alpha-Thalassemia: prevalence and hematologic findings in American Blacks

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Abstract
.alpha.-Thalassemia is common in Southeast Asia and the Mediterranean, where the predominant lesion seems to be a deletion of 1 or more of the 4 gene loci responsible for .alpha.-globin chain production. In the USA, the prevalence of .alpha.-thalassemia in blacks was once thought to be low, but more recent studies showed that the prevalence of .alpha.-thalassemia is high. The globin chain synthetic ratios in 144 black Americans were measured to determine the prevalence and hematologic manifestations of .alpha.-thalassemia in this population. There were 120 subjects with a mean synthetic ratio of 0.986 .+-. 0.04, with a range of 0.90 to 1.06; these were classified as normal. Five subjects had .beta.-thalassemia; 19 subjects had mild .alpha.-thalassemia. The overall gene frequency for .alpha.-thalassemia was estimated to be 0.07 in this population. The Hb values of subjects with mild .alpha.-thalassemia were not statistically significantly different from normal black or white control subjects of the same sex, but there was a significant decrease in the mean corpuscular volume and in the mean corpuscular Hb value.