Heritability of bone mineral density

Objective. To evaluate the influence of genetic background as a determinant of peak bone mass. Patients and methods. We compared lumbar spine bone min eral density in 175 girls with a bone age of 16 years or older and in their premenopausal mothers. We also investigated the influence of a family hist ory of osteoporosis on lumbar spine bone mineral density in 275 women and t heir 559 daughters. Results. In the 178 mother-daughter pairs, heritability (h(2)) was significantly different from 0 (P<0.0001) for lumbar spine bone mineral density (h(2)=53%; 95% confidence Interval [95% CI]=28.5-77.6%), b one mineral content (h(2)=62.3%; 95% CI=37.7-88.8%), bone mineral density a djusted for body mass index (h(2)=56%; CI=31.5-80.5%), and bone mineral con tent adjusted for body mass index (h(2)=68.2%; CI=43.8-92.7%), However, the heritability estimations lacked accuracy, as shown by the wide 95% CIs, Os teopenia and osteoporosis were found in 16.4% and 1% of the mothers, respec tively, In the subgroup defined by osteopenia or osteoporosis in the mother , lumbar spine bone mineral density was significantly higher in the daughte rs than in the mothers (0.994+/-0.095 g/cm(2) versus 0.895+/-0.098 g/cm(2); P<0.0001), whereas the opposite was true in the subgroup defined by normal bone mass in the mothers (1.068+/-0.110 g/cm(2) versus 1.109+/-0.098 g/cm( 2); P=0.0003). Nevertheless, lumbar spine bone mineral density was signific antly lower in the daughters of low-bone-mass women than in those of normal -bone-mass women (0.994+/-0.009 g/cm(2) versus 1.069+/-0.012 g/cm(2); P=0.0 006). These findings suggest a role of genetic factors inherited from the f ather and also indicate that bone mass gains during adulthood contribute to achievement of the optimal peak bone mass. In the family history study, bo ne mass was lower in the subjects with a family history of osteoporosis (12 3 of the 559 daughters, Z-scores normalized for height, weight, and puberta l status: bone mineral density Z-score, 0.054+/-1.104; bone mineral content Z-score, -0.014+/-1.079; 58 of the 275 mothers: bone mineral density, 1.04 8+/-0.107 g/cm(2); bone mineral content, 43.3+/-8.8 g) than in those withou t a family history of osteoporosis (438 daughters, bone mineral density Z-s core, 0.006+/-0.981; bone mineral content Z-score, -0.007+/-0.985; 217 moth ers: bone mineral density, 1.070+/-0.127 g/cm(2); bone mineral content, 43. 8+/-6.7 g); however, none of these differences were statistically significa nt. Conclusion. Our findings challenge the currently popular concept of mar ked bone mass heritability but are consistent with early genetic influences on lumbar spine bone mass. Thus, optimization of the peak bone mass acquir ed during growth may help to prevent osteoporosis.