KMT2A and acute lymphoblastic leukemia: ALL subgroups with distinct biological characteristics are frequently characterized by dysregulated transcription factors or kinases—most prominently the fusion proteins TEL-AML1 (Translocation Ets Leukemia-Acute Myeloid Leukemia 1 protein) encoded by t(12;21)(p13;q22) in presumed good risk ALL, or Bcr-Abl (Breakpoint cluster region-Abelson murine leukemia virus) encoded by t(9;22)(q34;q11) and MLL-AF4 (Mixed Lineage Leukemia-ALL1 Fused gene on chromosome 4) by t(4;11)(q21;q23) in high risk ALL.