FISH analysis of an AML-M5a with segmental rearrangements involving 11q23-MLL region

A 66-year-old man was diagnosed 10 years ago with thrombocytosis and treated with hydroxyurea. Recently, his condition deteriorated and he was found to have 68% blasts in the blood and AML-M5a. Conventional cytogenetic analysis and fluorescence in situ hybridization studies using 11-painting and MLL probes showed that chromosome 11 had duplications or triplications; the markers were also derived from the chromosome 11-MLL region. Therefore, we have demonstrated segmental rearrangement of chromosome 11 involving the MLL region resulting in multiple copies of the MLL gene.