Homozygosity or double heterozygosity for b-thalassemia results usually in a very severe anemia due to ineffective erythropoiesis and hemolysis, in which the pathology is caused by the lack of functional hemoglobin tetramers and by the large amount of free unstable a-globin chains.
Giordano, PC., et al. (1998). ‘Phenotype variability of the dominant beta-thalassemia induced in four Dutch families by the rare cd121 (G-->T) mutation’. Annals of Hematology 77(6):249-55. (RISCEN92)