Juvenile polyposis syndrome

Other Names: JPS; Polyposis juvenile intestinal; PJI; Juvenile intestinal polyposis; JIP; Polyposis familial of entire gastrointestinal tract

Juvenile polyposis syndrome (JPS) is a disorder characterized by having a susceptibility to developing hamartomatous polyps in the gastrointestinal (GI) tract. A hamartomatous polyp is a benign (noncancerous) tumor-like malformation made up of an abnormal mixture of cells and tissues. In JPS, these polyps can occur in the stomach, small intestine, colon, and rectum. The term "juvenile" refers to the type of polyp and not the age at which the polyps develop.

Most people with JPS have some polyps by the age of age 20. The number of polyps in affected people vary. While some people may have only four or five polyps over their lifetime, others (even in the same family) may have more than 100. If the polyps are left untreated, they can result in bleeding and anemia. Most juvenile polyps are benign, although over time they can become cancerous.

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 members. Single juvenile polyps are relatively common in children and are not characteristic of juvenile polyposis syndrome.

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Epidemiology

Juvenile polyposis syndrome occurs in approximately 1 in 100,000 individuals worldwide.

Riskfactors

In families with JPS, the risk for developing a GI cancer ranges from 9% to 50%. Most of this risk is due to colon cancer. The incidence of colorectal cancer in people with JPS is 17%-22% by the age of 35 and as high as 68% by the age of 60.

Types

Three types of juvenile polyposis syndrome have been described, based on the signs and symptoms of the disorder. 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 condition results in severe diarrhea, failure to gain weight and grow at the expected rate (failure to thrive), and general wasting and weight loss (cachexia).

Another type called generalized juvenile polyposis is diagnosed when polyps develop throughout the gastrointestinal tract.

In the third type, known as juvenile polyposis coli, affected individuals develop polyps only in their colon. People with generalized juvenile polyposis and juvenile polyposis coli typically develop polyps during childhood.

Cause

Mutations in the BMPR1A and SMAD4 genes cause juvenile polyposis syndrome. These genes provide instructions for making proteins that are involved in transmitting chemical signals from the cell membrane to the nucleus. This type of signaling pathway allows the environment outside the cell to affect how the cell produces other proteins. The BMPR1A and SMAD4 proteins work together to help regulate the activity of particular genes and the growth and division (proliferation) of cells.

Mutations in the BMPR1A gene or the SMAD4 gene disrupt cell signaling and interfere with their roles in regulating gene activity and cell proliferation. This lack of regulation causes cells to grow and divide in an uncontrolled way, which can lead to polyp formation.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

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 percent of cases, an affected person inherits the mutation from one affected parent. The remaining 25 percent of cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Signs and symptoms

People with juvenile polyposis syndrome typically develop polyps before age 20; however, in the name of this condition "juvenile" refers to the characteristics of the tissues that make up the polyp, not the age of the affected individual. These growths occur in the gastrointestinal tract, typically in the large intestine (colon).

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 100% of people have these symptoms

• Juvenile colonic polyposis
• Juvenile gastrointestinal polyposis
• Rectal polyposis

30%-79% of people have these symptoms Abdominal pain(Pain in stomach) Anemia(Low number of red blood cells or hemoglobin) Failure to thrive(Faltering weight) Multiple gastric polyps Small intestinal polyposis

5%-29% of people have these symptoms

• Abnormal facial shape(Unusual facial appearance)
• Chronic fatigue(Chronic extreme exhaustion)
• Clubbing(Clubbing of fingers and toes)
• Clubbing of fingers(Clubbed fingers)
• Colon cancer
• Duodenal adenocarcinoma
• Growth delay(Delayed growth)
• Hamartomatous stomach polyps
• Hematochezia(Rectal bleeding)
• Intellectual disability, mild(Mental retardation, borderline-mild)
• Intussusception
• Large forehead(Increased size of forehead)
• Macrocephaly(Increased size of skull)
• Neoplasm of the small intestine(Small intestine tumor)
• Rectal prolapse(Rectum protrudes through anus)
• Rectocele
• Short chin(Decreased height of chin)
• Spontaneous, recurrent epistaxis(Recurring nosebleed)
• Stomach cancer

Diagnosis

Juvenile polyposis syndrome (JPS) should be suspected in a proband with the following clinical and histopathology features.

Clinical features

• Anemia, rectal bleeding, or prolapse of rectal polyp
• More than one juvenile polyp
• One or more juvenile polyps and a family history of JPS

Note: "Juvenile" refers to the polyp histopathology not the age of onset of polyps.

Histopathology features. Juvenile polyps are hamartomas that develop from an abnormal collection of tissue elements normally present at this site. Juvenile polyps show a normal epithelium with a dense stroma, an inflammatory infiltrate, and a smooth surface with dilated, mucus-filled cystic glands in the lamina propria. Muscle fibers and the proliferative characteristics of adenomas are typically not seen in juvenile polyps.

The diagnosis of JPS is established in a proband with any one of the following clinical features:

• More than five juvenile polyps of the colon or rectum
• Multiple juvenile polyps of the upper and lower GI tract
• Any number of juvenile polyps and a family history of juvenile polyposis

Molecular genetic testing approaches can include BMPR1A and SMAD4 concurrent testing, serial single-gene testing, use of a multigene panel, and more comprehensive genomic testing.

Treatment

Management of JPS includes routine colonoscopy with removal of any polyps to reduce the risk of bleeding, intestinal obstruction, and colon cancer. When the number of polyps is large, removal of all or part of the colon or stomach may become needed. Additional screening can include upper endoscopy, complete blood count, and monitoring for symptoms such as rectal bleeding and/or anemia abdominal pain, constipation, diarrhea, or change in stool size, shape, and/or color.

Prognosis

Most juvenile polyps are benign; however, malignancy can occur. The cumulative lifetime risk of colorectal cancer is 39% in patients with juvenile polyposis syndrome.

NIH genetic and rare disease info

• NIH info on Juvenile polyposis syndrome

Juvenile polyposis syndrome is a rare disease.

Juvenile polyposis syndrome Resources
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