Genetic and environmental correlations between XXXX phenotypes and age at menarche.

@entity1 @entity28
OBJECTIVE: To assess the extent that the genetic and environmental factors contribute to the phenotypic correlations between @entity28 traits and age at menarche (AAM), and also to examine the influence of AAM on @entity28 in both pre- and postmenopausal @entity1 . METHODS: F ive hundred and twelve pedigrees with 2667 Caucasian female subjects from two to four generations were recruited. Fat mass and lean mass (both in kg) were measured by dual-energy X-ray absorptiometry scanner. Body mass index (BMI) (kg/m(2)) was calculated. We performed bivariate quantitative genetic analyses in the total sample containing 2667 Caucasian @entity1 . We also selected 206 unrelated premenopausal @entity1 and 140 unrelated postmenopausal @entity1 from the total sample, and computed the respective phenotypic correlation between @entity28 and AAM in these two subgroups. RESULTS: For fat mass, lean mass and BMI, we detected their significant negative genetic correlations with AAM after adjustment for significant covariates, which were -0.3170 (P<0.001), -0.1721 (P<0.05) and -0.3665 (P<0.001), respectively. However, their environmental correlations with AAM were all nonsignificant (P>0.05), ranging from -0.0016 to 0.0192. In the premenopausal subgroup, significant associations were observed between fat mass and AAM (rho=-0.231, P<0.01) as well as between BMI and AAM (rho=-0.257, P<0.01). In the postmenopausal subgroup, no such associations were observed. CONCLUSION: Our results for the first time suggested that significant phenotypic association between @entity28 phenotypes and AAM is mainly attributable to shared genetic rather than environmental factors, and AAM may have stronger effects on @entity28 phenotypes in pre- than in postmenopausal @entity1 .
