Evaluation of Beta Globin Gene Mutations in Mersin, Turkey: A Single Center Experience

Beta-thalassemia is the most common single gene disease worldwide with an autosomal recessive inheritance caused by the deficiency or absence of β-globin chain synthesis. The aim of our study is to evaluate the types and frequencies of mutations in patients diagnosed with beta thalassemia in the province of Mersin. Clinical data of 292 patients who underwent hemoglobinopathy screening at Mersin University Faculty of Medicine Hospital between 2017 and 2019 were retrospectively analysed. Of the 292 patients with mutations in the HBB gene, 55.5% (n=162) had beta thalassemia. In patients with beta thalassemia, 32 different mutations, including 4 abnormal Hb variants, and 12 different compound heterozygous β-tal mutations were detected in 22 of these patients. The most commonly seen allele was c.93-21G>A with a frequency of 25.2%. The most common compound variation was HBB:c.*233G>C/HBB:c.92+6T>C/A, (27.4%). We detected the mutation HBB:c.92+5G>A, which has not been previously reported in Turkey. The types and frequencies of beta-thalassemia mutations vary among geographic regions. This study examined the prevalence of beta-thalassemia mutations at the molecular level and enhanced the detection rate of unidentified mutations by DNA sequence analysis. Identification of new mutations in beta-thalassemia is useful for genetic counseling, prenatal diagnostic, screening programs, and literature.