Association of +35A/C (intron3/exon3) polymorphism in SOD1-gene with diabetic nephropathy in type 1 diabetes

Diabetic nephropathy is a major complication of type 1 diabetes whose pathogenesis is insufficiently known, but oxidative stress and genetic susceptibility seem to be involved. The purpose of this study is to assess the possible association of +35A/C (rs2234694) polymorphism in SOD1-gene with advanced stages of diabetic nephropathy in patients with type 1 diabetes in Romania. There have been enrolled 238 unrelated patients, having type 1 diabetes, divided into group A (106 patients) with diabetic nephropathy - macroalbuminuria or ESRD (End Stage Renal Disease) and group B (132 patients) without diabetic nephropathy. The genomic DNA was extracted from the peripheral venous blood and the genotyping of +35A/C (rs2234694) polymorphism has been made using the PCR-RFLP technique. The statistical analysis has been made using De Finetti's program. There has not been a significant deviation from the Hardy-Weinberg equilibrium for any group (p=0.229 and p=0.894, respectively). The data analysis revealed that the presence of a C-allele confers a significant risk (p=0.008) for the advanced diabetes nephropathy (OR=4.940, 95% C.I.=1.341-18.198), and the CA-genotype (p=0.015) confers a little lower risk (OR=4.491, 95% C.I.=1.203-16.766). This study shows the association of a mutant C-allele of rs2234694 polymorphism in SOD1-gene with the advanced stages of diabetic nephropathy in patients with type 1 diabetes in Romania, suggesting the involvement of the defense against oxidative stress, as an important link in the pathogeny of diabetic nephropathy.