Osteocalcin gene polymorphism is related to bone density in healthy adolescent females

Recently a polymorphism was found in the human osteocalcin gene, and its as sociation with bone mass was investigated in healthy postmenopausal Japanes e women. The osteocalcin gene allelic variant HH was found to be overrepres ented in women with osteopenia. The purpose of this study was to investigat e whether the previously demonstrated polymorphism of the osteocalcin gene was related to bone mineral density (BMD; g/cm(2)) or osteopenia in a group of 97 healthy Caucasian adolescent females (aged 16.9 +/- 1.2 years, mean +/- SD). BMD of the left humerus, right femoral neck, lumbar spine and tota l body was measured using dual-energy X-ray absorptiometry. The relation be tween the allelic variants and bone density was analyzed as presence or abs ence of the H allele. Presence of the H allele was found to be related to a lower BMD of the humerus (0.97 vs 1.02, p = 0.03). There was also a strong tendency towards significance at the femoral neck (p=0.06) and total body (p=0.11). Using a multiple linear regression and including physical activit y, weight, height and years since menarche, presence of the H allele was fo und to be an independent predictor of humerus BMD (beta = - 0.21, p<0.05) a nd femoral neck BMD (<beta> = -0.23, p<0.01). Using logistic regression, pr esence of the H allele was also independently associated with a 4.5 times i ncreased risk of osteopenia (p = 0.03) in the whole group. Osteopenia was d efined as at least 1 SD lower bone density than the mean for the whole grou p of at least one of the BMD sites measured. We have demonstrated that the osteocalcin HindIII genotype is independently related to bone density in he althy adolescent females. The present study also suggests that presence of the H allele is predictive of osteopenia at an early age.