Genetic heterogeneity of beta thalassemia mutations in Kahramanmaraş province in Southern Turkey: preliminary report

Background: Beta thalassemia is one of the most common autosomal single-gene disorders in the world. The prevalence of the disease is in the “thalassemia belt” which includes the Mediterranean region of Turkey; throughout the country the gene frequency is estimated to be 2.1%, but in certain regions, this figure increases to 10%.Aim: In this first study, we aimed to determine the frequency of β-thalassemia trait and distrubition of mutations in Kahramanmaraş province, which is located in the southern part of Turkey.Materials and Methods: In this study; 5 ml blood samples was taken from 14 thalassemic patients and their relatives who were taking care of Sutcu Imam University Hospital at Kahramanmaraş. Also, we collected blood samples from 245 adults for screening beta thalassemia trait. Haematological data were obtained by cell counter.  HbA2 was determined by HPLC. Ten common mutations were screened by ARMS  (Amplification Refractory Mutation System) method. These β-thalassemia mutations are -30 (T>A), Fsc8 (-AA), Fsc8/9 (+G), IVS1-1 (G>A), IVS1-5 (G>C), IVS1-6 (T>C), IVS1-110 (G>A ), Cd 39 ( C>T), IVS2-1 (G>A), IVS 2-745 (C>G). A rare mutation; Fsc44 (-C) was charecterized by DNA sequencing.Results: Ten patients were detected as homozygous for IVS1-110 (seven cases), Fsc 44 (two cases) and IVS1-5 (only one case). Rest of the 4 patients were double heterozygous (two: IVS1-110/IVS1-6, one: Fsc8/Fsc8-9, one: IVS2-1/IVS1-5). In 245 adult, five  β-thalassemia trait were detected by screening survey. Conclusion: Sixteen alleles were detected as IVS1-110 in 57.1%. It was seen the most common mutation in Kahramanmaraş. Seven different β-thalassemia mutations were found in this study. Each of 10 families have only one thalassemic patient, other two families have double thalassemic patient in total 12 family.