In this issue of Blood, Touzot et al report that autologous gene therapy/hematopoietic stem cell transplantation (HSCT) for infants with X-linked severe combined immune deficiency (SCID-X1) lacking a matched sibling donor may have better outcomes than haploidentical (haplo) HSCT. Because gene therapy represents an autologous transplant, it obviates immune suppression before and after transplant, eliminates risks of graft versus host disease (GVHD), and, as the authors report, led to faster immunological reconstitution after transplant than did haplo transplant.