Their abnormal expression is frequently observed in lymphoid, myeloid and mixed-lineage leukaemias (MLL), and is characteristic of translocations involving the MLL gene.12 High-level expression of HOXA genes can also be seen in leukaemia patients without MLL translocations13, 14 and confers poor prognosis in both T-ALL and acute myeloid leukaemia (AML)12, 15 thus emphasizing the need for further research to identify key downstream mediators of the leukaemic phenotype. Here, KMT2A is linked to acute lymphoblastic leukemia.