Hamartomatous polyposis syndromes: genetic pathways

Hamartomatous polyposis syndromes are a group of clinically distinct but perhaps genetically related disorders in which the predominant finding is multiple hamartomatous polyps in the gastrointestinal tract. These syndromes are transmitted in an autosomal dominant fashion to offspring, but sporadic forms do exist in which the biological parents lack an identified germline mutation. Despite the nondysplastic histologic characteristics of their polyps, each hamartomatous syndrome carries an elevated risk for cancer at specific organ sites. Several genes have been identified as mutated in the germline from these syndromes, and they provide clues to the pathogenesis of the polyps and may explain some of the elevated cancer risk. Pathways involved in the hamartomatous syndromes include those of vascular endothelial growth factor, the transforming growth factor beta superfamily, and antagonizing the effects of Akt/protein kinase B. (C) 2002 Lippincott Williams & Wilkins, Inc.