Juvenile Polyposis Syndrome (JPS)

At a glance…

• Caused by differences in the BMPR1A or SMAD4 genes
• Leads to multiple “juvenile” polyps in the bowel or stomach
• Increases risk of bowel and stomach cancer if not managed
• Can affect both children and adults
• Each child of an affected parent has a 50% chance of inheriting JPS

What the syndrome is and what it means for you and your family

Juvenile Polyposis Syndrome (JPS) is a rare inherited condition where multiple polyps develop in the bowel and sometimes the stomach. These polyps can bleed, cause tummy problems, or — if left untreated — increase the risk of cancer.
Although the name “juvenile” may sound like it only affects children, it actually refers to how the polyps look under a microscope. JPS can affect both children and adults. Because it is inherited, other family members may also be at risk.

What symptoms to look out for

• Bleeding from the bottom
• Anaemia (low iron, tiredness, or shortness of breath)
• Diarrhoea or tummy pain
• In rare cases, bowel blockages

About the gene differences

JPS is usually caused by differences in one of two genes: BMPR1A or SMAD4. These genes help control cell growth. When they do not work as expected, polyps can develop in the digestive system.

How it runs in families

JPS is usually inherited in an “autosomal dominant” way. If one parent has the condition, each child has a 50% chance of inheriting it. Sometimes JPS can appear for the first time in a family with no previous history.

How it is diagnosed

• Colonoscopy and/or endoscopy to look for polyps
• Genetic testing to confirm the condition
• Family history can provide important clues

Screening and treatment

• Regular colonoscopies and endoscopies to monitor and remove polyps
• Monitoring for anaemia and other complications
• In some cases, screening for stomach and small bowel polyps is also recommended

Possible surgery options

If there are too many polyps to remove safely during screening, surgery may be recommended to remove part of the bowel. This helps reduce cancer risk.

Health and lifestyle tips

• Eat a balanced diet rich in fruit, vegetables, and whole grains
• Stay active to support your overall health
• Do not ignore symptoms — regular check-ups are the most important step
• If you have the SMAD4 gene difference, you may also need checks for hereditary haemorrhagic telangiectasia (HHT), a related condition that can affect blood vessels

Planning a family

Genetic counselling can help you understand your options, including pre-implantation testing if you are planning a pregnancy.