Analysis of Methylation Status in Promoter Region of Γ- Globin Gene in Carrier and Affected Β-Thalassemia Patients with High Level of Fetal Hemoglobin in Comparison with Normal Individuals

Among the factors that may be associated with the re-expression gamma-globin in adults is the methylation pattern of the promoter region. The study aimed to determine the association between promoter methylation pattern of the gamma-globin gene in the carriers and affected beta-thalassemia individuals and its expression levels.

This study has been done as a case control- study. After taking blood samples from 30 patients and beta-thalassemia carriers and affected patients with fetal hemoglobin elevated as well as 30 normal individuals, genomic DNA was extracted. Six CpG sites of the promoter region and exon1 of the gamma-globin gene were analyzed by the bisulfite sequencing analysis method. Statistical analysis was carried out using a t-test. The values of p ≤ 0.05 were considered significant for comparing two studied groups. Data were analyzed using SPSS version 16 software.

In this study, hypomethylation of the gamma-globin promoter region in the patients and carriers compared to showed a significant differences in three CpG sites +6, -53 and -162, respectively (p<0.05). In addition, in three cases, CpG site in position -162 was semi methylated; this situation was markedly different from other samples of the patients and normal cases.

Hypomethylation of the gamma-globin gene promoter probably has an auxiliary role in fetal hemoglobin increase.