Vitamin D receptor genotypes and bone mineral density.

The current study investigated the association between vitamin-D-receptor (VDR) genotypes with bone-mineral density (BMD) and its interaction with physical activity level (PAL). Individuals in a sample of 192 volunteers (67.84 +/- 5.23 years) underwent BMD evaluation and were genotyped for VDR ApaI, BsmI, FokI, and TaqI polymorphisms. Haplotypes were reconstructed through expectation-maximization algorithm, and regression-based haplotype-specific association tests were performed with studied phenotypes. None of the polymorphisms were associated with BMD at any site; however, haplotype was associated with femoral-neck and Ward's-triangle BMD. Interaction between PAL and VDR genotypes was significant for the FokI polymorphism at femoral-neck and Ward's-triangle BMD. The FokI T/T genotype was associated with higher BMD in active women. It was concluded that VDR haplotypes, but not genotypes, are associated with femoral-neck and Ward's-triangle BMD in postmenopausal women. Moreover, the results suggest that VDR FokI polymorphism might be a potential determinant of BMD response to physical activity.