Vitamin D receptor gene polymorphisms and bone mass indices in post-menarchal Indian adolescent girls

To study the association between vitamin D receptor (VDR) gene polymorphisms and bone mass indices in adolescent girls, a cross-sectional study was conducted in 120 post-menarchal girls aged 15-18 years in Pune city, India. Serum levels of ionised calcium, inorganic phosphorous, 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. Polymorphisms of the VDR gene at the Fok1 and Bsm1 loci were detected using SYBR Green quantitative polymerase chain reaction. The overall distribution of genotypes at the Bsm1 locus in this study was 33.3 % Bb, 29.2 % bb and 37.5 % BB while that for the Fok1 locus 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 or Fok1 genotypes. Subjects with BB genotype have significantly higher mean TBBMC, TBBA, TBBMD and LSBMD than Bb and bb (p < 0.05) and showed a tendency for association with LSBMC and LSBA (p < 0.1). Subjects with Ff genotype showed a tendency for association with left FNBMC and FNBA (p < 0.1). Bsm1 genotype did not show an association with FN bone indices whereas Fok1 genotype did not show association with TB or LS bone indices. In conclusion, the present study demonstrates VDR gene polymorphism, defined by Bsm1 genotype, has an influence on total body and lumbar spine bone mass indices in post-menarchal Indian girls.