While both ALL and AML are defined by genetic drivers, the 2022 World Health Organization (WHO)2 and International Consensus Classification3 guidelines continue to define MPAL by immunophenotype with only a subset with associated genetic abnormalities (BCR::ABL1 fusion, KMT2A, ZNF384, and BCL11B rearrangements). Here, BCL11B is linked to acute lymphoblastic leukemia.