(A) Gene therapy requires the harvesting of HSPCs from the patient, transduction of these cells with a nonsickling viral vector, and myeloablative chemotherapy followed by autologous BMT. (B) Gene editing also requires the harvesting of HSPCs from the patient. Gene editing of HSPCs is accomplished with electroporation of gene-editing reagents, followed by myeloablative conditioning and autologous BMT using the gene-corrected cells. (C) alloBMT can be from an HLA-matched sibling donor, a matched unrelated donor, or an HLA-haploidentical family donor. Bone marrow is harvested from a healthy donor. Traditionally, patients received myeloablative chemotherapy, but in recent years nonmyeloablative therapy, especially for HLA-haploidentical BMT with post-transplantation cyclophosphamide, has become more common. Healthy donor HSPCs are infused, followed by post-transplantation administration of cyclophosphamide to prevent GVHD and graft rejection. Children with strokes and adults with severe heart, lung, or kidney disease or strokes are typically excluded from gene therapy trials but are eligible to participate in the NIH-supported HLA-haploidentical BMT with post-transplantation cyclophosphamide phase II trial (NCT03263559).