As with other myeloid neoplasms, additional mutations in genes encoding for epigenetic regulators (ASXL1, EZH2, IDH2, TET2), splicing factors (SRSF2, SF3B1, U2AF1), signaling molecules (CBL, JAK2, N/KRAS), or transcription factors (RUNX1) have been reported in SM with significantly higher mutation frequencies in AdvSM versus more indolent forms [12]. Here, RUNX1 is linked to systemic mastocytosis.