KIT and gastrointestinal stromal tumor: Platelet-Derived Growth Factor Receptor Alpha (PDGFRA) mutations are, by far, the most infrequent mutations of the two known driving kinase genes (KIT - Proto-Oncogene Receptor Tyrosine Kinase and PDGFRA) in gastrointestinal stromal tumours (GIST), and they occur in approximately 5–7% of cases1,2.