ALPHA-THALASSEMIA IN AMERICAN BLACKS - STUDY OF A FAMILY WITH 5 CASES OF HEMOGLOBIN-H DISEASE

Summary. Five cases of HbH disease were discovered in a large family of American Blacks. Anaemia was mild with PCV ranging from 0.275 to 0.405. The amount of HbH was 2–6%. Studies of haemoglobin synthesis in peripheral blood reticulocytes demonstrated marked deficits in α globin production with an average α/β ratio of 0.31 (range 0.22–0.36). Eighteen additional family members had evidence of thalassaemia trait and were provisionally classified as either α‐that‐1 (average MCV of 65.2 fl; range 59–70) or α‐thal‐2 (average MCV 79.6 fl; range 74–88). A subject with α‐thal‐1 trait had an α/β ratio of 0.56; the average for five cases of α‐thal‐2 was 0.73. One other family member was thought to be homozygous for α‐thal‐2 trait and exhibited an MCV of 65 fl with an α/β ratio of 0.5. These data reconfirm that in Blacks with α thalassaemia the proportion of HbH is lower and the severity of anaemia is less than in certain other racial groups, e.g. Southeast Asians. However, the degree of hypochromia and microcytosis and the imbalance in α and β globin synthesis appear to be similar in Blacks and other races. These results suggest that the milder clinical course of HbH disease in Blacks is not a result of greater α globin production in that population of thalassaemics. Copyright © 1979, Wiley Blackwell. All rights reserved