Given the dreaded fatal complications of hematologic neoplasia, bone marrow failure and chronic liver disease, the best chance LIG4-deficient patients with severe (hematological/immunological) phenotypes have of reaching adulthood, might be to receive an HSCT (11, 30) under the best possible conditions (HLA-identical donor, a reduced intensity conditioning regime with low-dose Cyclosporin A (24, 30, 31), infection-free, no organ failure). This evidence concerns the gene LIG4 and Bone marrow hypocellularity.