Vitamin D receptor polymorphisms in overweight/obese chronic kidney disease patients undergoing hemodialysis

Background: Many studies were carried out to investigate the relationship between single nucleotide polymorphisms (SNPs) in vitamin D receptor (VDR) gene with obesity. However, little is known about the role of VDR gene polymorphism with obesity in hemodialysis (HD) patients. Therefore, we aimed to investigate VDR gene TaqI, ApaI and FokI SNPs in overweight/obese HD patients. Methods: Seventy one normal weight and 68 overweight/obese HD patients were included in study. PCR-RFLP method was used for genotyping. Demographic and laboratory data obtained from medical records of patients. Results: For all three SNPs, no significant association was found between normal and overweight/obese patients (P>0.05). Lower HDL concentrations and higher levels of triglyceride (TG) and glucose were detected in the obese/overweight patients compared to normal weight (p<0.001 for HDL, and TG and p=0.023 for glucose). In obese/overweight patients, subjects with CC genotype of TaqI showed higher PTH level (717.1{+/-}616.4 pg/ml) than those TC genotype (342.7{+/-}360.8 pg/ml) and TT genotype (310.2{+/-}323.4 pg/ml) (p=0.028); higher TG level was found in patients with CC genotype of ApaI (627.3{+/-}653.0 mg/dl) compared to AA (223.3{+/-}156.6) and AC genotypes (193.1{+/-}85.4) (p<0.001). Obese/overweight patients carrying FokI TT genotype had higher glucose concentration compared to those carrying CC and CT genotypes (CC=183.4{+/-}128.4 mg/dl; TT=151.9{+/-}66.1 mg/dl; CT=107.6{+/-}41.9 mg/dl, p=0.008). Conclusions: Our study suggest that VDR TaqI, ApaI and FokI polymorphisms are not associated with obesity in HD patients. However, they might be increase the risk of secondary hyperparathyroidism, dyslipidemia, and hyperglycemia, which are among the most common obesity related comorbidities of chronic kidney disease.