Associations between maternal peak bone mass and bone mass in prepubertal male and female children

The aim of this study was to estimate heritability of bone density in preme nopausal women, prepubertal male, and prepubertal female child pairs. We st udied 291 pairs (mothers, mean age, 33 years, range 22-45 Sears; children, mean age, 7.92 years, range 7.32-8.92 years). Bone density and body composi tion were assessed by dual-energy X-ray absorptiometry. Height and weight w ere measured in both mother and child. Body size-adjusted heritability esti mates for areal bone density (g/cm(2)) were all statistically significant ( femoral neck, 59%; lumbar spine, 38%; total body, 41%) and were consistentl y and significantly higher in mother-daughter pairs (n = 105) as compared w ith mother-son pairs (n = 186). Heritability estimates for bone mineral app arent density (BMAD; g/cm(3)) were marginally lower but remained statistica lly significant at all sites (femoral neck, 51%; lumbar spine, 32%; total b ody, 38%). Maternal osteopenia was associated with significant reductions i n bone mass at all sites in the children (femoral neck, 0.75 SD and p < 0.0 001; lumbar spine, 0.61 SD and p < 0.0001; total body, 0.43 SD and p = 0.01 2). Mother-child bone areal bone density correlation coefficients and predi ction of low bone mass in the child were greater (but this did not reach st atistical significance) if the corresponding anatomical site in the mother was used for prediction with the exception of the total body. These data co nfirm that heritability of bone mass extends to prepubertal children and is gender- and possibly site-specific as well as under separate genetic contr ol to growth. Furthermore, the strength of the mother-child association is such that bone density screening of mothers would make it possible to ident ify most prepubertal children at higher risk of osteoporosis in later life.