Abstract
Sickle Cell Disease (SCD), one of the world’s most common genetic disorders, causes anemia and progressive multiorgan damage that typically shortens lifespan by decades; currently there is no broadly applicable curative therapy. Here we show that Cas9 RNP-mediated gene editing with an ssDNA oligonucleotide donor yields more than 20% correction of the sickle mutation in long-term engrafting human HSCs. Using RNA-seq, we further find that in vivo erythroid differentiation markedly enriches for cells carrying corrected ß-globin alleles. Adoption of a high-fidelity Cas9 variant demonstrates that this approach can yield efficient editing with almost no off-target events. These findings indicate that the sickle mutation can be corrected in human HSCs at levels that are likely to be curative if translated into a therapy.