Association of XbaI GLUT1 Polymorphism with Susceptibility to Type 2 Diabetes Mellitus and Diabetic Nephropathy

Objectives: Diabetic nephropathy (DN) is one of the chronic microangiopathic complications of type 2 diabetes (T2DM) and has become the most frequent cause of end-stage renal disease. The XbaI polymorphism in the glucose transporter (GLUT1) has been suggested in the development of DN. We examined the association between XbaI polymorphism of GLUT1 and susceptibility to T2DM and development of DN. Methods: The study included 227 T2DM patients divided into 107 without DN (DM ? DN) and 120 with DN (DM + DN), in addition to 100 apparently healthy controls. Genotyping was done by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Results: The GLUT1 XbaI T allele was associated with increased susceptibility to T2DM, when comparing the healthy controls to the whole diabetic group, odds ratio (OR) = 1.899, 95% confidence interval (CI) (1.149 - 3.136), p = 0.011. This association was also significant between healthy controls and DM ? DN OR = 1.997 (1.079 - 3.699), p = 0.026 as well as between healthy controls and DM + DN OR = 1.818 (1.016 - 3.253), p = 0.042. However there was no significant association of XbaI polymorphism with DN when comparing DM ? DN to DM + DN OR = 0.910 (0.474 - 1.747), p = 0.777. Conclusion: XbaI T allele is associated with increased susceptibility to T2DM, but not to development of DN. Further studies are needed to replicate such findings.

The C161T Polymorphism in Peroxisome Proliferator-Activated Receptor ɣ2, but Not Pro12Ala, Is Associated with Diabetic Retinopathy in Type 2 Diabetes Mellitus in an Egyptian Population

Objectives: Diabetic retinopathy (DR) is one of the most common microvascular complications of type 2 diabetes mellitus (T2DM). It is multifactorial with the contribution of multiple genetic factors. We questioned the association of polymorphisms in the peroxisome proliferator-activated receptor ?2 (PPAR?2) gene (Pro12Ala and C161T) with DR in an Egyptian population. Methods: This case control study included one hundred healthy individuals and 252 T2DM among them 122 with DR and 130 without DR. Genotyping was done by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Results: The Pro12Ala Ala allele was associated with decreased risk of DR with an odds ratio (OR) of 0.484, 95% confidence interval (CI) (0.254 - 0.920), and a p value = 0.024. The C161T T allele was associated with increased risk of DR with OR = 2.593, 95% CI (1.672 - 4.020), p < 0.001. However, when considering other covariates such as glycosylated hemoglobin (HbA1c) in multivariate regression analysis only C161T was associated with increased risk of DR with OR = 3.479, 95% CI (1.907 - 6.346), p < 0.001, while the significant association with Pro12Ala was lost. HbA1c was higher in Pro/Pro genotype when compared to those with Ala/Ala and Pro/Ala genotypes. Conclusion: We report that T allele of C161T increased risk of DR in the studied population. Further studies are warranted to investigate functional implications of polymorphisms of the PPAR-? gene in DR development.