Upon age-adjusted multivariate analysis of their impact on overall, leukemia-free, and myelofibrosis-free survival, molecular variants associated with adverse outcomes included ASXL1, SRSF2, and IDH2 in PV, and SH2B3/LNK, SF3B1, U2AF1, TP53, IDH2, and EZH2 in ET. Here, SRSF2 is linked to essential thrombocythemia.