Coinheritance of germline mutations in APC and MUTYH genes defines the clinical outcome of adenomatous polyposis syndromes

Familial adenomatous polyposis (FAP) and MUTYH-associated polyposis (MAP) are colon cancer predisposition syndromes. FAP is an autosomal dominant inherited condition caused by germline mutations in the adenomatous polyposis coli (APC) gene and characterized by hundreds to thousands of colorectal adenomas. FAP can be classified into several clinical forms, including profuse FAP (>1,000 adenomas), intermediate FAP (100e1,000 adenomas), attenuated FAP (AFAP) (<100 adenomas), and gastric polyposis and desmoid FAP (GD-FAP) (<50 adenomas).