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

Abstract

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).

Keywords:

• β-Thalassemia (β-thal)
• correlation
• genotype phenotype
• mutation; Syria

Acknowledgments

We thank Professor M. Kabakebi, the president of Damascus University, Professor I. Othman, the Director General of the Atomic Energy Commission of Syria (AECS) and Professor A.H. Natoof, dean of Faculty of Pharmacy at Damascus University, Damascus, Syria for their support. We also thank the medical and laboratory staff of the National Thalassemia Center in Damascus, Syria for their help and guidance.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Additional information

Funding

We thank the Faculty of Pharmacy, Damascus University, Damascus, Syria for their financial support.