Clinical aspects of vitamin D-binding protein gene polymorphisms in hemodialysis patients

INTRODUCTION There are scarce data on the associations between vitamin D-binding protein gene (GC) polymorphisms and manifestations of chronic kidney disease.

OBJECTIVES We evaluated the frequency distribution of GC polymorphic variants in hemodialysis (HD) patients and healthy subjects as well as the differences in the prevalence of coronary artery disease (CAD) and myocardial infarction (MI) and selected clinical and laboratory indices of secondary hyperparathyroidism in HD patients (women and men) with different GC polymorphic variants.

PATIENTS AND METHODS HD patients (n = 1056; 625 men) and healthy controls (n = 313; 150 men) were enrolled into the study. The tested GC polymorphisms included rs2298849, rs7041, and rs1155563. We analyzed clinical data (prevalence of CAD and MI; treatment with parathyroidectomy or cinacalcet) and laboratory results (serum calcium, phosphorus, alkaline phosphatase, parathyroid hormone, and 25-hydroxy vitamin D [25(OH)D] in relation to the gene polymorphisms.

RESULTS There were no differences between the study groups themselves and between the study groups and controls in terms of the frequency distribution of GC polymorphisms (Ptrend <0.05). Lower plasma 25(OH)D levels were shown in subjects with the rs7041 TT genotype compared with those with the GG genotype (12.7, 5.7–20.9 ng/ml vs. 15.9, 8.0–50.0 ng/ml, P = 0.02). Women with the rs7041 TT genotype compared with those with the GG genotype showed higher serum phosphorus levels (5.58, 3.40–8.97 mg/dl vs. 5.03, 1.75–9.33 mg/dl, P = 0.007). 

CONCLUSIONS HD patients do not differ in the distribution of GC polymorphisms rs2298849, rs7041, and rs1155563 from healthy subjects. In HD patients, the GC polymorphism is associated with plasma 25(OH)D levels. Sex-related factors may be important in the expression of associations between GC polymorphic variants and mineral disorders.