Inclusion Criteria:  Patient less than one year SCID patients with confirmed biallelic mutations in the Artemis (DCLRE1C) gene Absence of an HLA genoidentical donor or without rapidly available HLA-compatible unrelated donor (within six weeks of diagnosis) The patient can be treated by gene therapy without delay in case of active life threatening infections compromising the short-term prognosis and for which the delay in finding a phenoidentical donor is incompatible with the patient's condition of health. Active life threatening infections are defined as: viral respiratory infection, CMV infection, adenovirus infection, disseminated BCGitis or other infections grade ≥ 4 according to CTCAE scale Parental, guardian's patient signed informed consent.  Exclusion Criteria  Unwillingness to return for follow-up during the first 2 years study and the long term follow-up HIV-1 or 2 or HTLV1 infections Hypersensitivity to nivestim or busulfan Unable to tolerate general anesthesia and/or marrow harvest or peripheral blood stem cell collection (apheresis) or insertion of central venous catheter.