Rapid Full Engraftment and Successful Immune Reconstitution After Allogeneic Hematopoietic Stem Cell Transplantation With Reduced Intensity Conditioning in Omenn Syndrome

The study described a successful case of allogeneic hematopoietic stem cell transplantation (HSCT) with reduced intensity conditioning (RIC) in a five-month-old boy with Omenn syndrome (OS). The patient, who had recurrent infections and cytomegalovirus (CMV) infection, received HSCT from a matched sibling donor and was treated with fludarabine, melphalan, antiviral, and immunosuppressive therapies. Post-transplant, the patient achieved rapid full engraftment and immune reconstitution without chronic graft-vs.-host disease (GvHD) and showed significant clinical improvement. Fourteen months after transplantation, the child remained in good health, indicating that RIC HSCT could be a viable treatment for OS patients with severe infections and organ damage.