U2AF1 and leukemia: Tefferi et al. showed that the most frequent genes in patients with MF were ASXL1, TET2, SRSF2, U2AF1, ASXL1, SRSF2, CBL, KIT, RUNX1, CEBPA, and SH2B3, which have been associated with poorer overall survival and leukemia-free survival.