U2AF1 and myelofibrosis: The presence of at least one of the 3 variants/mutations (ASXL1, SRSF2, and IDH2) is associated with inferior overall and myelofibrosis-free survival in patients with PV. SH2B3, IDH2, U2AF1, SF3B1, EZH2, and TP53 mutations are identified as significant risk factors for inferior overall, myelofibrosis-free survival, and leukemia-free survival in patients with ET (85).