U2AF1 and myeloproliferative disorder: Approximately one third of patients with Philadelphia-negative MPN have additional mutations that alter DNA methylation (DNMT3A, TET2, and IDH1/2), chromatin modifications (ASXL1, EZH2, and IDH1/2), messenger RNA splicing (U2AF1, SF3B1, SRSF2, and ZRSR2), and DNA repair (TP53) [5].