δβ-Thalassemia in a Mexican Family: Clinical Differences Among Homozygotes

Abstract

Three →β-thalassemia homozygotes were found in a Mexican family. Both parents and two siblings had heterozygous 63-thalassemia with about 10% Hb F, mild microcytosis and mild hypochromia, while three siblings were normal. Hb F, which was the only Hb component in the homozygotes, had equal quantities of Gγ and Aγ chains as in GγAγ-→β-thalassemia. The homozygotes had comparable erythrocytic indices which were about the same as those of the heterozygotes. However, two were clinically and hematologically healthy but the third had a severe chronic hemolytic anemia and a more severe in vitro chain synthesis imbalance than her homozygous sisters. Comparison of these cases with other GγAγ 63-thalassemia homozygotes and with GγAγ HPFH homozygotes indicates the possibility that the proliferation of F-cell precursors may be defective in →β-thalassemia.