Histologically, there are two main types, spindle-cell GIST, mainly found in mutated KIT or BRAF GIST (in 70% of cases), and epithelioid-cell GIST (20%), mainly found in platelet-derived growth factor receptor A (PDGFRA) or succinate dehydrogenase (SDH) GIST. The gene discussed is PDGFRA; the disease is gastrointestinal stromal tumor.