Familial resemblance of bone mineral density (BMD) and calcaneal ultrasound attenuation: The BMD in mothers and daughters study

The familial resemblance in bone mineral density (BMD) and calcaneal broadb and ultrasound attenuation (BUA) was examined in 207 mother-daughter pairs. Mothers were participants in the Study of Osteoporotic Fractures. Three gr oups of daughters were recruited based on their maternal history of "fractu re," "low BMD" without fracture (< 0.58 g/cm(2), t-score < -2.5), and "norm al BMD" without fracture (> 0.67 g/cm(2), t-score > -1.6), Data on other po tentially heritable factors known to influence BMD and BUA were also collec ted. BMD was measured at the hip, spine, whole body, and calcaneus, Calcane al BUA was assessed using the Walker-Sonix UBA 575, Total hip and femoral n eck BMD were significantly lower (5.0-8.0%, p < 0.017) among daughters, in particular premenopausal daughters, of mothers with established osteoporosi s ("fracture" or "low BMD") compared with daughters of mothers at lower ris k of osteoporosis ("normal BMD"), BUA did not differ across daughter groups . Lifestyle characteristics (dietary calcium, smoking, physical activity) w ere not highly correlated in mothers and daughters. Height, weight, and bod y composition were significantly correlated within mother-daughter pairs an d could be a potential mechanism by which BMD is inherited. Among pre- and postmenopausal daughters, heritability estimates ranged from 50-63% and 34- 48%, respectively. Heritability for calcaneal BUA (53%) was evident among p ostmenopausal daughters only. In conclusion, familial association in BMD wa s strongest among premenopausal daughters. Estimates of heritability sugges t that maternal BMD and BUA are important independent predictors of BMD and BUA among daughters, reinforcing the importance of prevention and early in tervention among women with a positive family history of osteoporosis.