Acute myeloid leukemia with trisomy 11: A molecular cytogenetic study

Trisomy 11 is uncommon in acute myeloid leukemia (AML) and molecular studies have shown partial tandem duplication of the MLL gene in some cases. In a case of AML with trisomy 11, the MLL gene was found to be tandemly duplicated, leading to the formation of a fusion transcript involving splicing of exon 8 to exon 2. Fluorescence in situ hybridization revealed two populations of blasts, with about two-thirds of them showing trisomy II. These findings suggested that the trisomic and non-trisomic clones had evolved from a clone with a common submicroscopic mutation. As recent studies showed that MLL gene duplication in fact occurs more often as a primary mutation in the absence of trisomy 11, it is possible that in our case the MLL gene duplication might be the common underlying mutation. The clinical course of this case was similar to the poor prognosis reported for trisomy 11. (C) Elsevier Science, Inc., 1997.