Activating mutations of the receptor tyrosine kinases KIT1 or PDGFRA2 are initiating or early events in most gastrointestinal stromal tumours (GISTs) and indeed are present in micro-GISTs, which are asymptomatic subcentimetre GIST lesions found in one-third of the general population3. This evidence concerns the gene NTRK1 and gastrointestinal stromal tumor.