Multiple anatomically distinct specimens were studied in five patients (pts) with MAX-mutant GISTs and all had identical mutations, as shown by comparisons of primary GIST and subsequent metastases in two pts, and by comparisons of multiple metastases (two–ten metastases analysed per pt) in three pts (Supplementary Data 2 and Supplementary Fig. 3). Here, MAX is linked to gastrointestinal stromal tumor.