Spectrum of α- and β-thalassemia variants in individuals with persistent microcytic hypochromia in Eastern Iran: implications for population genetic screening

Thalassemia (thal) is an inherited autosomal recessive disorder caused by mutations in the α- or β - globin genes, leading to reduced or absent globin chain synthesis in hemoglobin. This study aims to identify the mutations profiles of α- and β-thal among pre-marriage candidates with microcytic anemia in eastern Iran. A total of 7,440 individuals referred to the Birjand Health Center were evaluated for Premarital screening through using hematological parameters, including red blood cell (RBC) indices. Individuals diagnosed with iron deficiency anemia (IDA) received iron supplementation, whereas those who persistently exhibited microcytic hypochromic anemia with normal HbA 2 levels or elevated HbA 2 levels were referred for evaluation of α-thal and β-thal, respectively. Genotyping was done using Amplification-Refractory Mutation System Polymerase Chain Reaction (ARMS-PCR) and Gap Polymerase Chain Reaction (GAP-PCR). Among the study population, 8,9% ( n = 659) exhibited microcytic hypochromic based on red blood cell indices. Following Iron therapy, 6.4% ( n = 474) of individuals showed persistent anemia and iron treatment resistance and were subsequently evaluated using molecular genetic techniques for α- and β-thal variants. For the α-globin gene, HBA2 NG_000006.1.34164_37967del3804 (–α³·⁷) was the most prevalent variant, accounting for 34.3%, followed by HBA2 c.-2 A > G (5NT) (16.2%), a codon 19 variant (3.8%), and HBA2 NG_000006.1.34164_38564del4405 (–α⁴·²) (3.5%). For the β-globin gene, HBB c.92 + 5G > C [IVS-I-5 (G > C)] was the most frequent variant (43.3%), followed by HBB c.135delC [codon 44 (− C)] (13.3%), HBB c.17_18delCT [codon 5 (− CT)] (11.7%), HBB c.50 A > T [codon 16 (A > T)] (10%), HBB c.27_28insG [frameshift codons 8/9 (+ G)] (10%), and a codon 15 variant (5%). The identification of the spectrum of specific mutations underscores the need for expanded genetic screening and counseling in this population. These findings emphasize the importance of implementing effective public health strategies to manage and prevent microcytic hypochromic anemia in regions with a high prevalence of sanguineous marriage.