Lack of Correlation Between Start Codon Polymorphism of the Vitamin D Receptor Gene and Bone Mineral Density in Premenopausal French Women: The OFELY Study



Previous studies have demonstrated an association between bone mineral density (BMD) and a start codon polymorphism (SCP) of the vitamin D receptor (VDR) gene in pre- and postmenopausal Caucasian and Japanese women. The SCP can be determined by a restriction fragment length polymorphism defined by the FokI restriction endonuclease. VDR alleles containing the FokI site are denoted by f and alleles lacking the site by F. In this study, the association between BMD and the SCP was examined in a group of 174 premenopausal French women who previously had been studied for a relationship between BMD and the VDR BsmI polymorphism. The SCP genotypes of the French women were FF 40%, Ff 44%, and ff 16% and they were independent of the BsmI genotype. BMD was measured by dual-energy X-ray absorptiometry at the lumbar spine, proximal femur, forearm, and total body. In contrast to previous reports, there was no association of BMD with SCP genotype in this group of Caucasian women at any site. We also measured several biochemical indices of calcium homeostasis and bone turnover. We found no statistically significant associations between SCP genotype and calcium, parathyroid hormone, or vitamin D levels. There was a 33.5% higher level of the skeletal resorption marker N-telopeptides of type I collagen in the women with the ff genotype when compared with women with the FF genotype (p = 0.004). Other bone turnover markers failed to show an association with SCP genotype. In summary, the SCP genotype may not be associated with reduced BMD in all geographical or ethnic populations.