Inclusion Criteria: * Age: up to 65 years * Diagnosis of WAS defined by genetic mutation and at least one of the following criteria: * Severe Wiskott-Aldrich Syndrome (WAS) gene mutation, defined by literature data (genotype/phenotype studies).; * Absent WASP expression, assessed by flow cytometry; * Severe clinical score (Zhu clinical score ≥ 3); * No human leukocyte antigen (HLA)-identical related donor available for hematopoietic stem cells transplant (HSCT). Exclusion Criteria: * End-organ dysfunction, severe active infection not responsive to treatment or other severe disease or clinical condition which, in the judgment of the investigator, would make the patient inappropriate for entry into this study. * Malignant neoplasia (except local skin cancer) or a documented history of hereditary cancer syndrome. * Myelodysplasia, cytogenetic alterations characteristic of myelodysplastic syndrome and acute myeloid leukaemia , or other serious haematological disorders * Documented human immunodeficiency virus (HIV) infection * Prior allogeneic hematopoietic stem cell transplantation, with evidence of residual cells of donor origin * Symptomatic herpes zoster, not responsive to specific treatment * Evidence of acute tuberculosis * Acute or chronic stable Hepatitis B * Presence of positive Hepatitis C RNA test result at screening * Patients not eligible for mobilization protocols in order to obtain CD34+ cells * Previous Gene Therapy