APC and Familial adenomatous polyposis: People with polyposis could have a genetic basis with germline mutations in polyposis-related genes, such as the APC gene, resulting in familial adenomatous polyposis (FAP), MUTYH-associated polyposis (MAP), or, rarely, in other genes such as AXIN2, GREM1, NTHL1, POLE, POLD1, or MSH3 [6,7,8,9,10].