A study has been made of the structure and synthesis of hemoglobins in a 53-yr-old black male who expresses homozygous β-thalassemia mildly. His hemoglobin has about 40% Hb-A, 50% Hb-F, and 10% Hb-A2. The β and δ chains of his Hb-A and Hb-A2 have been shown by detailed study to have a normal amino acid composition of the tryptic peptides. Decreased production of β chains relative to α chains occurs as is commonly observed in β-thalassemia. Differential centrifugation of erythrocytes and bone marrow reveals a marked difference in hemoglobin composition; the percentage of Hb-A2 is increased and that of Hb-F is decreased in cells of lower density. The ratio of Gγ to Aγ chains is about 3:2 in the Hb-F of centrifugally separated cells or in bone marrow.
Similar, but less extensive, studies have been made on two black females (ages 23 and 54) whose clinical course has approximated that of the index case.