Within and across-sex inheritance of bone micorarchitecture

Context: The maternal heritability of bone microarchitecture according to the sex of the offspring is not known. Objective: To explore gender difference and influence of mother menopausal status on the heritability of bone microarchitecture between mothers and their offspring. Subjects and Methods: In 102 mother-daughter and 161 mother-son pairs, volumetric BMD and bone microarchitecture were measured at distal radius and tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT). A principal components analysis (PC) was applied for the radius and the tibia volumetric BMD and microarchitecture parameters separately. Two components, a trabecular one and a cortical one were identified at the radius and tibia. Half heritability (1⁄2h2) was estimated as the slope of the regression between offspring and mothers for each bone parameter separately. Results: Themeanage of mothersanddaughterswas50.64.1 yrsand20.40.5 yrs,andof mothers and sons 45.83.9 yrs and 15.20.5 yrs, respectively. Most trabecular and cortical parameters were inherited in both mother-daughter and mother-son pairs (Beta0.15–0.33, p0.05–0.001). At tibia, trabecular and cortical PCs were significantly inherited in both sexes, while only trabecular one was inherited at radius (1⁄2h221%-35%). There was no difference in heritability of bone microarchitecture between mother-daughter and mother-son pairs. All heritabilities remained after adjustment for age, weight, height, gonadal status and areal BMD (1⁄2h29%-25%). In the motherdaughter pairs, there was no systematic drop of heritability across menopause. Conclusions: Volumetric bone density and microarchitecture are highly and similarly inherited between and within sexes. The genetic effects remain predominant across menopause.