Determination of TAL1 expression and its relationship with HbF level in beta-thalassemia major patients

Objective: Hemoglobinopathies are the most common single gene diseases seen in the world. For beta-thalassemia, which is one of the hemoglobinopathies, the increase of fetal γ-globin expression in the postnatal period is one of the modifying factors and decreases the symptoms of the disease. In this context, the aim of our project is to investigate the relationship between the expression of the transcription factor TAL1 that regulates the gamma globin promoter region and HbF elevation in beta-thalassemia major patients with high HbF levels. Methods: In our study, qRT-PCR method was used for TAL1 expression profile by obtaining cDNA following RNA isolation in 30 beta-thalassemia major and 30 normal control individuals. GAPDH, a housekeeping gene, was used as a reference in the study. Following normalization, expression levels of TAL1 and GAPDH and normal controls were compared. HbF height and TAL1 expression levels were compared and all results were calculated as percentages. Results: The mean hemoglobin value of 30 patients with high HbF beta thalassemia major included in our study was 8.63, while the mean HbF value was 10.23%. It was found that the most common allele was the IVS.I.110 (G> A) allele with 55% frequency. While an increase between 1.1 and 5.2 times was observed in TAL1 levels in 76.6% of 30 patients (23 patients) in the qRT-PCR results, it was found to be normal in 7 patients. While TAL1 expression less than two times was observed in 13 patients, 8 out of 10 patients with more than 2 folds were found to have the highest HbF level. Conclusion: Despite the small number of patients in our study, a positive relationship was found between high HbF rate and increased TAL1 gene expression level in 76% of our beta-thalassemia major patients with high HbF. This result shows us that TAL1 and its binding sites may be new research targets for the treatment option with HbF induction. Key words: Hemoglobinopathies, Beta-Thalassemia Major, HbF, TAL1, qRT-PCR.