?-Globin loci in homozygous ?-thalassemia intermedia

Abstract
Homozygous β-thalassemia intermedia (TI) differs from thalassemia major (TM) in being less severe clinically. Associated α-thalassemia could account for the TI phenotype by reducing the α/non-α chain imbalance. We have analyzed the α loci of 9 TI and 11 TM patients by restriction endonuclease mapping. All the TM and 7 of the TI patients have the normal complement of four α-globin genes (αα/αα). One TI patient has three α-globin genes (αα/-α), and another TI patient, has five α genes (αα/ααα).