Alternative Names
BMPR1A-related juvenile polyposis; juvenile intestinal polyposis; SMAD4-related juvenile polyposis
Symptoms & Characteristics
Juvenile polyposis syndrome (JPS) is a disorder characterized by multiple noncancerous (benign) growths called juvenile polyps. These growths occur in the gastrointestinal tract, specifically in the stomach, small intestine, colon, and rectum. Juvenile refers to the type of polyp, not the age at which polyps develop. People with juvenile polyposis syndrome typically develop polyps during the first two decades of life. The number of polyps varies from only a few to hundreds, even among affected people in the same family. Polyps may cause gastrointestinal bleeding, a shortage of red blood cells (anemia), abdominal pain, and diarrhea.
Approximately 15% of affected people have other abnormalities, such as a twisting of the intestines (intestinal malrotation), heart or brain abnormalities, an opening in the roof of the mouth (cleft palate), extra fingers or toes (polydactyly), and abnormalities of the genitalia or urinary tract.
Juvenile polyposis syndrome is diagnosed when a person has any one of the following: (1) more than five juvenile polyps of the colon or rectum, (2) juvenile polyps in other parts of the gastrointestinal tract, or; (3) any number of juvenile polyps and one or more affected family member.
Three types of juvenile polyposis syndrome have been described, based on the signs and symptoms of the disorder: juvenile polyposis of infancy, juvenile polyposis of infancy and juvenile polyposis coli.
Juvenile polyposis of infancy is characterized by polyps that occur throughout the gastrointestinal tract during infancy. Juvenile polyposis of infancy is the most severe form of the disorder and is associated with the poorest outcome. Children with this type may develop a condition called protein-losing enteropathy. This disorder results in severe diarrhea, failure to gain weight and grow at the expected rate (failure to thrive), and general wasting and weight loss (cachexia).
Generalized juvenile polyposis is diagnosed when polyps develop throughout the gastrointestinal tract. In juvenile polyposis coli, polyps only develop in the colon. People with generalized juvenile polyposis and juvenile polyposis coli typically develop polyps during childhood.
Most juvenile polyps are benign, but there is a chance that polyps can turn cancerous (malignant). It is estimated that people with juvenile polyposis syndrome have a 9% to 50% risk of developing a cancer of the gastrointestinal tract. The most common type of cancer seen in people with juvenile polyposis syndrome is colorectal cancer. The incidence of gastric (stomach) cancer is 21% in affected people with gastric polyps.
Treatment
Early diagnosis, routine surveillance and treatment of juvenile polyposis syndrome may help to manage some of the symptoms and sometimes prevent related problems.
How Common Is It?
Approximately 1 in 100,000 individuals worldwide are affected with juvenile polyposis syndrome.
Genetics & Inheritance
Juvenile polyposis syndrome is caused by mutations in the BMPR1A and SMAD4 genes.
- Approximately 20% of affected people have mutations in BMPR1A gene.
- Approximately 20% of affected people have mutations in SMAD4 gene.
Other genes may also be associated with juvenile polyposis syndrome.
Juvenile polyposis syndrome is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In approximately 75% of cases, an affected person inherits the mutation from an affected parent. The remaining 25% of cases result from new mutations in the gene and occur in people with no family history of the disorder.
Genetic Testing
Clinical genetic testing for juvenile polyposis syndrome may be available through an in person genetic consultation for people who are considered at risk. Use our find a genetic professional directory to locate a trained genetic professional in your area.
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