Juvenile Polyposis syndrome is a genetic condition that leads to ‘juvenile’ type polyps in the bowel and stomach. It can be due to faults (mutations) in the SMAD4 or BMPR1A genes but sometimes the genetic cause is not known. SMAD4 and BMPR1A are genes that help to control cell growth in the lining of the bowel and stomach.
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 gene or a faulty BMPR1A gene, or having a SMAD4 mutation or a BMPR1A mutation.
People with a faulty SMAD4 gene may also have a condition known as Hereditary Haemorrhagic Telangiectasia (HHT).