Estimates of European American Ancestry in African Americans Using p.C282Y.

p.C282Y (chromosome 6p22.2; exon 4, c.845G>A; rs1800562), a hemochromatosis-associated polymorphism in European Americans, is absent in sub-Saharan West African blacks. We estimated European American ancestry in African Americans () using published p.C282Y allele frequencies of sub-Saharan West African blacks; and ≥50 unselected African Americans and ≥50 unselected European Americans in the same city/region. p.C282Y allele frequency in 870 West African blacks (The Gambia, Ghana, Nigeria, Senegal, Sierra Leone) was 0.0000 (confidence interval [95% CI 0.0000-0.0027]). p.C282Y allele frequencies in European Americans were 0.0600 (12,592 participants; five single-site studies) and 0.0673 (54,882 participants; two multisite studies). p.C282Y allele frequencies in African Americans were 0.0102 (3084 participants; five single-site studies) and 0.0122 (30,762 participants; two multisite studies). for all data was 0.1803 (standard error 0.0049; [95% CI 0.1706-0.1900]). City/region estimates of differed 1.8-fold: 0.1321, Rochester, NY; 0.1456, Birmingham, AL; 0.1569, Upper Savannah Region, SC; 0.1612, Portland, OR; 0.1746, San Diego, CA; 0.1780, Hartford, CT; 0.1957, District of Columbia; 0.2377, Oakland, CA; and 0.2429, Irvine, CA. Estimates of using p.C282Y are consistent with those using other autosomal markers, differ across nine cities/regions, and reflect paternal and maternal contributions of European American ancestry in African Americans.