PDGFRA and gastrointestinal stromal tumor: Gastrointestinal stromal tumours (GISTs) are mesenchymal tumours of the gastrointestinal tract with an incidence of 15–20 per million of the population.1 2 Most GISTs occurring in adults are driven by activating somatic mutations in the receptor tyrosine kinase genes KIT3 or PDGFRA4 and mutations in these proto-oncogenes predict an excellent response to tyrosine kinase inhibitors.5 Wild-type GIST (wtGIST) refers to those which are negative for activating mutations in KIT and PDGFRA.