PMM2 and inflammatory bowel disease: The extension of HIPKD’s spectrum of disease to include the GI tract is consistent with this hypothesis since HNF4A expression seems to reflect all the organ pathology seen in PMM2-related disease, i.e. kidney (polycystic kidney disease), pancreatic (hyperinsulinaemic hypoglycaemia), liver (hepatic cysts), gastric (foveolar hyperplasia), and intestinal tissue (inflammatory bowel disease) (Fig. 2b) (Uhlen et al. 2015).