[Methylation status of γ-globin gene promoter in β-thalassemia major]

This study was aimed to detect and identify the promoter CpG island methylation of γ-globin gene in peripheral blood mononuclear cells from patients with β-thalassemia major and healthy adult in Guangxi province, as well as to analyze the difference of promoter methylation rate of each CpG sites between them, and then to screen the promoter CpG island main methylation sites which maybe influence γ-globin expression. The template DNA was modified by bisulfite genomic sequencing PCR; the promoter sequences of γ-globin gene were amplified by technique Touchdown PCR, and then the PCR products were cloned and sequenced for obtaining methylation status of each CpG sites in target fragments, and then the accurate methylation sites and levels were detected quantitatively. The results indicated that the 4 CpG methylation sites locating at 28, 122, 231 and 234 bp in sequences were hypermethylated. As compared with healthy adults, the DNA methylation rate of 122 and 231 bp CpG sites in patients with β-thalassemia major was obviously lower, however, methylation rates of 28 and 234 bp sites were not significantly different between patients and healthy adults. It is concluded that the methylation sites 28, 122, 231 and 234 bp of γ-globin gene promoter are found both in patients with β-thalassemia major and healthy adults. The 122 and 231 bp sites are identified preliminarily to be involved in the regulation of γ-globin expression. This study provides the experimental evidence for alleviating the clinical symptoms of β-thalassemia major and targeting gene treatment through the regulation of γ-globin.