KMT2A and Splenomegaly: Of note, the AML phenotype appeared more extreme in terminally ill Mcl-1tg/MLL-AF9 and BCL-2tg/MLL-AF9 mice than in WT/MLL-AF9 mice; leukocytosis and splenomegaly were more severe (Fig. 1e, f) and anaemia and thrombocytopenia more pronounced (Fig. 1g, h).