Summary
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.
Keywords Admixture mapping - Body composition - Genetic ancestry - Linkage analysis - Osteoporosis - Single nucleotide polymorphisms (SNPs)