Analysis of outlier gene expression in high-risk childhood ALL previously identified eight ALL subgroups, several of which harboured recurring genetic alterations including rearrangement of KMT2A (MLL) (ROSE group 1, R1), TCF3-PBX1 (R2), deregulation of ERG (R6) and Ph+/Ph-like ALL (R8), and so on8. This evidence concerns the gene PBX1 and acute lymphoblastic leukemia.