Genetic and environmental influences on skeletal muscle phenotypes as a function of age and sex in large, multigenerational families of African heritage.
The aim of this study was to estimate the heritability of and environmental contributions to skeletal muscle phenotypes (appendicular lean mass and calf muscle cross-sectional area) in subjects of African descent and to determine whether heritability estimates are impacted by sex or age. Body composition was measured by dual-energy X-ray absorptiometry and computed tomography in 444 men and women aged 18 yr and older (mean: 43 yr) from eight large, multigenerational Afro-Caribbean families (family size range: 21-112). Using quantitative genetic methods, we estimated heritability and the association of anthropometric, lifestyle, and medical variables with skeletal muscle phenotypes. In the overall group, we estimated the heritability of lean mass and calf muscle cross-sectional area (h(2) = 0.18-0.23, P < 0.01) and contribution of environmental factors to these phenotypes (r(2) = 0.27-0.55, P < 0.05). In our age-specific analysis, the heritability of leg lean mass was lower in older vs. younger individuals (h(2) = 0.05 vs. 0.23, respectively, P = 0.1). Sex was a significant covariate in our models (P < 0.001), although sex-specific differences in heritability varied depending on the lean mass phenotype analyzed. High genetic correlations (rho(G) = 0.69-0.81; P < 0.01) between different lean mass measures suggest these traits share a large proportion of genetic components. Our results demonstrate the heritability of skeletal muscle traits in individuals of African heritage and that heritability may differ as a function of sex and age. As the loss of skeletal muscle mass is related to metabolic abnormalities, disability, and mortality in older individuals, further research is warranted to identify specific genetic loci that contribute to these traits in general and in a sex- and age-specific manner.
Division of Gerontology, University of Maryland School of Medicine, and Baltimore Geriatric Research, Education and Clinical Center, Veterans Affairs Maryland Health Care System, Baltimore, MD 21201, USA. sprior@grecc.umaryland.edu
Steven J
SJ
Prior
Stephen M
SM
Roth
Xiaojing
X
Wang
Candace
C
Kammerer
Iva
I
Miljkovic-Gacic
Clareann H
CH
Bunker
Victor W
VW
Wheeler
Alan L
AL
Patrick
Joseph M
JM
Zmuda
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People / Q000208:ethnology / Q000235:genetics*; D001823:Body Composition / Q000235:genetics; D001837:Body Weights and Measures; D004777:Environment; D005190:Family / Q000208:ethnology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D020412:Multifactorial Inheritance; D018482:Muscle, Skeletal / Q000502:physiology*; D010641:Phenotype; D019655:Quantitative Trait, Heritable; D012727:Sex Characteristics; D014300:Trinidad and Tobago / Q000208:ethnology