The research utility of the GRS is likely limited to samples of European descent. GRS-BMI and GRS-obesity associations in African American ARIC participants were much smaller than comparable associations in white ARIC participants. Although the sample included fewer African Americans than whites, power to detect effects of equal size to those observed in whites was well over 80% in the African American sample. Moreover, effect-size measures (r, R2, relative risk, AUC, IDI) showed little evidence that the GRS predicted BMI or obesity among African Americans. These results suggest caution in using GWAS of European-descent populations to derive GRSs for African Americans. Our analyses indicated the GRS performed similarly among men and women. However, emerging evidence for gene-sex interactions in obesity 46,47 suggests that future obesity GRSs may require sex-specific construction.
