Association between Bsm1 Polymorphism in Vitamin D Receptor Gene and Diabetic Retinopathy of Type 2 Diabetes in Korean Population

BACKGROUND Type 2 diabetes is one of the most common diseases with devastating complications. However, genetic susceptibility of diabetic complications has not been clarified. The vitamin D endocrine system is related with calcification and lipolysis, insulin secretion, and may be associated with many complicated disease including diabetes and cardiovascular disease. Recent studies reported that single nucleotide polymorphisms of vitamin D receptor (VDR) gene were associated with diabetic complications. METHODS In present study, we evaluated the association of BsmI polymorphism of VDR with diabetic complications in Korean diabetes patients. Total of 537 type 2 diabetic subjects from the Endocrinology Clinic of Chungbuk National University Hospital were investigated. Polymerase chain reaction-restriction fragment length polymorphism was used to test the genotype and allele frequency of BsmI (rs1544410; BB, Bb, bb) polymorphisms. RESULTS Mean age was 62.44±10.64 years and mean disease duration was 13.65±7.39 years. Patients with B allele (BB or Bb) was significantly associated with lower risk of diabetic retinopathy (severe non-proliferative diabetic retinopathy or proliferative retinopathy; 7.4%, 5/68) compared with patients without B allele (bb; 17.3%, 81/469; P=0.035). This association was also significant after adjusting for hemoglobin A1c level, body mass index, age, sex, and diabetes mellitus duration, concurrent dyslipidemia and hypertension (odds ratio, 2.99; 95% confidence interval, 1.08 to 8.29; P=0.035) in logistic regression analysis. CONCLUSION Our findings suggest that B allele of Bsm1 polymorphism in VDR gene is associated with lower risk of diabetic retinopathy in type 2 diabetic patients. Bsm1 genotype could be used as a susceptibility marker to predict the risk of diabetes complication.