Association Between Vitamin D Levels and Vitamin D Receptor (VDR) Gene Polymorphisms in Nepalese Population

Abstract

Background: Vitamin D deficiency is a global public health concern. Small variations in the proteins involved in vitamin D metabolism affect levels and physiological roles of vitamin D. However, there is a paucity of data regarding such factors in our population. This study was designed to assess the distribution of polymorphisms of vitamin D Receptor (VDR) gene (rs2238136 and rs731236) in vitamin-D deficient Nepalese population.
Methods: A total of 400 apparently healthy individuals visiting our center were enrolled. Five ml of blood was collected in gel vial and EDTA vial. The 25(OH)D levels were estimated in ABBOTT Architect autoanalyzer. After extracting genomic DNA, the VDR gene polymorphism (rs2238136 and rs731236) was analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The amplified products, 135 bp and 716 bp were digested using restriction enzymes Bpu10IA and TaqI for rs2238136 and rs731236, respectively, electrophoresed on 2% agarose gel and visualized under UV illuminator. Statistical analysis was done using SPSS version 21.0.
Results: The distribution of both rs2238136 and rs731236 followed Hardy-Weinberg equilibrium. There were 24 AA, 238 GG, and 138 AG genotypes found in rs2238136, whereas 226 TT, 34 CC, and 140 TC genotypes were found in rs731236. In contrast to rs731236, vitamin D levels varied among genotypes of rs2238136.
Conclusions: In our population, there was a higher prevalence of GG genotype (rs2238136) and TT genotype (rs731236). Increased prevalence of vitamin D deficiency in our region may be due to these genetic variations.
Keywords: Genetic polymorphism; restriction fragment length polymorphism; vitamin d; vitamin d receptor.