Six months after transplantation, Atm<sup>-/-</sup> mice showed signs of aging, but they maintained the rescue of T cells maturation, showed DNA damage response, and prevented thymoma.<h4>Conclusion</h4>We can conclude that wild-type enriched HSPCs transplantation into young Atm-deficient mice can ameliorate A-T hematopoietic phenotypes and prevent tumor of hematopoietic origin. This evidence concerns the gene ATM and neoplasm.