WHO 2022 has eliminated the requirement of a ≥20% blast count as a diagnostic cut-off should a defining genetic abnormality such as PML/RARA in acute promyelocytic leukemia (APL) and core-binding factor AML (e.g., RUNX1-RUNX1T1, CBFB-MYH11) be present. The gene discussed is RUNX1; the disease is acute myeloid leukemia.