title: MLL rearrangements in pediatric acute lymphoblastic and myeloblastic leukemias: MLL specific and lineage specific signatures.
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(R) 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.
  
  
  CONCLUSIONS
  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.
authors: Laboratory of HematoOncology, Department of Pediatrics "Salus Pueri", University of Padova, Padova, Italy. andrea.zangrando@unipd.it
authors: Andrea
authors: A
authors: Zangrando
authors: Marta Campo
authors: MC
authors: Dell'orto
authors: Geertruy
authors: G
authors: Te Kronnie
authors: Giuseppe
authors: G
authors: Basso