In gastrointestinal stromal tumors (GIST), mutations of exons 9, 11, 13 and 17 of KIT, and of exons 12, 14 and 18 of PDGFRA are key drivers of oncogenesis and are present in around 85–90% of tumors, whereas the remaining 10–15% of these cancers is referred as KIT/PDGFRA wild-type GISTs. The gene discussed is KIT; the disease is cancer.