Delta Thalassemia: a Non-deletion Defect.

Hematological and gene mapping studies of two Southern Italian children doubly heterozygous for δ0-thalassemia and δ0β0-thalassemia have been carried out. No HbA2 was detectable by electrophoresis of total hemoglobin in these patients. Restriction enzyme analysis of the globin gene cluster with δ, γ, ∊ and RIH cloned probes showed all the expected normal bands, in addition to the abnormal fragments related to a previously described type of δ0β0-thalassemic deletion, demonstrating an apparently intact globin gene cluster on the thalassemic chromosome. The relevance of this finding to models for coordinated expression of non α globin genes is discussed. [ABSTRACT FROM AUTHOR]