Reactivation of fetal hemoglobin (HbF, α2γ2) holds a therapeutic target for β-thalassemia and sickle cell disease. Although many HbF regulators have been identified, the methylation patterns in β-globin cluster driving the fetal-to-adult hemoglobin switch remains to be determined. Here, we evaluated DNA methylation patterns of the β-globin cluster from peripheral bloods of 105 β0/β0 thalassemia patients and 44 normal controls. We also recruited 15 bone marrows and 4 cord blood samples for further evaluation. We identified that the CpG sites in the locus control region (LCR) DNase I hypersensitive site 4 and 3 (HS4-3) regions, and γ- and β-globin promoters displayed hypomethylation in β0/β0-thalassemia patients, especially for the patients with high HbF level, as compared with normal controls. Furthermore, hypomethylations in most of CpG sites of the HS4-3 core regions were also observed in bone marrows (BM) of β0/β0-patients compared with normal controls; and methylation level of γ-globin promoter -50 and + 17 CpG sites showed lower methylation level in patients with high HbF level compared with those with low HbF level and a negative correlation with HbF level among β0-thalassemia patients. Finally, γ-globin promoter + 17 and + 50 CpG sites also displayed significant hypomethylation in cord blood (CB) tissues compared with BM tissues from normal controls. Our findings revealed methylation patterns in β-globin cluster associated with β0 thalassemia disease and γ-globin expression, contributed to understand the epigenetic modification in β0 thalassemia patients and provided candidate targets for the therapies of β-hemoglobinopathies.

中文翻译：

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β-地中海贫血患者β-珠蛋白簇的DNA甲基化模式

胎儿血红蛋白（HbF，α2γ2）的重新激活是 β-地中海贫血和镰状细胞病的治疗靶点。尽管已经确定了许多 HbF 调节剂，但驱动胎儿到成人血红蛋白转换的 β-珠蛋白簇中的甲基化模式仍有待确定。在这里，我们评估了 105 名 β0/β0 地中海贫血患者和 44 名正常对照的外周血中 β-珠蛋白簇的 DNA 甲基化模式。我们还招募了 15 个骨髓和 4 个脐带血样本进行进一步评估。我们发现基因座控制区 (LCR) DNase I 超敏位点 4 和 3 (HS4-3) 区域中的 CpG 位点以及 γ- 和 β- 珠蛋白启动子在 β0/β0-地中海贫血患者中表现出低甲基化，尤其是对于患者与正常对照相比，具有高 HbF 水平。此外，与正常对照相比，在 β0/β0 患者的骨髓 (BM) 中也观察到 HS4-3 核心区域的大多数 CpG 位点的低甲基化；γ-珠蛋白启动子-50和+17个CpG位点甲基化水平与β0-地贫患者相比，HbF水平高的患者甲基化水平低于HbF水平低的患者，与HbF水平呈负相关。最后，与正常对照的 BM 组织相比，γ-珠蛋白启动子 + 17 和 + 50 CpG 位点在脐带血 (CB) 组织中也显示出显着的低甲基化。我们的研究结果揭示了与 β0 地贫疾病和 γ-珠蛋白表达相关的 β-珠蛋白簇中的甲基化模式，有助于了解 β0 地贫患者的表观遗传修饰，并为 β-血红蛋白病的治疗提供候选靶点。