Among them are mutations affecting Polycomb-group (PcG) epigenetic regulators, enhancer of zeste homolog 2 (EZH2) and Additional sex combs like 1 (ASXL1), frequently found in hematological malignancies of myeloid or lymphoid lineage, and their concurrent mutations associates with particularly poor prognosis. The gene discussed is ASXL1; the disease is hematologic disorder.