RESUMEN
In the Far East two types of alpha-thalassemia genes, namely alpha-thalassemia, (alpha-thal1), and alpha-thalassemia2 (alpha-thal2) exist. Definite diagnosis of the alpha-thal1 and alpha-thal2 traits is very difficult because their hematological findings are minimally abnormal or normal. This study attempts to characterize the heterozygotes by hemoglobin chain synthesis in reticulocytes from obligatory cases of the alpha-thal1 and alpha-thal2 traits. Twelve parents of babies with hemoglobin Bart's hydrops fetalis (obligatory alpha-thal1 trait) had the mean total radioactivity alpha/beta ratio of 0.76 +/- SD 0.04, while that of 7 normal controls was 1.06 +/- SD 0.04. The alpha/beta globin chain ratios of 16 cases, who were either parents or offspring of patients with hemoglobin H disease, were found to segregate into 2 groups, i.e. 0.78 +/- SD 0.03 (10 cases) and 0.9l1 and alpha-thal2 traits respectively. The hematological data of the first group showed definite hypochromic microcytic red cells, similar to those of the parents of the hydrops. The second group had significantly higher mean corpuscular hemoglobin than the first group, compatible with alpha-thal2 trait. Our globin chain synthesis study thus appears to be capable of discriminating normal, alpha-thal1 and alpha-thal2 traits.