Juvenile polyposis syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Juvenile polyposis syndrome is a disorder characterized by multiple noncancerous (benign) growths called juvenile polyps. 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). The number of polyps varies from only a few to hundreds, even among affected members of the same family. Polyps may cause gastrointestinal bleeding, a shortage of red blood cells (anemia), abdominal pain, and diarrhea. Approximately 15 percent of people with juvenile polyposis syndrome 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 members. Single juvenile polyps are relatively common in children and are not characteristic of juvenile polyposis syndrome.

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, inability to gain weight and grow at the expected rate (faltering weight), 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.

Most juvenile polyps are benign, but there is a chance that polyps can become cancerous (malignant). It is estimated that people with juvenile polyposis syndrome have a 10 to 50 percent 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.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

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 and family implications

From: MedlinePlus Genetics, National Library of Medicine

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.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

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

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Intestinal polyp · Very frequent (99-80%)

A discrete abnormal tissue mass that protrudes into the lumen of the intestine and is attached to the intestinal wall either by a stalk, pedunculus, or a broad base.

Juvenile colonic polyposis · Obligate (100%)

The presence of more than 5 juvenile polyps of the colon. The term juvenile polyps refer to a special histopathology and not the age of onset as the polyp might be diagnosed at all ages. The juvenile polyp has a spherical appearance and is microscopically characterized by overgrowth of an oedematous lamina propria with inflammatory cells and cystic glands.

Juvenile gastrointestinal polyposis · Obligate (100%)

The presence of multiple juvenile polyps in the stomach and intestine. The term juvenile polyps refer to a special histopathology and not the age of onset as the polyp might be diagnosed at all ages. The juvenile polyp has a spherical appearance and is microscopically characterized by overgrowth of an oedematous lamina propria with inflammatory cells and cystic glands. Juvenile polyps are a specific type of hamartomatous polyps.

Rectal polyposis · Obligate (100%)

The presence of multiple rectal hyperplastic/adenomatous polyps.

Abdominal pain · Frequent (79-30%)

An unpleasant sensation characterized by physical discomfort (such as pricking, throbbing, or aching) and perceived to originate in the abdomen.

Anemia · Frequent (79-30%)

A reduction in erythrocytes volume or hemoglobin concentration.

Hamartomatous polyposis · Frequent (79-30%)

Polyp-like protrusions which are histologically hamartomas. These can occur throughout the gastrointestinal tract. Hamartomatous polyps are composed of the normal cellular elements of the gastrointestinal tract, but have a markedly distorted architecture.

Small intestinal polyposis · Frequent (79-30%)

The presence of multiple polyps in the small intestine.

Other findings in the same source

From: Orphanet

Additional reported features include Abnormal facial shape (Occasional (29-5%)); Chronic fatigue (Occasional (29-5%)); Clubbing of fingers (Occasional (29-5%)); Diarrhea (Occasional (29-5%)); Edema (Occasional (29-5%)); Failure to thrive (Occasional (29-5%)); Gastrointestinal hemorrhage (Occasional (29-5%)); Growth delay (Occasional (29-5%)); Hamartomatous stomach polyps (Occasional (29-5%)); Hematochezia (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Juvenile polyposis syndrome is Gastroenterology, with a gastroenterologist as the relevant type of clinician. General physician / Family Medicine; paediatrician for children. Referral depends on symptoms.

Additional services that may be relevant, depending on the findings, include: Clinical Genetics.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Which digestive symptoms or nutritional changes matter most?
• What question would an endoscopy, scan or laboratory test answer if one is proposed?
• How should persistent pain, bleeding or difficulty eating be followed up?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Juvenile polyposis syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.