Gene Therapy Sickle cell disease (SCD) is an autosomal-recessive disease resulting from a point mutation in the β-globin gene that leads to sickle-shaped red blood cells, pain crises, and decreased life span. Lattanzi et al. studied ex vivo β-globin gene correction in autologous patient-derived hematopoietic stem and progenitor cells (HSPCs) as a potential cure for SCD. The authors demonstrated 20% gene correction after transplantation of corrected HSPCs into immunodeficient mice, with no evidence of genotoxicity or tumorigenicity. The gene-corrected HSPCs could also be reliably produced at scale. These studies lay the groundwork for a clinical trial of this gene correction strategy in patients with SCD. Sci. Transl. Med. 13 , eabf2444 (2021).