What is juvenile polyposis syndrome (JPS)?
Juvenile polyposis syndrome (JPS) is a disorder marked by growths, called polyps, which 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.
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.
How common is juvenile polyposis syndrome (JPS)?
JPS is estimated to affect anywhere from 1 in 100,000 to 1 in 160,000 people.
What causes juvenile polyposis syndrome (JPS)?
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% 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% chance of inheriting JPS. About 25% 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% 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)?
JPS may have no symptoms. When the polyps are large or numerous, things you might notice include:
- Bleeding from the rectum
- Blood in your stool
- Cramping/abdominal pain
- Anemia - a shortage of red blood cells causing weakness or fatigue (extreme tiredness)
- Chronic (long-term) weight loss
Sometimes, the polyps are visible coming out of the rectum.