VITAMIN-D-RECEPTOR GENETIC-POLYMORPHISM A ND OSTEOPOROSIS

BACKGROUND: Genetic factors conditionate an important part of bone mas s, The role of vitamin D receptor polymorphism (VDR) as genetic marker of osteoporosis is a matter of discussion. We have studied the possib le influence of VDR on bone remodelling, calciotropic hormones, on the presence of osteoporosis and osteoporotic bone fractures. PATIENTS, C ONTROL POPULATION AND METHODS: A case-control study. We have studied a total of 127 postmenopausal canarian women from Canary Islands, Spain ; 66 healthy controls and 61 with the diagnosis of osteoporosis, which was made by clinical, radiological and densitometric criteria. 17 ost eoporotic women have had a fracture: Colles, hip or vertebral (spinal deformity index) fracture. VDR were determined by PCR directed to demo nstrate the presence (b) or ausence (B) of a restriction target for Bs ml in intron 7. We analized some biochemical markers of bone remodelli ng: serum levels of alkaline phosphatase, tartrate resistant acid phos phatase and urine ratios of calcium/creatinin and hydroxyproline/creat inin. We also determined calciotropic hormones: parathyroid hormone an d calcitonin. Bone mass was measured by DEXA and TC. RESULTS: There we re no significant differences in either biochemical bone remodelling m arkers or in bone mass between the three genotypes: bb, Bb and BE, eit her in controls or in osteoporotic women with the exception of alkalin e phosphatase which had a significative increase compared to control i n women with unfavorable alleles distribution (bB and BE). Distributio n of genotypes was similar between controls and osteoporotic women, wi th or without fractures. CONCLUSIONS: In canarian women, VDR genotype is not associated with changes in biochemical markers of bone remodell ing or in bone mass or with the presence of osteoporosis or osteoporot ic fractures.