RUNX1 is among the most over-expressed genes in childhood ALL [18] and is highly amplified in a poor prognostic B-ALL subgroup [19] while presumptive loss-of-function RUNX1 mutations have been observed in a small proportion of T-ALLs where network analysis further implicated RUNX1 as a candidate tumor suppressor [20]. This evidence concerns the gene RUNX1 and acute lymphoblastic leukemia.