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Induction of fetal hemoglobin synthesis by CRISPR/Cas9-mediated editing of the human β-globin locus

Chiara Antoniani, Vasco Meneghini, Annalisa Lattanzi, Tristan Felix, Oriana Romano, Elisa Magrin, Leslie Weber, Giulia Pavani, Sara El Hoss, Ryo Kurita, Yukio Nakamura, Thomas J. Cradick, Ante S. Lundberg, Matthew Porteus, Mario Amendola, Wassim El Nemer, Marina Cavazzana, Fulvio Mavilio and Annarita Miccio

Key points

  • CRISPR/Cas9-mediated disruption of the β-globin locus architecture re-activates fetal γ-globin expression in adult erythroblasts.

  • Fetal γ-globin re-activation and sickle β-globin down-regulation leads to the amelioration of the sickle cell disease cell phenotype.

Abstract

Naturally occurring, large deletions in the β-globin locus result in hereditary persistence of fetal hemoglobin, a condition that mitigates the clinical severity of sickle-cell disease (SCD) and β-thalassemia. We designed a CRISPR/Cas9 strategy to disrupt a 13.6-kb genomic region encompassing the δ- and β-globin genes and a putative γ-δ intergenic fetal hemoglobin (HbF) silencer. Disruption of just the putative HbF silencer results in a mild increase in γ-globin expression, whereas deletion or inversion of a 13.6-kb region causes a robust re-activation of HbF synthesis in adult erythroblasts, associated with epigenetic modifications and changes in the chromatin contacts within the β-globin locus. In primary, SCD patient-derived hematopoietic stem/progenitor cells, targeting the 13.6-kb region results in high proportion of γ-globin expression in erythroblasts, increased HbF synthesis, and amelioration of the sickling cell phenotype. Overall, this study provides clues for a potential genome editing approach to the therapy of β-hemoglobinopathies.

  • Submitted October 23, 2017.
  • Accepted February 22, 2018.