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Open Access Research article

MLL rearrangements in pediatric acute lymphoblastic and myeloblastic leukemias: MLL specific and lineage specific signatures

Andrea Zangrando*, Marta Campo Dell'Orto, Geertruy te Kronnie and Giuseppe Basso

Author Affiliations

Laboratory of HematoOncology, Department of Pediatrics "Salus Pueri", University of Padova, Padova, Italy

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BMC Medical Genomics 2009, 2:36  doi:10.1186/1755-8794-2-36

Published: 23 June 2009

Abstract

Background

The presence of MLL rearrangements in acute leukemia results in a complex number of biological modifications that still remain largely unexplained. Armstrong et al. proposed MLL 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.

Methods

Using Affymetrix® 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) MLL rearrangements have been investigated performing class comparison (SAM) and class prediction (PAM) analyses.

Results

We identified a MLL 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 MLL rearrangements.

Conclusion

Our study demonstrated that a small subset of genes identifies MLL-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 MLL rearrangements.