In more than 75% of acute myeloid leukemia (AML) cases and >90% of acute lymphoblastic leukemia (ALL) cases involving MLL translocations, the MLL-fusion partner is one of seven members of the transcriptional elongation complex, most commonly, AF9 and AF4, respectively (Marschalek, 2011). The gene discussed is KMT2A; the disease is acute myeloid leukemia.