Parathyroid hormone gene polymorphism and secondary hyperparathyroidism in hemodialysis patients

It is well known that genetic factors are involved in the progression of secondary hyperparathyroidism (HPT) in hemodialysis (HD) patients. The purpose of the present study is to determine the relationship between restriction fragment length polymorphisms (RFLPs) of the parathyroid hormone (PTH) gene and serum intact PTH levels in HD patients. Eighty-six HD patients not treated with vitamin D and 80 healthy controls were analyzed. PTH genotypes were determined by polymerase chain reaction and RFLPs of BstBI and DraII. The presence or absence of BstBI and DraII restriction sites of the PTH gene were indicated by B or b and D or d, respectively. There were no significant differences in frequencies of each genotype between HD patients and healthy controls. In HD patients, serum intact PTH levels in the Dd/dd genotype were significantly greater than those in the DD genotype (P < 0.02). However, there was no significant difference in serum intact PTH levels between Bb/bb and BB genotypes. Serum intact PTH levels in the non-BBDD haplotype were significantly greater than those in the BBDD haplotype (P < 0.01). Serum intact PTH levels correlated negatively with serum calcium (Ca) and magnesium (Mg) levels and positively with alkaline phosphatase levels in simple regression analysis. However, in forward stepwise multiple regression analysis, only serum Ca and Mg levels predicted serum intact PTH levels. We conclude that PTH genotypes may influence secondary HPT in HD patients.