IS THE BONE MASS OF HEMODIALYSIS-PATIENTS GENETICALLY-DETERMINED

Polymorphism of the vitamin D receptor gene (VDR) has been linked to b one mineral density in twins, postmenopausal osteoporosis, and premeno pausal woman. We examined the possibility that the bone mass in hemodi alysis (HD) patients might be determined by VDR. The study consisted o f 229 HD patients with a mean age of 53.3 years (range 21 to 83), who were dialyzed three times a week fur an average of 8.65 (range 0.2 to 24) years. We determined their VDR using DNA of peripheral white blood cells by restriction enzyme BsmI and the polymerase chain reaction-re striction fragment length polymorphism method. Bone mineral content (B MC) was estimated at 1/3 of the radius using dual energy X-ray bone ab sorptiometry, and expressed in z-scores standardized by gender and age . Distributions of VDR in this hemodialysis population were BE (9.9%), Bb (13.1%), and bb (77.0%), showing no significant different from tho se in 105 healthy volunteers (BE, 7.6%; Bb, 13.3%; and bb, 79.0%). Mul tiple regression analysis revealed that gender, age, duration on HD, a nd serum osteocalcin are major determinants of BMC (r = 0.762, P < 0.0 01), while VDR and serum parathyroid hormone are not. In a subgroup wi th younger (< 65 years) patients dialyzed for less than 8.65 years, th e z-score of BMC of patients with BE allele was less than those with B b and bb allele (N = 77, P = 0.020). We conclude that vitamin D recept or polymorphism is not one of the main determinants of BMC of HD patie nts, though it might partially effect bone mass in a subgroup of young er HD patients with shorter HD histories. Further studies with longitu dinal observation will be needed to confirm these possibilities.