Aim: Peak bone mass is a major determinant of osteoporosis risk in later life. It is under strong genetic control; In the present study, we investigated the relationship between polymorphisms in the gene encoding the vitamin D receptor (VDR) (FokI and Bsm 1) and bone mineral density (BMD), bone mineral content (BMC), and markers of bone turnover in 106 young Turkish women (1923 yrs) and 100 man (1923 yrs). Methods: BMD and BMC were measured by dual-energy X-ray absorptiometry (Lunar). Serum osteocalcin, C-teleopeptide (Ctx) and iPTH, calcium, phosphor and serum 25(OH)D levels were measured. Physical activity, dietary calcium and coffee consumption were assessed by questionnaire. Muscle strength was measured with hand dynamometer. PCR-RFLP methods were used for genotyping.
Results: Calcium, phosphor, PTH and 25(OH)D levels (43±20 ng/ml) were in normal range not different between man and women. BMD (lomber and femur area), muscle strength, calcium intake (680 mg/d vs 571 mg/d in women P=0.001), serum osteocalcin and CTx levels were significantly higher in man compared to women.
Frequencies of FF, Ff and ff genotypes were 44.3%, 47.1% and 8.4% in women, and 41.8%, 52.3% and 4.6% in man. Frequencies for BB, Bb were 15%, 52% and 33% in women, and 9.3%, 60.4% and 30.2% in man. Frequency distribution for Bsm and Fok polimorfisms were not different between man and women. Femur BMC was significantly low in bb genotype in women (P=0.01). Femur and lomber (L1-4) BMC were low in ff genotype in women. Serum calcium levels were found to be lower in ff genotype in women. Bone turnover markers were similar among genotypes both man and women.
Conclusion: VDR gene may influence on attainment and maintenance of peak bone mass. bb and ff genotypes may have a effect on bone metabolism during accumulation of peak bone mass in women.