PBX1 and acute lymphoblastic leukemia: The specificity towards the NH/HeH gene expression cluster was further validated in an independent validation cohort of 140 BCP-ALL RNA ID patient samples, analysed by RNAseq [18], including 15 molecular subtypes including recurrent cytogenetic rearrangements identified by conventional diagnostics (BCR-ABL1, KMT2A-AFF1, ETV6-RUNX1, TCF3-PBX1) (Additional file 8).