Creating New Cis-Regulatory Elements of HBD to Reactivate Delta-Globin.

β-thalassemia and sickle cell disease (SCD) are global monogenic blood system disorders, and reactivated δ-globin is expected to replace missing or abnormal β-globin. With the development of gene editing technology, activating γ-globin for treating β-thalassemia and SCD has been highly successful. However, δ-globin, as another important potential therapeutic target, has few related studies. Gene editing technology introduced cis-acting elements, including NF-Y, KLF1, GATA1, and TAL1, into the regulatory region of HBD, successfully activating the expression of δ-globin. It was confirmed that the activation effect of δ-globin was closely related to the location of the introduced cis-acting elements. In this study, the mutation creates a de novo binding site for KLF1 at -85∼93 bp upstream of the transcription start site of the HBD gene, as well as the site for TAL1 and GATA1 cobinding motifs at -59 to ∼-78 bp, which could effectively activate δ-globin.