Familial Polyposis Syndromes

Abstract

Although sporadic polyps in the gastrointestinal tract are common with increasing age, the finding of a large number of polyps raises suspicion for a hereditary polyposis syndrome associated with a germline genetic mutation. Because many of these hereditary polyposis syndromes also confer an increased risk of gastrointestinal and extraintestincal cancers, implicated in approximately 1% of all colorectal cancers, recognition of these syndromes is critical to offer preventive screening measures. A key distinguishing feature is polyp histologic type, ranging from adenomatous, to serrated, to hamartomatous. A clinical diagnosis can be confirmed by genetic testing for a germline mutation in known cancer susceptibility genes, although in many polyposis families, a genetic etiology has not yet been identified. This review covers familial adenomatous polyposis, MUTYH-associated polyposis, polyposis associated with polymerase proofreading, juvenile polyposis syndrome, PTEN hamartoma tumor syndromes, hereditary mixed polyposis syndrome, and serrated polyposis. The figures shows the spectrum of histologic types and genetic etiologies of hereditary polyposis syndromes. Tables list polyposis syndromes, American College of Gastroenterology surveillance guidelines for hereditary polyposis syndromes, diagnostic criteria for juvenile polyposis syndrome, diagnostic criteria for PTEN hamartoma tumor syndrome, and World Health Organization diagnostic criteria for serrated polyposis syndrome. This review contains 1 highly rendered figure, 5 tables, and 172 references Key words: Familial adenomatous polyposis; Polyposis syndromes; Gastrointestinal polyps; Hereditary polyposis syndromes