A large multi-center series of over 80 patients with LIG4-deficiency, Nijmegen Breakage Syndrome and Cernunnos-XLF deficiency, transplanted for numerous indications including immunodeficiency, severe autoimmunity, bone marrow failure and malignancy, demonstrated that patients receiving a reduced intensity, or Fanconi-based regimen had significantly better survival in the immediate post transplant period than those receiving a fully myelo-ablative conditioning regimen (45). This evidence concerns the gene LIG4 and Immunodeficiency.