A novel Mediterranean "delta beta-thalassemia" determinant containing the delta (+) 27 and beta (0) 39 point mutations in cis.

The term delta beta-thalassemia with normal HbF has been recently proposed to define heterogenous delta and beta globin gene molecular defects involving the same chromosome in cis. Here, we describe a Sardinian family in which three members showing microcytosis, border-line HbA2 levels and normal HbF proved to be heterozygotes for delta(+) 27 and beta(0) 39 point mutations in cis by allele specific oligonucleotide hybridization as well as by ECO 0 109 I endonuclease digestion and electrophoresis. As some of these beta-thalassemia carriers shows normal HbA2 levels, knowledge of the molecular basis of this novel delta beta-thalassemia silent phenotype would be useful in thalassemia screening and genetic counselling.