Juvenile polyposis syndrome
Overview
Juvenile polyposis syndrome (JPS) is a hereditary condition that is characterized by the presence of hamartomatous polyps in the digestive tract. Hamartomas are noncancerous masses of normal tissue that build up in the intestines or other places. These masses are called polyps if they develop inside a body structure, such as the intestines. The term juvenile polyposis refers to the type of polyp (juvenile polyp) that is found after examination under a microscope, rather than the age at which people are diagnosed with JPS.
Symptoms
Polyps in gastrointestinal tract
Causes
JPS is a genetic condition. This means that the risk for polyps and cancer can be passed from generation to generation in a family. Two genes have been linked to JPS. They are called BMPR1A and SMAD4. A mutation (alteration) in either the BMPR1A gene or the SMAD4 gene makes a person more likely to develop juvenile polyps and cancer of the digestive tract over his or her lifetime.
Diagnosis
A diagnosis of JPS is assumed if a person's symptoms and history fits one of the three categories listed above. People who have JPS can have a blood test to look for a mutation in the BMPR1A gene or the SMAD4 gene. If a specific gene mutation is found, other family members will be diagnosed with JPS if they are tested and have the same gene mutation. It appears likely that there are other genes associated with JPS that have not yet been identified, so a blood test result that comes back as "negative" (meaning a gene mutation cannot be found) does not mean that a person does not have JPS.
Prognosis
Solitary polyps has no significant risk of cancer. But multiple polyps (>5), polyposis syndrome, of the colon carry a 10% risk of developing into a cancer. This is mainly because of juvenile polyps developing adenomatous tissue.