A novel mediterranean “δβ‐thalassemia” determinant containing the δ + 27 and β°39 point mutations in cis

The term δβ‐thalassemia with normal HbF has been recently proposed to define heterogenous δ and β globin gene molecular defects involving the same chromosome in cis. Here, we describe a Sardinian family in which three members showing microcytosis, border‐line HbA 2 levels and normal HbF proved to be heterozygotes for δ + 27 and β°39 point mutations in cis by allele specific oligonucleotyde hybridization as well as by ECO 0 109 I endonuclease digestion and electrophoresis. As some of these β‐thalassemia carriers shows normal HbA 2 levels, knowledge of the molecular basis of this novel δβ‐thalassemia silent phenotype would be useful in thalassemia screening and genetic counselling. © 1994 Wiley‐Liss, Inc.