RUNX1 and systemic mastocytosis: In patients with advanced SM, mostly in aggressive SM (ASM), SM with an associated hematologic neoplasm (SM‐AHN), or MC leukemia (MCL), additional genetic changes have been identified: mutations in TET2, SRSF2, ASXL1, or RUNX1, which might play a crucial role in the development of the variety of clinical outcomes and the aggressiveness of SM, and may represent new therapeutic targets.3