Chromosomal translocations involving MLL gene represent frequent cytogenetic abnormalities found in hematologic malignancies, occurring in 5–6% of patients with acute myeloid leukemia (AML), 7–10% of acute lymphoblastic leukemia (ALL), 60–70% of all acute leukemias in infants, and in most patients with t-AML/t-ALL secondary to therapy that is targeting topoisomerase II [3]. This evidence concerns the gene KMT2A and acute myeloid leukemia.