Juvenile polyposis syndrome

Overview

Juvenile polyposis syndrome (JPS) is a rare inherited condition characterized by the development of multiple benign growths (juvenile polyps) in the gastrointestinal (GI) tract, particularly in the colon, rectum, stomach, and small intestine. Despite the name, "juvenile" refers to the type of polyp rather than the age of onset, although the condition often presents in childhood or adolescence. While the polyps are initially benign, individuals with JPS have an increased risk of developing gastrointestinal cancers, especially colorectal cancer, if not properly monitored and treated.

Causes

Juvenile polyposis syndrome is caused by mutations in one of two genes: SMAD4 or BMPR1A. These genes play key roles in cell growth regulation and the maintenance of the lining of the gastrointestinal tract. The syndrome follows an autosomal dominant inheritance pattern, meaning that a mutation in just one copy of the gene from either parent is sufficient to cause the disorder. In some cases, the mutation arises de novo (spontaneously), with no family history of the condition.

Symptoms

Symptoms of JPS can vary depending on the number, size, and location of the polyps. Common clinical features include:

• Rectal bleeding or blood in the stool

• Abdominal pain or discomfort

• Diarrhea or changes in bowel habits

• Anemia due to chronic blood loss

• Prolapse of polyps through the anus (especially in young children)

• Malnutrition or failure to thrive (in severe cases)

While some individuals may remain asymptomatic for years, others may present with symptoms early in life, prompting clinical investigation.

Diagnosis

Diagnosing juvenile polyposis syndrome typically involves a combination of clinical evaluation, endoscopic procedures, and genetic testing. Key diagnostic steps include:

• Colonoscopy and upper GI endoscopy to visualize and biopsy polyps

• Histological examination of polyps showing characteristic features of juvenile polyps

• Family history review for hereditary polyposis syndromes

• Genetic testing to identify mutations in SMAD4 or BMPR1A

• Imaging studies or capsule endoscopy to evaluate the small intestine, if needed

Treatment

There is no cure for JPS, but treatment focuses on regular surveillance and polyp removal to reduce cancer risk and manage symptoms. Treatment strategies may include:

• Endoscopic polypectomy: Removal of polyps during colonoscopy or endoscopy

• Surgical intervention: In cases of numerous or large polyps, bowel resection or colectomy may be necessary

• Regular surveillance: Lifelong endoscopic monitoring to detect and remove new polyps before they cause complications

• Iron supplementation: To manage anemia caused by chronic bleeding

• Genetic counseling: For affected individuals and at-risk family members

Prognosis

The prognosis for individuals with juvenile polyposis syndrome depends on early diagnosis, regular monitoring, and timely removal of polyps. With appropriate surveillance and management, many individuals can live healthy lives and significantly reduce their risk of colorectal or gastric cancer. However, without treatment, there is a considerable risk of malignant transformation. The lifetime risk of developing colorectal cancer in JPS is estimated to be 40–50%, underscoring the importance of long-term follow-up and preventive care.