Characterization of nondeletion α‐thalassemia mutations in the Greek population

α‐Thalassemia is usually due to deletions within the α‐globin gene cluster, leading to loss of function of one (‐α) or both [‐(α) or –] α‐globin genes. Nondeletion mutations (denoted αα T or α T α) are less frequent and in Greece are not well defined. We report the analysis of 16 nondeletion α‐thalassemia chromosomes using a polymerase chain reaction method to amplify specifically the α2‐globin gene, which was subsequently screened using ASO hybridization or restriction enzyme analysis for four mutations already characterized in other Mediterranean and Middle Eastern populations. Of the 16 nondeletion chromosomes, nine had the polyadenylation signal mutation (α PolyA α), two the IVSI 5′ pentanucleotide deletion (α Hph α), two the Hb Icaria mutation (α ic α), and one the initiation codon mutation (α Nco α). In two, the defects are still undefined. These findings show that nondeletion α‐thalassemia in Greece is heterogeneous and that the most frequent mutation (accounting for >50%) is the polyadenylation signal mutation, which to date was most commonly found in the Saudi Arabian population. © 1993 Wiley‐Liss, Inc.