Structural rearrangements involving the MLL gene at 11q23 are common recurring abnormalities in de novo and therapy-related hematologic disorders. MLL rearrangement most often results from translocation or partial tandem duplication, although recent published reports suggest a different mechanism by which MLL might participate in leukemogenesis: MLL amplification. We report two patients with myeloid disorders who showed amplification of MLL at diagnosis and who, like the majority of reported cases, had an older age at onset and on aggressive clinical course. Additionally, we summarize the salient clinical, cytogenetic and molecular findings of the 29 other cases of MLL amplification that have thus far been reported.
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