SMAD4 and BMPR1A are genes that help to protect against bowel and stomach polyps and cancer.
Everyone has two SMAD4 genes and two BMPR1A genes (one from their mother, and one from their father). If one of these genes is not working this is known as having a faulty SMAD4 or BMPR1A gene, or having a SMAD4 or BMPR1A mutation. People with a faulty SMAD4 or BMPR1A gene are known to have Juvenile Polyposis syndrome.
People with a faulty SMAD4 gene may also have a condition known as Hereditary Haemorrhagic Telangiectasia (HHT).