MAX genomic mutations were more common in non-gastric than gastric GISTs (P=0.001 for the 71 pts with known GIST primary sites, two-tailed Fisher's exact test) and this association remained significant when GISTs with NF1 mutations—which are generally of small bowel origin—were removed from consideration (P=0.004 for 61 pts with NF1-wild type GISTs of known primary sites). The gene discussed is NF1; the disease is gastrointestinal stromal tumor.