RUNX1 and Thrombocytosis: Risk factors for leukemic transformation in PV include SRSF2, IDH2, or RUNX1 mutation, older age, leukocytosis, and abnormal karyotype [11–13], and in ET TP53, SRSF2, EZH2, U2AF1, or RUNX1 mutation, del(20q) karyotype, prefibrotic morphology, thrombosis, extreme thrombocytosis, and anemia [11, 13–16].