Among the components of PRC1.1, BCOR and BCLRL1, but not PCGF1 are targeted by somatic gene mutations in various hematological malignancies, including myelodysplastic syndrome (MDS), chronic myelomonocytic leukemia (CMML), and acute myeloid leukemia (AML) (Isshiki and Iwama, 2018). The gene discussed is BCOR; the disease is acute myeloid leukemia.