In general, patients with t(12;21) TEL-AML1 fusion and t(1;19) E2A-PBX1 fusion in ALL as well as t(8;21) AML1-ETO fusion, t(15;17) PML-RARA fusion, and inv(16) CBFB-MYH11 fusion in AML have the most favorable outcome [18–20], whereas those with the t(9;22) BCR-ABL fusion and t(4;11) MLL-AF4 fusion in ALL have dismal prognosis [21, 22]. The gene discussed is KMT2A; the disease is acute lymphoblastic leukemia.