VITAMIN-D-RECEPTOR GENE POLYMORPHISM IN MEN AND ITS EFFECT ON BONE-DENSITY AND CALCIUM-ABSORPTION

OBJECTIVE Previous studies have suggested that polymorphism of the all eles of the vitamin D receptor (VDR) gene may account for the major pa rt of the heritable component of bone density in women, possibly media ted in part by impaired calcium absorption from the bower, In view of the increasing importance of osteoporosis in men, we have now investig ated the association between common allelic variations in the vitamin D receptor gene, calcium absorption and bone density in men. SUBJECTS Forty-eight men (median age 64, range 27-77) with a wide range of bone density measurements, comprising 20 men with vertebral crush fracture s and 28 male control subjects, MEASUREMENTS Analysis of the VDR gene polymorphism and measurement of fractional radiocalcium absorption and bone mineral density was performed in all subjects, RESULTS The distr ibution of the three genotypes (TT, tt, Tt) was comparable to that rep orted previously. There was no significant difference in femoral neck bone density Z-scores between the three genotypes (mean +/- SD TT - 0. 31 +/- 1.19, tt - 0.08 +/- 1.28 and Tt - 0.37 +/- 1.17). There were al so no significant differences in mean femoral neck bone density T-scor es or lumbar spine bone density Z or T-scores between the three genoty pes, Fractional radiocalcium absorption was 0.59 +/- 0.27 for TT, 0.69 +/- 0.30 for tt and 0.60 +/- 0.30 for Tt, showing no significant diff erence between the genotypes. CONCLUSIONS This study shows no associat ion between vitamin D receptor gene polymorphism and bone density or f ractional calcium absorption in a group of men with a range of bone de nsity values. We conclude that the vitamin D receptor gene alleles pro bably account at most for only a small part of the genetic component o f bone density in men.