Editing a γ-globin repressor binding site restores fetal hemoglobin synthesis and corrects the sickle cell disease phenotype

Sci Adv. 2020 Feb 12;6(7):eaay9392. doi: 10.1126/sciadv.aay9392. Print 2020 Feb.

Abstract

Sickle cell disease (SCD) is caused by a single amino acid change in the adult hemoglobin (Hb) β chain that causes Hb polymerization and red blood cell (RBC) sickling. The co-inheritance of mutations causing fetal γ-globin production in adult life hereditary persistence of fetal Hb (HPFH) reduces the clinical severity of SCD. HPFH mutations in the HBG γ-globin promoters disrupt binding sites for the repressors BCL11A and LRF. We used CRISPR-Cas9 to mimic HPFH mutations in the HBG promoters by generating insertions and deletions, leading to disruption of known and putative repressor binding sites. Editing of the LRF-binding site in patient-derived hematopoietic stem/progenitor cells (HSPCs) resulted in γ-globin derepression and correction of the sickling phenotype. Xenotransplantation of HSPCs treated with gRNAs targeting the LRF-binding site showed a high editing efficiency in repopulating HSPCs. This study identifies the LRF-binding site as a potent target for genome-editing treatment of SCD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anemia, Sickle Cell* / genetics
  • Anemia, Sickle Cell* / therapy
  • Binding Sites
  • CRISPR-Cas Systems
  • Fetal Hemoglobin / genetics
  • Fetal Hemoglobin / metabolism
  • Gene Editing / methods
  • Humans
  • Phenotype
  • beta-Globins / genetics
  • beta-Globins / metabolism
  • beta-Thalassemia* / genetics
  • beta-Thalassemia* / metabolism
  • beta-Thalassemia* / therapy
  • gamma-Globins / genetics
  • gamma-Globins / metabolism

Substances

  • beta-Globins
  • gamma-Globins
  • Fetal Hemoglobin