The Incidence of Elevated Hemoglobin A_2 Levels in the American Negro

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Abstract
Five hundred samples of blood obtained from Negro subjects seen at the Washington University Clinic were screened by starch block electrophoresis for elevated amounts of hemoglobin A2. Four of the 500 had increased concentrations ranging from 4.0 to 6.0% of the total hemoglobin (normal range 1.5 to 3.3%). These 4 individuals had hematologic values commonly found in thalassemia trait. Thirteen per cent of the population studied had an electrophoretically demonstrable hemoglobin abnormality. In addition to the 4 with elevated hemoglobin A2, 43 had AS hemoglobin (8.6%), 12 had AC hemoglobin (2.4%), and 6 (1.2%) had hemoglobin A2 ("split" A2). From the data presented and from the reported incidence of sickle cell trait in St. Louis (9.4%) the following probabilities were calculated: approximately 1 in 500 of the Negro population can be expected to have sickle cell anemia, 1 in 5,000 sickle cell-thalassemia and 1 in 62,500 thalassemia major. However, reports of this last condition are rare in the American literature.