Haploidentical Hematopoietic Stem Cell Transplantation Patients With Wiskott-Aldrich Syndrome

Wiskott - Aldrich syndrome (WAS) is a rare disorder curable only through allogeneic hematopoietic stem cell transplantation. A mismatched family member is an option when no human leukocyte antigen (HLA-immune system type) matched related or matched unrelated donor is available. This study will evaluate a novel therapeutic strategy for patients with WAS who undergo haploidentical transplantation using a parental donor. To reduce the risk of transplant-related toxicities, participants will receive a reduced intensity chemotherapy and antibody regimen (conditioning treatment). Participants will then receive an infusion of donor stem cells depleted of certain white blood cells called T- and B-lymphocytes. The stem cell depletion processing will be done through the use of the investigational CliniMACS device. A certain number of T-lymphocytes will be added back to the processed stem cell graft prior to infusion into the recipient. The primary objective of this study is to determine the safety of haploidentical transplantation in WAS patients using this specified conditioning regimen and engineered graft. Safety will be defined in terms of engraftment (meaning how well the graft grows and functions after infusion) and regimen-related toxicity within the first 100 days after transplant.