The limited overlap of gene expression profiles associated with high EVI1 expression in different forms of childhood leukaemia and the different levels of expression of some co-regulated genes implies the possibility of tissue specificity, and the impact of cell of origin for EVI1-mediated transcriptional regulation, which has also been suggested for MLL-rearranged AML subtypes.16 High EVI1 expression itself is likely to be a secondary event in paediatric lymphoblastic and myeloid leukaemia. This evidence concerns the gene MECOM and myeloid leukemia.