APC and gastric adenocarcinoma and proximal polyposis of the stomach: However, certain pathogenic APC variants are associated with the density of colorectal adenomas and the occurrence of extracolonic manifestations (e.g., fundic gland polyposis, duodenal adenomas, osteomas, desmoid tumors, and the CHRPE phenotype) in patients with FAP [15, 25, 26, 128].