Distinct MLL gene rearrangements associated with successive acute monocytic and lymphoblastic leukemias in the same patient.

A patient with acute monocytic leukemia (AMoL) and t(6;11)(q27;q23) developed acute lymphoblastic leukemia (ALL) and t(4;11)(q21;23), 10 months after complete remission of the AMoL. The MLL gene, normally located at band 11q23, appeared differently rearranged in the cells of these two leukemias, showing a different origin for the two malignant clones. The responsibility of etoposide, used in treatment of the AML, in the occurrence of the ALL is probable in this patient.