Genetic variations of vitamin D receptor gene in metabolic syndrome and related diseases in the Thai population

Background and Objectives: The genetic variations of vitamin D receptor (VDR) have revealed its association with the risk of metabolic syndrome (MetS). In Thailand, evidence of this association has not been obtained. Thus, this study aimed to investigate the association of VDR gene polymorphism with MetS and related diseases as well as the possible linkage disequilibrium (LD) and haplotypes of VDR in Thai adults. Methods and Study Design: Four single nucleotide polymorphisms (SNPs) of VDR gene, rs2228570, rs1544410, rs7975232 and rs731236, were genotyped using PCR-RFLP method in 259 MetS and 261 control groups. Results: Genotypes AA of rs1544410, TG of rs7975232 and TG+TT of rs7975232 were significantly associated with an increased risk of MetS [OR 10.8 (2.07-56.1), p=0.005], [OR 1.83 (1.16-2.87), p=0.009] and [OR 1.78 (1.17-2.72), p=0.007], respectively, using GG as a reference. Moreover, genotype AA of rs1544410 showed a strong association compared with GG+AG [OR 11.4 (2.20-59.2), p=0.004]. Diseases related to MetS also had significant associations with two SNPs of the VDR gene (rs1544410 and rs7975232). In addition, LD among rs1544410, rs7975232 and rs731236 was detected. Haplotype CATT significantly increased the risk of MetS [OR 4.32 (1.32- 14.1), p=0.016], although haplotype TGGT reduced the risk [OR 0.68 (0.48-0.98), p=0.042]. Conclusions: The SNPs rs1544410 and rs7975232 were mainly implicated in the increased risk of MetS in the Thai population. LD and haplotypes of VDR gene related to MetS were also discovered. These SNPs of VDR gene are remarkable genetic factors involved in the development of MetS.