Juvenile polyposis/hereditary haemorrhagic telangiectasia syndrome (SMAD4 gene)
OMIM number: 175050
Comments closing date: 08/05/2026
Juvenile polyposis/hereditary haemorrhagic telangiectasia syndrome is a genetic condition caused by changes in the SMAD4 gene. This gene helps control cell growth and blood vessel development. When it does not function properly, individuals may develop multiple benign growths (polyps) in the stomach and intestines (juvenile polyposis) and abnormal blood vessels (hereditary hemorrhagic telangiectasia, HHT). Polyps can cause bleeding, anaemia, abdominal pain, and increase the risk of gastrointestinal cancers. HHT can cause frequent nosebleeds and abnormal blood vessel connections (arteriovenous malformations, AVMs) in organs such as the lungs, liver and brain, which can lead to serious complications including stroke or internal bleeding. The condition affects multiple organ systems and requires lifelong medical monitoring.
