The GNAS mutation was significantly associated with the morphological type of IPMN (P < 0.001), and it was more common in the intestinal type (27/29, 93%) than in the gastric (6/11, 55%) and pancreatobiliary (7/16, 44%) types, but no mutations of GNAS were observed in any oncocytic (0/5, 0%) type. This evidence concerns the gene GNAS and pancreatic intraductal papillary-mucinous neoplasm.