Globin Synthesis in Sideroblastic Anaemia I α AND β PEPTIDE CHAIN SYNTHESIS

S ummary . The in vitro synthesis of the α and β peptide chains of globin have been measured in 11 patients suffering from sideroblastic anaemia (four congenital and seven idiopathic acquired). In the I0 patients who were anaemic the findings were similar. The synthesis of the globin chains was found to be defective in two respects; firstly, synthesis was asynchronous with an apparent deficiency of the synthesis of α chains, and, secondly, a large proportion of both α and β chains synthesized were not associated with haem but were free in the cell in the form of αβ dimers. Addition of haem to the incubation mixture greatly stimulated the synthesis of both chains, removed the free dimer pool and appeared to stimulate a chain synthesis. The finding that a large proportion of the α and β chains synthesized are not associated with haem but are free within the cell as a dimer pool, is very strong evidence that the underlying defect in sideroblastic anaemia is haem deficiency. The defective synthesis of a chains relative to β chains is as yet unexplained but may account for the low haemoglobin A 2 associated with this condition.