In liquid tumors such as leukemia and lymphomas, it believed that, one of the most prevalent category of mutations involving cancer driver genes are chromosomal rearrangements such as BCR-ABL1 in chronic mylogenous leukemia (CML) [13], fusions involving nucleopins 98 and 124 and MLL gene fusions in acute myelogenous leukemia (AML) [2, 14, 15], and TEL-AML1 and TCF3-PBX1 in acute lymphoblastic leukemia (ALL) [16–18]. The gene discussed is KMT2A; the disease is acute lymphoblastic leukemia.