The Assess Of Trunk Obesity And Bivariate Whole-genome Linkage Scan Between Fat Mass And Bone Geometric Parameters

Obesity is a serious health problem characterized byexcess body fat. It is associated with an increased risk ofmetabolic diseases, and the Chinese trended to trunk obesity,Therefore, the early prevention of trunk obesity has importanthealth significance. One of the aims for this study is to assessthe validity of anthropometric indices as screening thepredictors of trunk obesity in young Chinese adults, werecruited 1946 (853 women, 1093 men) healthy Chinese volunteersaged 20-40 years. Trunk fat mass was measured by dual-energyX-ray absorptiometry. Body mass index (BMI), waistcircumference (WC), waist-to-hip ratio (WHR) and conicityindex (C index) were measured or calculated. Receiver operatingcharacteristic (ROC) curves were used to compare the validityof each anthropometric index to predict trunk adiposity and todefine the best cutoffs. BMI, WC, WHR and C index were allsignificantly and positively correlated with trunk fat mass inboth men and women, Correlations between trunk fat mass withBMI and WC were higher than those between trunk fat mass andeither WHR or C index. BMI and WC performed better as theanthropometric indices defining trunk obesity than WHR and Cindex. Suggested cutoffs of BMI and WC to define trunk obesitywere 23.3kg/m~2, 81.1cm in men and 21.1 kg/m~2, 68.7cm in women,respectively.Obesity and osteoporosis are two highly related complexdiseases, osteoporosis is characterized by reduced bone massand increased risk of low trauma fractures, Bone mineraldensity (BMD) and femoral neck genomic parameter (FNGP) are twomain measures for osteoporosis. Body fat mass (BFM) and femoral neck geometric parameters (FNGPs), as the respective importantrelated phenotypes for obesity and osteoporosis, arephenotypically correlated. However, how the genetic factorsaccount forthe phenotypic correlations is unknown. To quantifythe genetic correlations between BFM and FNGPs [were crosssectional area (CSA), cortical thickness (CT), endocorticaldiameter (ED), sectional modulus (Z) and breaking ratio (BR)]and, if possible, to detect the specific genomic regions sharedby them, bivariate genetic analysis and bivariate whole-genomelinkage scan (WGLS) in 4498 Caucasian individuals from 451families were performed within each pair of the studiedphenotypes. All the study phenotypes are significantlycontrolled by genetic factors with the heritabilies of0.45-0.68. Significantly positive genetic correlations werefound between BFMand CSA, W, Z and CT except between BFM andBR. 6p25 has complete pleiotropic effects on the variations ofBFMand Z (p1＜0.0.01, p2=0.36) in the female sub-population,6q27 (p1=0.013, p2＜0.01) and 17q11(p1=0.02, p2＜0.01) havecoincident linkages for BFM & CSA and BFM & Z in the entirepopulation. The moderate genetic correlations and severalshared genomic regions for BFM and FNBPs were identified here.This may increase the understanding on the complex mechanismunderlying the correlation between obesity and osteoporosis.