Distribution of transferin saturations in the African-American population

Abstract

To determine if transferin saturations in African American may reflect the presence of a gene that influences iron metabolism, we analyzed the distribution of these values in 808 African Americans from the second National Health and Nutrition Survey. We tested for a mixture of three normal distributions consistent with population genetics for a major locus effect in which the proportion of normal homozygotes is p2; of heterozygotes, 2pq; of affected homozygotes, q2; and in which p+q = 1. Three subpopulations based on transferrin saturation were present (P < .0001) and the fit to a mixture of three normal distributions was good (P = .2). A proportion of .009 was included in subpopulation with a mean ± standard deviation transferin saturation of 63.4% ± 5.7% (postulated homozygoted for a gene that influences iron metabolism), while a proportion of .136 had an intermediate saturation of 38.0% ± 5.7% (postulated normal homozygotes). These proportions were consistent with population genetics because the sum of the square roots of the .925) and the highest (q = 0.093) was approximately 1 (1.018). The results are consistent with the presence in African Americans of a common locus that influences iron metabolism.