Allelic variations of the vitamin D receptor (VDR) gene are associated with increased risk of coronary artery disease in type 2 diabetics: The DIABHYCAR prospective study

Abstract Aim Vitamin D deficiency is associated with coronary artery disease (CAD), and the actions of vitamin D are mediated by binding to a specific nuclear vitamin D receptor (VDR). This study investigated the associations of VDR gene variants with CAD in two cohorts of type 2 diabetes patients. Methods A cohort of 3137 subjects from the prospective DIABHYCAR study (CAD incidence: 14.8%; follow-up: 4.4±1.3 years) and an independent, hospital-based population of 713 subjects, 32.3% of whom had CAD, were assessed. Three SNPs in the VDR gene were genotyped: rs1544410 ( Bsm I); rs7975232 ( Apa I); and rs731236 ( Taq I). Results In the DIABHYCAR cohort, an association was observed between the A allele of Bsm I and incident cases of CAD (HR: 1.16, 95% CI: 1.05–1.29; P =0.002). Associations were also observed between Bsm I ( P =0.01) and Taq I ( P =0.04) alleles and baseline cases of CAD. The AAC haplotype ( Bsm I/ Apa I/ Taq I) was significantly associated with an increased CAD prevalence at the end of the study compared with the GCT haplotype (OR: 1.12, 95% CI: 1.02–1.28; P =0.04). In a cross-sectional study of the independent hospital-based cohort, associations of Apa I ( P =0.009) and Taq I ( P =0.03) alleles with CAD were observed, with similar haplotype results (OR: 1.33, 95% CI: 1.03–1.73; P =0.03). Conclusion The haplotype comprising the minor allele of Bsm I, major allele of Apa I and minor allele of Taq I of VDR (AAC) was associated with an increased risk of CAD in type 2 diabetes patients. This effect was independent of the effects of other known cardiovascular risk factors.