Juvenile polyposis syndrome (JPS) is an autosomal dominant disorder characterized by the occurrence of juvenile polyps and predisposition to cancer of the gastrointestinal tract (GIT). Characteristic feature of juvenile polyps are irregular cystic glands filled with mucus not observed in other colorectal cancer syndromes. Germline mutations in the SMAD4 and BMPR1A genes are found in 40% of the JP individuals. Hereditary hemorrhagic telangiectasia (HHT) and higher frequency of gastric polyposis are associated mostly with SMAD4 mutations.