When attempting to model human leukaemia in mice by introducing pre-B-ALL-associated transgenes (such as ETV6:RUNX1, E2a:HLF or MLL:AF4) into murine hematopoietic cells, the resultant leukaemic phenotype can vary and often may emerge as T or myeloid leukaemia52. The gene discussed is KMT2A; the disease is leukemia.