HoweverKMT2A-rearranged leukemia development was not observed even inAtm-/- mice.Kmt2a-AF4 knock-in mice develop leukemia afterprolonged latency, suggesting that a second hit, which might be induced by apossibly defective DNA damage response, is required for full leukemogenesis [31]. Here, KMT2A is linked to leukemia.