MECOM and acute lymphoblastic leukemia: While EVI1 is most frequently associated with myeloid malignancies, it is also dysregulated in some cases of adult and pediatric acute lymphoblastic leukemia (ALL) and chronic lymphocytic leukemia, most commonly in B-ALL.41 As in AML, CML, and MDS, high EVI1 expression in pediatric ALL may serve as a predictive factor for adverse clinical outcome.