First Report of α-Thalassemia Genotypes from Transcaucasia

Abstract Background: Transcaucasia is a geographical region located on the border of Eastern Europe and Western Asia including territories of Azerbaijan, Georgia and Armenia. The region has long been known for high incidence of thalassemia and previous studies reported the highest prevalence of β-thalassemia in Azerbaijan (AZE - 4-5%, GEO - 3%, ARM - 2%) and an overlapping mutation spectrum within the region. Nevertheless, the characteristic genotypes and mutation spectrum of less recognised α-thalassemia have not been reported by far. In this multicentre cross-sectional study, we analysed the genotypes of α-thalassemia patients from Azerbaijan as representative of the region. Methods: 45 patients diagnosed with HbH disease, β-thalassemia major with milder clinical manifestations or any other clinical condition with possible inheritance of α-thalassemia mutations were included in the study. Clinically significant deletions as well as point mutations located on the HBA1 and HBA2 genes were identified via reverse dot blot hybridization method. Results: From total 8 identified mutations, 20.5 kb (45.3%) and 3.7 kb (31.4%) deletions were the most prevalent. Accordingly, -α3.7 /-(α)20.5 genotype was identified in more than half of the patients with HbH disease (N=23). The most common point mutations were α2 Poly A-2 (HBA2:c.*96G>A) - 7.0%, α2 codon 142 [T>C] (HBA2:c.427T>C) - 4.7%, and α2 IVS-I 5nt del (HBA2: c.95+2_95+6delTGAGG) - 4.7%. Conclusion: Deletions with less severe clinical presentation comparing to point mutations accounted for the majority of the spectrum. The milder phenotype might be the reason why this disease has been undermined in the region by β-thalassemia. The spectrum of mutations were similar of the populations of neighbouring high incidence territories such as Iran and Turkey. Disclosures No relevant conflicts of interest to declare.