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 Parathormone hormone (iPTH) in hemodialysis patients (HD).
Methods: In this cross-sectional study, serums were obtained from 46 stable chronic HD patients. The serum levels of iPTH, Fetuin-A, vit D, calcium, phosphorus and VDR genotyping were determined by standard methods.
Results: The serum levels of Fetuin-A, calcium 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 pg/dl) vs. (414.7±111.8 pg/dl) p=0.04 and (24.5±7.6 ng/ml) vs.(19.9±4.8 ng/ml) p=0.02 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=0.02). There was a significant positive correlation between Vitamin D and iPTH levels in patients with aa genotype (p=0.02, 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.