We investigated the effect of vitamin D receptor gene (VDRG) polymorphism on the responsiveness to 1,25(OH)₂D₃ in human osteoblast-like cells. The cells were obtained from the femoral heads of 18 women with osteoarthritis of the hip. Three different restriction enzymes, BsmI, ApaI, and TaqI, were used to analyse the polymorphism. The genotypes of the 18 patients were bbAaTT (8), bbaaTT (6), BbAaTt (3), and BbAATt (1).

Our findings showed that there were no differences according to the VDR genotype, but there was a statistically significant difference in the production of osteocalcin between BbAaTt and bbAaTT, and between BbAaTt and bbaaTT. Northern blot analysis of osteocalcin and VDR mRNA showed no significant differences among the three VDR genotypes. These findings suggest that VDR gene polymorphism affects the individual responsiveness of 1,25(OH)₂D₃.