CRISPR/Cas9-based therapies are currently being tested for the amelioration of blood disorders in a rapidly growing number of clinical trials (Table 1) (Kanter et al., 2021), and a few are close to garnering U.S. Food and Drug Administration (FDA) approval, including exa-cel, which uses CRISPR/Cas9 to disrupt the erythroid-specific B-cell lymphoma/leukemia 11A (BCL11A; Box 1) enhancer and thus reactivate the production of fetal hemoglobin in autologous CD34+ HSPCs. The gene discussed is BCL11A; the disease is hematologic disorder.