Endocrine Abstracts

Objective: The aim of the present study was to assess the association between vitamin D receptor (VDR) gene polymorphism and bone mass indices in Indian adolescent girls.

Methods: The current study was a cross sectional one including 100 post menarcheal girls aged 15–18 years. Serum levels of ionized calcium, inorganic phosphorus, alkaline phosphatase, parathyroid hormone and 25 hydroxy vitamin D were measured. Bone mineral content (BMC), Bone area (BA) and bone mineral density (BMD) were measured at total body (TB), lumbar spine (LS) and left femoral neck (FN) using dual energy X-ray absorptiometry (Lunar DRX DPO). Polymorphisms of VDR gene at the Fok1 and Bsm 1 loci were detected using SYBR Green quantitative PCR.

Results: Vitamin D deficiency (serum 25-OH D3<30 ng/ml) was observed in 43% patients. The overall prevalence of genotype for Bsm1 in this study was 33.3% Bb, 29.2% bb and 37.5% BB. For Fok1 genotype, the prevalence was 44.2% Ff, 7.5% ff and 48.3% FF. There were no significant differences in the blood parameters when classified according to Bsm1 and Fok1 genotypes. Subjects with BB genotype have significantly higher mean TBBMC (1012±178 g), TBBA (1264±186 cm²), TBBMD (0.89±0.06 g/cm²) and LSBMD (0.81±0.04 g/cm²) than Bb and bb (P<0.05). They showed tendency for association with LSBMC and LSBA (P<0.1). Bsm 1 genotype did not show an association with FN bone indices whereas Fok1 genotype did not show an association with TB, LS or FN bone indices.

Discussion: Vitamin D is important for bone health. Vitamin D deficiency is common among children and adolescents in India, in spite of abundant sunshine. With respect to the Bsm1 genotype, the Bb and bb subgroups were more prevalent (62.5%) than BB (37.5%) and were associated with worse bone health parameters. Whereas with respect to the Fok1 polymorphism, FF genotype was most common (48.3%). But there was no difference in the bone health parameters among different subgroups.

Conclusion: The present study demonstrates VDR gene polymorphism; defined by Bsm 1 genotype has an influence on total body and lumbar spine bone mass indices in post menarcheal Indian girls.