To identify 6q TSG contributing to childhood B-ALL, we integrated SNP6.0 array, in-vitro and in-vivo clone tracking assays and expression data, implicating the transcription factors FOXO3 and PRDM1. To investigate the mechanisms by which they suppress leukaemia growth, we combined analysis of gene sets dysregulated by PRDM1, FOXO3 and the related transcription factor FOXO1, with data from a CRISPR-Cas9 knock-out (KO) screen. Here, PRDM1 is linked to precursor B-cell acute lymphoblastic leukemia.