Among gastrointestinal tract neoplasms, such GNAS gene alterations have been found in pancreatic intraductal papillary mucinous neoplasms (mostly of intestinal type) and colloid carcinomas [31,32,33], low-grade appendiceal mucinous neoplasms/pseudomyxoma peritonei [30], intestinal villous adenomas [34], in addition to gastric and duodenal pyloric gland adenomas and duodenal adenocarcinoma [16,21,27,35]. Here, GNAS is linked to duodenal adenocarcinoma.