What is juvenile polyposis syndrome?

Juvenile polyposis syndrome (JPS) is a disorder marked by growths, called polyps, that grow on the lining of the gastrointestinal (GI) tract. These polyps can occur anywhere in the GI tract, from the stomach to the rectum.

In JPS, the word “juvenile” refers to the way the polyps look under the microscope, and not to the age of the people who get the disorder. However, most people develop symptoms of JPS by the time they are 20 years old. JPS is estimated to affect anywhere from 1 in 16,000 to 1 in 100,000 people.

The polyps in JPS most often grow in the large intestine (colon) and rectum, but can also grow in the stomach and, more rarely, the small intestine. A person with JPS can have a few polyps or more than a hundred. The polyps can vary in shape and size. They may be flat or on a stalk.

What causes juvenile polyposis syndrome?

JPS is a genetic disorder, which means it is caused when something is wrong with a gene that tells your GI tract how to develop. A problem or defect in the gene function can disrupt cell growth and death and the way genes work together. This can cause the normal tissue of the GI tract to grow in an uncontrolled way, which can lead to polyps forming.

Most cases of JPS are caused by a gene change (mutation) that is passed down from one of the parents to the baby. About 75 percent of people with JPS have a family history of the disorder. If one of your parents has a gene with the defect, you and your brothers and sisters have a 50 percent chance of inheriting JPS. About 25 percent of the time, the gene does not get inherited but occurs at the time of formation of the baby.

Two different genes (BMPR1A and SMAD4) have been linked to JPS. Only one is needed to get the disorder. In about 50 to 60 percent of people who have JPS, there is a defect on one of these two genes. People who have an SMAD4 mutation are at risk of having another syndrome called hereditary hemorrhagic telangiectasia (HHT).

What are the symptoms of juvenile polyposis syndrome?

JPS may have no symptoms. When the polyps are large or numerous, things you might notice include:

Sometimes, the polyps are visible coming out of the rectum.

How common is juvenile polyposis syndrome?

JPS is estimated to affect anywhere from 1 in 16,000 to 1 in 100,000 people.

How is juvenile polyposis syndrome diagnosed?

JPS is diagnosed if any of these are true:

  • You have five or more juvenile polyps in your colon and rectum.
  • You have juvenile polyps all over your GI tract.
  • You have any juvenile polyps and a family history of JPS.

If the doctor suspects that you have polyps, he or she will do an endoscopic exam, called a colonoscopy. This is the use of a long tube with a camera and a light at the end that is inserted into your rectum to look for polyps in your lower GI tract. (A different type of endoscopy is used to look at your upper GI tract.) If only a few polyps are found, they are removed during a colonoscopy and studied under the microscope.

If you have a family history of JPS or if your polyps are found to be juvenile polyps, you can have a blood test that will be used to look for the defect on one of the identified genes. This can tell the doctor if you have JPS.

How is juvenile polyposis syndrome treated?

There are no medicines to treat JPS. If there are just a few polyps, they can be removed during an endoscopic examination. To relieve symptoms, or if a large number of polyps are present, part of the stomach and intestine might need to be removed.

The most important part of treating a person with JPS is paying attention. Screening recommendations include the following:

  • Screening starts with continuous monitoring for symptoms in people with JPS.
  • Screening including a blood test, colonoscopy, and an upper endoscopy should be done by the time the person with JPS is 15 or when symptoms first appear. If results are negative, screening should be repeated in three years.
  • If only a few polyps are found, polyps should be removed and screening should be done every year until no polyps are found. Then screening can be done every three years.
  • If surgery was needed, screening should be done on a yearly basis until no more polyps are found, then screening can be done every three years.

What is the outlook for people who have juvenile polyposis syndrome?

People who have JPS have a 9 to 50 percent risk of developing cancer in the GI tract. It usually affects the colon, but can occur in the small intestine, stomach, or pancreas. This makes screening and prompt removal of polyps so important.

There is a strong link between JPS and HHT in people who have an SMAD4 mutation. Additional HHT-related tests and screening are indicated in patients where the JPS is due to an SMAD4 mutation.

Can juvenile polyposis syndrome be prevented?

JPS is an inherited disease so it is not possible to prevent it. However, increased awareness, education and screening help to find JPS early, when polyps can be removed and any cancer can be treated at its earliest stages or even prevented. 

When should I call my health care provider?

Call your health care provider if you have the symptoms of JPS, especially blood in your stool. Be sure to tell your provider if you have a family history of polyps or JPS, so that screening can be done at the right times.


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