What is Juvenile Polyposis?

Learn About Juvenile Polyposis to Better Manage This Condition

Colon Polyps
Polyps in colon. Juan Gartner/Photo Science Library/Getty Images

Juvenile polyposis (JP) increases risk of colon cancer if it's not managed properly. But learning about JP can help you make informed decisions about how best to cope with the condition.

Juvenile Polyposis and Genetic and Familial Colon Cancers

Most colon cancers, about 75%, are considered sporadic cases. Sporadic means that they have no known genetic cause or family history. This leaves approximately 25% of colon cancers that can be traced to a specific genetic problem or to a family history of the disease.

One genetic cause of colon cancer is called juvenile polyposis (JP) or juvenile polyposis syndrome (JPS). The word "juvenile" refers to the type of polyp, rather than the age at which polyps first develop. People don't often get the polyps as juveniles, but instead they develop polyps in their colon as young adults, around 20 years old. If left untreated, these polyps may develop into colon cancer.

Is Juvenile Polyposis the Same as Hereditary Hemorrhagic Telangiectasia

Some health experts consider JP to be a form of a disease called hereditary hemorrhagic telangiectasia. Other health experts consider JP to be a completely separate disease. Around 20% of people who have the genetic changes that cause JP also have hereditary hemorrhagic telangiectasia (HHT). This overlap between JP and HHT contributes to the confusion in naming and describing both conditions.

When JP and HHT appear together in a single person, it is referred to as "combined syndrome of juvenile polyposis and hereditary hemorrhagic telangiectasia" or JPS/HHT.

In addition to the colon polyps associated with JPS, people who also have HHT develop malformations in their blood vessels. These vessel abnormalities may lead to a variety of medical problems, including frequent nose bleeds and bleeding in the gastrointestinal tract.

Juvenile Polyposis and Cancer Risk

The most common cancer associated with JP is colon cancer, but cancers can occur in the stomach, small intestine, and pancreas too.

If the colon polyps are not removed, around 20% of people with JP will develop colon cancer by age 35. About 70% of people with JP will develop colon cancer by age 60. Because colon cancer risk is so high in people with JP, surgery to remove the colon may be recommended.

How Common is Juvenile Polyposis?

Health experts aren't sure how common JP and HHT are in the general population. They estimate that between 1 in 5,000 and 1 in 10,000 people are affected by these conditions. However, these numbers include all forms of hereditary hemorrhagic telangiectasia syndrome - JPS/HHT as well as the three types of HHT that are not associated with JP. This means that only a small portion of the total hereditary hemorrhagic telangiectasia cases occur as the JP type. The bottom line is that as a cause of colon cancer in the US, JP is quite rare.

How is Juvenile Polyposis Inherited?

JP is passed from parents to children due to changes in either the SMAD4 or the BMPR1A gene. Genes are the instruction manual for building and running the human body.

Nearly every cell in our bodies contains two copies of each gene. One copy comes from your mother and one copy comes from your father. In this way, if a mother or a father has changes in one or both copies of their SMAD4 or their BMPR1A gene, they may pass these changes on to their child, resulting in the child having JP.

For some diseases, if one of the two gene copies is damaged or missing, the other, good copy, will function normally and there will be no disease or no increased risk of disease. This is called an autosomal recessive pattern.

For other diseases, including juvenile polyposis, if even one copy of a pair of genes is damaged or missing, this is enough to increase disease risk or cause the disease. This is called an autosomal dominant pattern.

Your Best Defense Against Juvenile Polyposis

If you find out that you have JP, talk to your doctor about getting a referral to see a genetic counselor. Your doctor can help you find a qualified genetic counselor in your area or you can search the National Society of Genetic Counselors website to locate genetic counseling resources.

Seeing a genetic counselor is important because there are different changes to the SMAD4 and BMPR1A genes that cause JP. The changes that are present in your gene may determine your risk for developing colon or other cancers.

It is important to know your own personal risk so you can develop a plan to manage it. For example, if you have a form of JP that greatly increases the odds of developing colon cancer early in life, you may choose to go through surgery to remove your colon as soon as possible to prevent cancer.

The second important step you can take is to talk to your doctor about any other health risks that may be associated with having JP. You can work together to develop a plan to best manage your health, taking into account the new information regarding your diagnosis of juvenile polyposis.


American Society of Colon & Rectal Surgeons. Hereditary Colorectal Cancer Registries. 

Brosens LA, van Hattem A, Hylind LM, Iacobuzio-Donahue C, Romans KE, Axilbund J, Cruz-Correa M, Tersmette AC, Offerhaus GJ, Giardiello FM. Risk of colorectal cancer in juvenile polyposis. Gut 2007 56:965-67.

Gene Reviews: Juvenile Polyposis Syndrome. NCBI, U.S. National Llibrary of Medicine. Last Revision Dec. 3, 2015. 

Genetic and Rare Diseases Information Center. 

Genetics Home Reference. Hereditary Hemorrhagic Telangiectasia. 

OncoLink. Risk of colorectal cancer is increased in patients with juvenile polyposis. 

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