| Summary: | <p>Abstract</p> <p>Background</p> <p>The presence of <it>MLL </it>rearrangements in acute leukemia results in a complex number of biological modifications that still remain largely unexplained. Armstrong et al. proposed <it>MLL </it>rearrangement positive ALL as a distinct subgroup, separated from acute lymphoblastic (ALL) and myeloblastic leukemia (AML), with a specific gene expression profile. Here we show that MLL, from both ALL and AML origin, share a signature identified by a small set of genes suggesting a common genetic disregulation that could be at the basis of mixed lineage leukemia in both phenotypes.</p> <p>Methods</p> <p>Using Affymetrix<sup>® </sup>HG-U133 Plus 2.0 platform, gene expression data from 140 (training set) + 78 (test set) ALL and AML patients with (24+13) and without (116+65) <it>MLL </it>rearrangements have been investigated performing class comparison (SAM) and class prediction (PAM) analyses.</p> <p>Results</p> <p>We identified a <it>MLL </it>translocation-specific (379 probes) signature and a phenotype-specific (622 probes) signature which have been tested using unsupervised methods. A final subset of 14 genes grants the characterization of acute leukemia patients with and without <it>MLL </it>rearrangements.</p> <p>Conclusion</p> <p>Our study demonstrated that a small subset of genes identifies <it>MLL</it>-specific rearrangements and clearly separates acute leukemia samples according to lineage origin. The subset included well-known genes and newly discovered markers that identified ALL and AML subgroups, with and without <it>MLL </it>rearrangements.</p>
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