Fetuin-A and vitamin D receptor gene polymorphisms in hemodialysis patients

Introduction: Vascular calcification is a common complication in the chronic kidney disease (CKD) patients and the leading cause of morbidity and mortality in this patient. The aim of the present study was to evaluate a possible correlation between vitamin D receptor (VDR) gene FokI and ApaI polymorphisms with the expression of calcification biomarkers such as Fetuin-A and intact parathyroid hormone (iPTH) in hemodialysis (HD) patients. Methods: In this cross-sectional study, serums were obtained from 46 stable chronic HD patients. The serum levels of iPTH, Fetuin-A, vitamin D, calcium, phosphorus, and VDR genotyping were determined by standard methods. Results: Serum levels of Fetuin-A, calcium, and phosphorus did not differ between males and females, but significant differences in iPTH and vitamin D levels was found in the study patients [(336.8 ± 139.0 pg/dl) vs. (414.7 ± 111.8 pg/dl), P = 0.040 and (24.5 ± 7.6 ng/ml) vs. (19.9 ± 4.8 ng/ml), P = 0.020 respectively]. A significant correlations were found between serum phosphorus and levels of serum calcium (r = –0.4; P = 0.002), vitamin D (r = –0.5; P = 0.001) and iPTH (r = 0.4; P = 0.001). iPTH level in FokI polymorphism, were different between genotype groups in study patient (P = 0.020). There was a significant positive correlation between vitamin D and iPTH levels in patients with aa genotype (P = 0.020, r = 0.4). Conclusion: These findings suggest that FokI (rs2228570) polymorphism in exon-2 of the VDR gene may play a role in iPTH levels. Fetuin-A deficiency or high level of iPTH and its association with VDR gene polymorphisms may be useful to identify the high-risk group susceptible to renal failure and atherosclerosis. Although VDR gene FokI and ApaI polymorphisms could affect the levels of Fetuin-A and vitamin D, their direct role on atherosclerosis needs further studies in the future.