Genetic And Environmental Correlations Between Bone Geometric Parameters And Body Compositions

Osteoporosis is an important health problem in the world. Low bone one mineral density (BMD) is a major risk factor of osteoporotic facture (OF), so it is used as the major surrogate phenotype for osteoporosis.. Bone structural properties (shape, size, as well as three-dimensional architecture) are also important for bone strength. Recently specific values of mechanical and geometric properties of bone [i.e., sub-periosteal diameter (W), section modulus (Z), cross-section area (CSA), cortical thickness (CT), endocortical diameter (ED) and buckling ratio (BR)] can be inferred from Dual energy X-ray absorptiometry (DXA) measurements for BMD and bone size. The present study have two aims: the first is to determine the genetic (p_G), environmental (p_E) and phenotypic (p_P) correlations between weight, lean mass and bone geometric parameters mentioned above of femoral neck by bivariate quantitative genetic analyses. The other is to test association and linkage between an XbaI polymorphism in estrogen receptor-a (ER~a) gene and a HindIII polymorphism in ostecalcin (BGP) gene with bone geometric parameters by transmission disequilibrium test (QTDT) program. 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 smallcompared with heritabilities. pE, pG and pp 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 pG between body compositions and bone geometric parameters were generally stronger than pE (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. For the QTDT analyses, we found evidence of nominally significant within-family association between the BGP Hindlll marker and ED. Moreover, we obtained significant results about linkage between ER~a Xbal marker and CSA, ED, CT and BR, and BGP Hindlll marker and BR as well.