beta+-Thalassemia intermedia with low HbF.

Two cases of homozygous beta+-thalassemia intermedia have been detected in a Brazilian family of Portuguese and German extraction. The patients are 39 and 43 years old, showed a normal somatic and sexual development and had been transfused only occasionally. Red blood cell morphology was similar to that of thalassemia major, but they had unusually low levels of HbF (5.0% and 6.8%). Globin chain synthesis measured in reticulocytes was in the same range as other beta-thalassemia homozygotes. One or both genes in this family must be a particularly mild beta-thalassemia allele, despite the fact that the heterozygote members of the family presented clinical, hematological, and biochemical features indistinguishable from the typical heterozygotes for the beta-thalassemia trait with high HbA2.