmology clinic of the National Centre of Diabetes, Endocrinology, and Genetics. Materials and Methods: A total of 277 subjects participated in the study (100 diabetics without retinopathy, 82 diabetics with retinopathy, and 95 controls). Blood samples were withdrawn followed by DNA extraction. C106T polymorphism was examined by polymerase chain reaction followed by restriction fragment length polymorphism and gel electrophoresis. Statistical analysis was performed by SPSS software using analysis of variance, multiple logistic regression or Chi-square test. Results: The CT and TT genotypes were significantly more prevalent in DR patients than those without DR (CT 50% vs. 38%, TT 16.7% vs. 8%, P = 0.02 and 0.01, respectively). DR patients had T allele more frequently than those without it (41.7% vs. 27%, P = 0.007). Diabetics without retinopathy showed similar genotype and allele frequency to those of nondiabetic controls. No correlation between CT/TT genotypes and the severity of DR in affected subjects was found (chi 2: 3.049, P = 0.550). Conclusion: C106T polymorphism increased the risk to develop retinopathy in Jordanian Type 2 diabetic patients. T allele of ALR2 was associated with DR. The severity of DR did not show an association with this polymorphism.