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

• Published in: Science advances Vol. 6; no. 7
• Main Authors: Weber, Leslie, Frati, Giacomo, Felix, Tristan, Hardouin, Giulia, Casini, Antonio, Wollenschlaeger, Clara, Meneghini, Vasco, Masson, Cecile, De Cian, Anne, Chalumeau, Anne, Mavilio, Fulvio, Amendola, Mario, Andre-Schmutz, Isabelle, Cereseto, Anna, El Nemer, Wassim, Concordet, Jean-Paul, Giovannangeli, Carine, Cavazzana, Marina, Miccio, Annarita
• Format: Journal Article
• Language: English
• Published: American Association for the Advancement of Science 12.02.2020
• Subjects: Health and Medicine; SciAdv r-articles
• ISSN: 2375-2548
• DOI: 10.1126/sciadv.aay9392

Editing the fetal γ-globin promoters in hematopoietic stem cells from sickle cell disease patients induces therapeutic γ-globin levels. 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.