Gene Therapy for X Linked Severe Combined Immunodeficiency

Inclusion Criteria: 1. X-SCID patients diagnosed by IL2RG single gene mutation 2. No HLA（human leukocyte antigen） matching donor 3. Hematopoietic stem cell transplantation failed and the time from transplantation was more than 18 months 4. Severe and persistent refractory infections 5. Life expectancy of \> : 4 months 6. HIV PCR in peripheral blood was negative 7. the children and their families signed informed consent and were willing to enter the clinical trial and complete follow-up Exclusion Criteria: 1. The patient has diagnosed with hematological malignant diseases 2. Received chemotherapy within 3 months 3. HIV infection or HBV（hepatitis B virus） infection 4. The patient or his first-degree relative has developed a malignant tumor within the age of 18 or has been diagnosed with malignant tumor prone genes 5. Although the patient with X-SCID was diagnosed as IL2RG single gene mutation , the clinical phenotype was not severe, so they could continue to wait for the donor search; 6. Patients whose family members have no intention to continue the follow-up treatment in any link