Genetic ancestry and body composition

Nothing too earth shattering here.. another study showing that in African Americans, European ancestry correlates positively with lower BMD (bone mass density) --although this correlation was much more pronounced among women, longer trunk length, shorter leg length, and increased body fat.
The conclusion in the abstract is good: "These results indicate that some population differences in body composition may be due to population-specific allele frequencies, suggesting the utility of admixture mapping for identifying susceptibility genes for osteoporosis, sarcopenia, and obesity."

Genetic markers for ancestry are correlated with body composition traits in older African Americans

Osteoporos Int. 2007 Jan 18

Shaffer JR, Kammerer CM, Reich D, McDonald G, Patterson N, Goodpaster B, Bauer DC, Li J, Newman AB, Cauley JA, Harris TB, Tylavsky F, Ferrell RE, Zmuda JM; for the Health ABC study.

Abstract: Individual-specific percent European ancestry was assessed in 1,277 African Americans. We found significant correlations between proportion of European ancestry and several musculoskeletal traits, indicating that admixture mapping may be a useful strategy for locating genes affecting these traits. INTRODUCTION: Genotype data for admixed populations can be used to detect chromosomal regions influencing disease risk if allele frequencies at disease-related loci differ between parental populations. We assessed evidence for differentially distributed alleles affecting bone and body composition traits in African Americans. METHODS: Bone mineral density (BMD) and body composition data were collected for 1,277 African and 1,790 European Americans (aged 70-79). Maximum likelihood methods were used to estimate individual-specific percent European ancestry for African Americans genotyped at 37 ancestry-informative genetic markers. Partial correlations between body composition traits and percent European ancestry were calculated while simultaneously adjusting for the effects of covariates. RESULTS: Percent European ancestry (median = 18.7%) in African Americans was correlated with femoral neck BMD in women (r = -0.18, p < 10−5) and trabecular spine BMD in both sexes (r = −0.18, p < 10−5) independently of body size, fat, lean mass, and other covariates. Significant associations of European ancestry with appendicular lean mass (r = −0.19, p < 10−10), total lean mass (r = −0.12, p < 10−4), and total body fat (r = 0.09, p < 0.002) were also observed for both sexes. Conclusions These results indicate that some population differences in body composition may be due to population-specific allele frequencies, suggesting the utility of admixture mapping for identifying susceptibility genes for osteoporosis, sarcopenia, and obesity.