An FGFR1 mutant (FGFR1 N546K), which occurs in the tyrosine kinase domain of FGFR1 as a result of an activating mutation, has been identified in pineal tumor, peritoneal sarcoma, pilocytic astrocytoma, gastrointestinal stromal tumors (GISTs), pheochromocytomas, liposarcoma, breast sarcoma, malignant peripheral nerve sheath tumor, neuroblastoma, paraganglioma, and glioblastoma (Lew et al., 2009; Jones et al., 2013; Helsten et al., 2016; Toledo et al., 2016; Nannini et al., 2017). The gene discussed is FGFR1; the disease is gastrointestinal stromal tumor.