KMT2A and acute lymphoblastic leukemia: B-lymphoblastic leukemia/lymphoma (B-ALL) is the most common type of acute lymphoblastic leukemia, and comprises genetically distinct subtypes including B-ALL with Philadelphia chromosome t(9;22)(q34;q11.2) (BCR-ABL1), t(v;11q23) (MLL rearranged), t(12;21)(p13;q22) (TEL-AML1), t(5;14)(q31;q32) (IL3-IGH), t(1;19)(q23;p13.3) (E2A-PBX1), hyperdiploidy, hypodiploidy, and about 25% cases without defined cytogenetic abnormalities [15].