Heritability of blood concentrations of sex-steroids in relation to body composition in young adult male siblings.
OBJECTIVE
Sex steroid concentrations in men are related to body composition and both are determined by genetic and environmental factors. This study investigates heritability estimates of sex steroid serum concentrations and body composition as well as the genetic and environmental components of their interrelation.


METHODS
Six hundred and seventy-four men (25-45 years) were included in this study with 274 independent pairs of brothers.


METHODS
Body composition and regional fat mass estimates were determined using dual-energy X-ray absorptiometry. Serum testosterone (T), SHBG, oestradiol (E(2)) and LH levels were determined by immunoassay; free T and E(2) levels were calculated.


RESULTS
Both sex steroid hormone concentrations and indices of body composition exhibited significant heritability estimates. Among sex steroid hormones, T had the highest heritability (h(2) = 0.65), followed by free T (h(2) = 0.54). A heritability of 0.73 was observed for SHBG; a heritability estimate of 0.83 was obtained for body weight. Significant genetic correlations were found between whole body fat mass and serum T (rho(G) = -0.46), free T (rho(G) = -0.27) and SHBG (rho(G) = -0.48) concentrations. No genetic relationship was observed between total (F) E(2) or LH concentrations, respectively, and body composition.


CONCLUSIONS
Both sex steroid serum levels and body composition are under strong genetic control. Their interrelation is in part underlied by a genetic correlation, indicative of the action of shared genes.
Bogaert
Veerle
V
Department of Endocrinology, Ghent University Hospital, Belgium.
Taes
Youri
Y
Konings
Peter
P
Van Steen
Kristel
K
De Bacquer
Dirk
D
Goemaere
Stefan
S
Zmierczak
Hans
H
Crabbe
Patricia
P
Kaufman
Jean-Marc
JM
D000273:Adipose Tissue / Q000033:anatomy & histology; D000328:Adult; D001823:Body Composition / Q000235:genetics*; D015992:Body Mass Index; D016022:Case-Control Studies; D004777:Environment; D012739:Gonadal Steroid Hormones / Q000097:blood* / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D035781:Siblings
D012739:Gonadal Steroid Hormones