Vitamin D receptor gene polymorphism TaqI (rs731236) and its association with the susceptibility to coronary artery disease among Pakistani population.

BACKGROUND Coronary artery disease (CAD) is a leading cause of mortality in Pakistan and also worldwide. Vitamin D receptor (VDR) regulates the transcription of many genes and has a significant impact on inflammation and the morphology of cardiac cells. Genetic variation in the VDR gene such as the TaqI polymorphism (rs731236) may have an impact that causes adverse effects. Accordingly, it is important to determine possible association of the TaqI polymorphism (rs731236) with CAD. METHODS The study included blood samples from 1016 subjects: 516 from CAD patients and 500 from age- and gender-matched controls. Genomic DNA was extracted by standard salting out method. Targeted variation was amplified by an allele-specific polymerase chain reaction (PCR). PCR products were examined and genotyped on agarose gel electrophoresis represented by an amplified product size of 148 bp followed by Sanger sequencing to validate variations. RESULTS Serum vitamin levels, as observed using enzyme-linked immunosorbent assay, were found to be insufficient in both CAD patients (20.52 ± 0.06 ng/ml) and controls (21.6981 ± 0.05 ng/ml). The TaqI polymorphism (rs731236) T>C was found to be significantly associated with CAD (p < 0.0001). The odds ratio showed that the risk increases by 1.8-fold with variant C allele. Dominant, co-dominant and over dominant genetic model analyses suggested that the TC genotype might be a risk factor involved in the possible association with susceptibility to CAD. CONCLUSIONS The TaqI polymorphism (rs731236) in the coding region may affect the function of the receptor by altering the binding site, which might participate in an inflammatory response and increase the risk for developing susceptibility to CAD.