A MLL partial tandem duplication (MLLPTD), the result of a tandem duplication of an internal portion of the MLL gene that spans either exons 2 to 6 or exons 2 to 8, is present in approximately 10% of CN-AML [64, 65]. MLLPTD mutation has been identified as a poor prognostic factor for EFS [60, 66, 67] and OS [27, 41, 60, 67]. This evidence concerns the gene KMT2A and acute myeloid leukemia.