Distribution and frequency of β-thalassemia mutations in northwestern and central Greece

Objective: beta -Thalassemia is a common autosomal recessive disorder resulting from over 200 different mutations of the beta -globin genes. The spectrum of beta -thalassemia mutations in Greece has been previously described in the population of the capital city of Athens, or in beta -thalassemia patients having transfusion therapy. The aim of the present study was to identify the distribution of the most common beta -thalassemia mutations in the population of northwestern and central Greece.Methods: The data for this study were derived from a total of 1130 unrelated subjects including 46 beta -thalassemia major, three beta -thalassemia intermedia and 1081 carriers identified in our antenatal screening program. beta -Thalassemia mutations were identified by ARMS, DGGE and Reverse Dot Blot. Results: The most common mutation, IVS-I-110, is followed, in order of frequency, by the mutations Cd-39, IVS-I-1, IVS-II-1, Cd-6, IVS-I-6, IVS-I-5, IVS-II-745, Cd-5 and 44 bp del. IVS-I-110 and Cd-39 frequencies are similar with those found in other Balkan countries. Significant differences in regional distribution were observed. The results showed a clear drift of the distribution of the most frequent IVS-I-110 mutation in the south-north (29.4, 40.0, 44.6 and 61.7%) and the east-west axis (31.8 and 44.6%). Conclusions: Population screening and prenatal diagnosis are significantly facilitated by these data. Furthermore, the detailed distribution tables of beta -thalassemia mutations are essential for counseling and extraction of genetic diversity estimates for population genetic studies in other inherited disorders.