Therapy related leukemias, associated with topoisomerase II inhibitors, often present rearrangements involving the MLL gene on chromosome band 11q23, or to a lesser extent, t(8;21), t(3;21); t(8;16), t(15;17), t(9;22) or inv(16), to then emerge as overt leukemias in a period of 2 to 3 years following therapy completion (Felix, 1998). This evidence concerns the gene KMT2A and leukemia.