Genetic and environmental correlations between bone geometric parameters and body compositions.

The purpose of this study was to determine the genetic and environmental correlations between weight, lean mass and bone geometric parameters (sub-periosteal diameter, W; cross-sectional area, CSA; cortical thickness, CT; section modulus, Z; and buckling ratio, BR) of femoral neck. The sample was composed of 512 Caucasian pedigrees, including 2667 females and 1822 males. Bivariate quantitative genetic analyses were performed to evaluate the genetic (rho(G)), environmental (rho(E)) and phenotypic (rho(P)) correlations between the study traits. Univariate genetic analyses showed that the heritabilities (h(2)) for bone geometric parameters were significant (P < 0.001) ranging from 0.50 to 0.60. The significant common household effects indicated the common environment shared by household members for W, CSA, CT, Z and BR (P < 0.05), but the magnitude was small compared with heritabilities. rho(E), rho(G) and rho(P) between bone geometric parameters and weight, lean mass were generally significant. Interestingly, lean mass showed both stronger genetic and environmental correlations with the bone geometric parameters than weight. In addition, according to the magnitude of correlation coefficients, the rho(G) between body compositions and bone geometric parameters were generally stronger than rho(E) (except for that between BR and body compositions). These data suggested that the geometric parameters of femoral neck are under strong genetic control. Furthermore, some common genetic and environmental factors are shared by bone geometric parameters and weight, lean mass. The results may help understand the intertwined relationships between bone metabolisms, mechanical loading and body compositions.