Study Evaluating a Gene Therapy for IPEX Syndrome Through the Expression of FOXP3 on Deficient T Cells to Produce Tregs-like.

Inclusion Criteria: * Male patients only * Patients aged from 1 - 45 years of age (the first three patients will be aged between 10 - 45 years of age) * Patient with IPEX syndrome caused by mutation of the FOXP3 gene * Patients are eligible from the second line of treatment onward, even those under controlled disease * Patient with recurrent IPEX symptoms, under immune suppressive medications * Patient for whom HSCT is not feasible or when no suitable compatible donor is available * Patients who have had prior allogeneic blood stem cell transplantation (HSCT) with engraftment failure defined as no intake of donor cells * Patient or parental, guardian's patient signed informed consent * Male participants of reproductive potential with a partner of childbearing potential (WOCBP): willing to use an effective method of contraception during the trial and for at least 12 months post-infusion * Affiliation to a French or European social security scheme Exclusion Criteria: * Unwillingness to return for follow-up during the 2-year study and during the 15 years of long term follow up study. * Patient with short life expectancy * Patient on AME (state medical aid) (unless exemption from affiliation). * Diagnosis of a significant psychiatric disorder of the patient that could seriously impede the ability to participate in the study. * Eligible for an HLA matched sibling or matched unrelated donor blood stem cell transplant (HLA 10/10) and be willing to undergo transplant. * Patients w…