Amplification of the IIq23 region in acute myeloid leukemia

Cytogenetic abnormalities involving the 11q23 region are found in both acut e lymphoblastic leukemia (ALL) and myeloid leukemia (AML). Molecular conseq uences of 11q23 translocations are the formation of chimeric genes, all of them involving the MLL (mixed-lineage leukemia) gene. To evaluate the usefu lness of fluorescence in situ hybridization (FISH) in detecting MLL rearran gements in AML, we analyzed 181 patients with an MLL-specific probe. Among them, we detected three patients with multiple FISH signals, reflecting gen omic amplification of this chromosomal region. Extra copies of MLL have bee n reported previously in four patients, but did not correspond to a true ge ne amplification. For the first time, we describe genomic amplification of the 11q23 region (up to more than 50 copies) in AML patients. This genomic amplification could affect MLL, but other genes in the vicinity could also be the primary target. Genes Chromosomes Cancer 26:166-170, 1999. (C) 1999 Wiley-Liss, Inc.