Search

The hamartomatous polyposis syndromes are a set of clinically distinct disorders characterized by the occurrence of hamartomatous polyps in the gastrointestinal tract. These syndromes include juvenile polyposis syndrome, Peutz-Jeghers syndrome, and PTEN hamartoma tumor syndrome. Although each of the syndromes has distinct phenotypes, the hamartomatous polyps can be challenging to differentiate histologically. Additionally, each of these syndromes is associated with increased lifetime risks of gene-specific and organ-specific cancers, including those outside of the gastrointestinal tract. Germline pathogenic variants can be identified in a subset of individuals with these syndromes, which facilitates molecular diagnosis and subsequent gene-enabled management in the setting of genetic counseling. Although the malignant potential of hamartomatous polyps remains elusive, timely recognition of these syndromes is important and enables presymptomatic cancer surveillance and management before symptom exacerbation. Presently, there are no standard agents to prevent the development of polyps and cancers in the hamartomatous polyposis syndromes., (Copyright © 2023 AGA Institute. Published by Elsevier Inc. All rights reserved.)

The gastrointestinal hamartomatous polyposis syndromes are rare, autosomal dominant disorders associated with an increased risk of benign and malignant intestinal and extraintestinal tumors. They include Peutz-Jeghers syndrome, juvenile polyposis syndrome, the PTEN hamartoma tumor syndrome (including Cowden's syndrome and Bannayan-Riley-Ruvalcaba syndrome), and hereditary mixed polyposis syndrome. Diagnoses are based on clinical criteria and, in some cases, confirmed by demonstrating the presence of a germline pathogenic variant. The best understood hamartomatous polyposis syndrome is Peutz-Jeghers syndrome, caused by germline pathogenic variants in the STK11 gene. The management is focused on prevention of bleeding and mechanical obstruction of the small bowel by polyps and surveillance of organs at increased risk for cancer. Juvenile polyposis syndrome is caused by a germline pathogenic variant in either the SMAD4 or BMPR1A genes, with differing clinical courses. Patients with SMAD4 pathogenic variants may have massive gastric polyposis, which can result in gastrointestinal bleeding and/or protein-losing gastropathy. Patients with SMAD4 mutations usually have the simultaneous occurrence of hereditary hemorrhagic telangiectasia (juvenile polyposis syndrome-hereditary hemorrhagic telangiectasia overlap syndrome) that can result in epistaxis, gastrointestinal bleeding from mucocutaneous telangiectasias, and arteriovenous malformations. Germline pathogenic variants in the PTEN gene cause overlapping clinical phenotypes (known as the PTEN hamartoma tumor syndromes), including Cowden's syndrome and related disorders that are associated with an increased risk of gastrointestinal and colonic polyposis, colon cancer, and other extraintestinal manifestations and cancers. Due to the relative rarity of the hamartomatous polyposis syndromes, recommendations for management are based on few studies. This U.S Multi-Society Task Force on Colorectal Cancer consensus statement summarizes the clinical features, assesses the current literature, and provides guidance for diagnosis, assessment, and management of patients with the hamartomatous polyposis syndromes, with a focus on endoscopic management., (Copyright © 2022 American Gastroenterological Association, the American Society for Gastrointestinal Endoscopy, and The American College of Gastroenterology. Published by Elsevier Inc. All rights reserved.)

Hamartomatous polyposis syndromes (HPS) account for a small but appreciable proportion of inherited gastrointestinal cancer predisposition syndromes; patients with HPS have an increased risk for colon and extracolonic malignancies. We present a unique case of familial juvenile polyposis syndrome associated with gastrointestinal ganglioneuromas of unknown etiology. The patient was tested for HPS-associated genes, but no mutation was detected. Exome sequencing identified a germline heterozygous mutation in SMAD9 (SMAD9(V90M)). This mutation was predicted to be an activating mutation. HEK cells transfected to express SMAD9(V90M) had reduced expression of phosphatase and tensin homolog; this reduction was also observed in a polyp from the patient. We have therefore identified a new susceptibility locus for HPS. Patients with hamartomatous polyposis in the colon associated with ganglioneuromatosis should be referred for genetic assessments., (Copyright © 2015 AGA Institute. Published by Elsevier Inc. All rights reserved.)