Within- and Across-Sex Inheritance of Bone Microarchitecture.

Context The maternal heritability of bone microarchitecture according to the sex of the offspring is not known. Objective To explore sex difference and influence of mother's 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 bone mineral density (BMD) and bone microarchitecture were measured at the distal radius and tibia by high-resolution peripheral quantitative computed tomography. A principal components analysis 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 (½h2) was estimated as the slope of the regression between offspring and mothers for each bone parameter separately. Results The mean age (± standard deviation) of mothers and daughters was 50.6 ± 4.1 years and 20.4 ± 0.5 years, respectively; that of mothers and sons was 45.8 ± 3.9 years and 15.2 ± 0.5 years, respectively. Most trabecular and cortical parameters were inherited in both mother-daughter and mother-son pairs (β = 0.15 to 0.33; P = 0.05 to 0.001). At the tibia, trabecular and cortical principal components were significantly inherited in both sexes, whereas only the trabecular one was inherited at the radius (½h2, 21% to 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 (½h2, 9% to 25%). In the mother-daughter 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.