PDGFRA and gastrointestinal stromal tumor: Platelet Derived Growth Factor Receptor Alpha (PDGFRA) mutations occur in only about 5–7% of gastrointestinal stromal tumors (GIST), and mainly involve the A-loop encoded by exon 18 (~5%), or more rarely the JM domain encoded by exon 12 (~1%), or the ATP binding domain encoded by exon 14 (<1%) (1, 2).