PDGFRA and gastrointestinal stromal tumor: Indeed, the frequency of complex or large alterations and of low-allele-fraction mutations is high (18 cases carrying at least one of the two; 13.2% of all KIT/PDGFRA-mutant patients), thus further highlighting the need for centralization of GIST molecular diagnosis at least for WT cases, since these alterations would have probably been missed by routine molecular analyses.