Abstract
Polymorphisms of vitamin D receptor (VDR) and parathyroid hormone (PTH) genes have been demonstrated in several studies to be linked with bone mineral density and parathyroid function. In patients with end-stage renal disease (ESRD), vitamin D and / or PTH play important roles in the progression of secondary hyperparathyroidism. In this study, the influence of VDR gene and PTH gene polymorphisms on parathyroid function was evaluated in 189 patients with ESRD, of whom 150 received hemodialysis and 39 continuous ambulatory peritoneal dialysis (CAPD). VDR gene polymorphisms were defined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) using Bsm-I and Fok-I and PTH gene polymorphisms were similarly defined by PCR-RFLP using Bst-BI and Dra-II. VDR genotypes were BB = 7%, BB = 16%, bb = 77%, and FF = 47%, Ff = 42%, ff = 11%. PTH genotypes were BtBt = 3%, Btbt = 21%, btbt = 76% and DD = 1%, Dd = 17%, dd = 82%. Patients without the VDR f allele of showed significantly lower serum intact PTH (91 ± 11: 128±14 pg / ml, p < 0.05) and higher serum phosphate (5.7 ± 0.2: 5.1 ± 0.1 mg / dl, p < 0.01) than those with the f allele. In the non-diabetic nephropathy group, serum intact PTH of patients without the f allele was clearly lower than in those with the fallele (84 ± 14: 136 ± 16 pg / ml, p < 0.01), but no differences were seen in other clinical parameters. The fallele frequency was significantly higher in the high PTH group --(over 300 pg / ml and parathyroidectomy)-- than in the low PTH group --(under 65 pg / ml)(0.75 : 0.46, p < 0.05). In VDR gene polymorphism by Bsm - I and in PTH gene polymorphisms by Bst - BI or Dra - II, no relationship was seen between gene polymorphisms and clinical parameters. Our results indicate that parathyroid function may be influenced by the Fok-I polymorphism of the VDR gene in patients with ESRD.
