Genotype/Phenotype Correlation of β-Thalassemia in Syrian Patients: A Cross-Sectional Study

β-Thalassemia (β-thal) is an inherited blood disorder caused by reduced or absent synthesis of β-globin chains leading to imbalance of globin chain synthesis. β⁰-Thalassemia (β⁰-thal), refers to the complete absence of β-globin chain production on the affected allele. β⁺-Thalassemia (β⁺-thal) refers to alleles with some residual production of β-globin chain. We studied the correlation of genotype/phenotype of β-thal disease in Syrian patients. A cross-sectional study was carried out on 260 patients with β-thal. Genotyping was determined by a DNA sequencing technique. Routine investigations were performed to assess the complete blood count (CBC), serum ferritin, Hb A₂ and Hb F levels. We found that the β⁰/β⁰ genotype was the most common in our patients followed by β⁺/β⁺ and β⁰/β⁺. Patients with β⁰/β⁰ received transfusions at an earlier age and more frequently when compared to those with β⁰/β⁺ and β⁺/β⁺ genotypes. Moreover, patients with β⁰/β⁰ had higher levels of Hb F and lower levels of Hb A₂ compared to those with β⁰/β⁺ and β⁺/β⁺ genotypes. All patients with β-thal intermedia (β-TI) carry the β⁺/β⁺ genotype, while all patients with β⁰/β⁰ and β⁰/β⁺ genotypes presented with transfusion-dependent β-thal major (β-TM).