VKORC1 gene (vitamin K epoxide reductase) polymorphisms are associated with cardiovascular disease in chronic kidney disease patients on hemodialysis

Abstract

Vitamin K is necessary for the carboxylation of clotting factors and matrix Gla protein (MGP). Vitamin K epoxide reductase (VKOR) is the enzyme responsible for recirculation of Vitamin K increasing its tissue availability. Polymorphisms of VKOR may alter the function of MGP, thereby influencing vascular calcification. We conducted this study to investigate the relationship of VKORC1 gene single nucleotide polymorphisms (SNP's) to vascular calcification and clinically overt cardiovascular disease in chronic kidney disease (CKD) patients on hemodialysis (HD). The study included 54 CKD patients on HD. We excluded those with diabetes or on anticoagulant therapy. Vascular calcifications were measured using computerized tomography scans and roentgenograms. Prevalent clinically overt cardiovascular disease was reported based on the evidence of documented preexisting major cardiovascular events. Genotype detection for the gene VKORC1 C1173T and G-1639A polymorphisms was carried out by polymerase chain reaction. We found a significant association between C1173T polymorphisms and vascular calcification (odds ratio [OR] = 43, P = 0.001). The mutant T allele was also linked with higher odds of vascular calcification (OR = 8.880, 95% confidence interval [CI] = 3.1-25.4, P = 0.001) and clinically overt cardiovascular disease (OR = 4.7, 95% CI = 1.5-14.7, P = 0.005). VKORC1 G-1639A polymorphisms were not associated with vascular calcification and had lower prevalence of clinically overt cardiovascular disease (OR = 0.07, 95% CI = 0.01-0.4, P = 0.001). In patients with CKD on HD, we found that VKORC1 gene polymorphisms did have an association with prevalent cardiovascular calcification and clinically overt cardiovascular disease, C1173T polymorphisms with higher risk for disease, and G-1639A with lower risk.