FAP and Non-polyposis Turcot syndrome: In addition to classic and attenuated FAP, other APC-associated polyposis conditions are also known, such as gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS), Turcot syndrome (associates FAP with central nervous system tumors), and Gardner syndrome (GS, association of FAP with osteomas and soft tissue tumors).