The Incidence of Elevated Hemoglobin A2 Levels in the American Negro

HEMOGLOBIN A2 is PRESENT in a concen-tration of less than 3.3 per cent of the total hemoglobin in all normal adults (1). Elevation above this level is known to accompany the erythrocyte abnormali-ties seen in classical thalassemia trait (1, 2). Whereas thalassemia major has rarely been described in the American Negro, many cases of sickle cell thalassemia have been reported in this race (summarized by Dacie (3)). I t seemed of interest, therefore, to screen a random popula t ion of Negroes for an exact estimate of the prevalence of ele-vated hemoglobin A2 values. T h e results obtained revealed an increased amount of hemoglobin A2 in 4 out of 500 hemolysates screened by starch block electrophoresis, an incidence of 0.8 per cent. These 4 persons had hematologic values commonly found in individuals with thalassemia trait. MATERIALS AND METHODS Five milliliters of blood anticoagulated with ethylenediamine-tetra-acetic acid (EDTA) were obtained from 500 consecutive Negro patients who had samples drawn at the diagnostic lab-oratory of the Washington University Clinics. Hemolysates were prepared by the method