Distribution of transferrin saturations in the African-American population.
To determine if transferrin saturations in African Americans 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 a subpopulation with a mean +/- standard deviation transferrin saturation of 63.4% +/- 5.7% (postulated homozygotes for a gene that influences iron metabolism), while a proportion of .136 had an intermediate saturation of 38.0% +/- 5.7% (postulated heterozygotes) and .856 a saturation of 24.6% +/- 5.7% (postulated normal homozygotes). These proportions were consistent with population genetics because the sum of the square roots of the proportions with the lowest mean transferrin saturation (P = .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.
Gordeuk
V R
VR
Department of Medicine, The George Washington University Medical Center, Washington D.C., USA.
McLaren
C E
CE
Looker
A C
AC
Hasselblad
V
V
Brittenham
G M
GM
D000328:Adult; D000349:Africa / Q000453:epidemiology / Q000208:ethnology; D000368:Aged; D044383:Black People / Q000235:genetics*; D004032:Diet; D004198:Disease Susceptibility; D005260:Female; D005828:Genetics, Population; D005838:Genotype; D006306:Health Surveys; D006432:Hemochromatosis / Q000453:epidemiology / Q000235:genetics; D006801:Humans; D007501:Iron / Q000097:blood*; D019190:Iron Overload / Q000453:epidemiology / Q000208:ethnology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D014168:Transferrin / Q000378:metabolism*; D014481:United States / Q000453:epidemiology; D044465:White People / Q000235:genetics; D001741:Black or African American
D014168:Transferrin; D007501:Iron