Acquired genetic alterations in RUNX1 are frequently associated with numerous myeloid malignancies, especially acute myeloid leukaemia (AML) (40% of FAB M0 immature AMLs 1) and more rarely with T cell acute lymphoblastic leukaemia (T‐ALL) (25% of early thymic immature T‐ALL (ETP‐ALL) 2). The gene discussed is RUNX1; the disease is acute myeloid leukemia.