What is Familial Adenomatous Polyposis (FAP)?
Familial adenomatous polyposis, often called FAP, is a rare inherited condition that causes many polyps to grow in the colon and rectum. Polyps are small growths that form in the lining of the digestive tract. While these growths start out noncancerous, they can become cancerous over time if they are not treated.
FAP is caused by changes in the APC gene, which normally helps control how cells grow. The condition often develops at a young age, which is why early screening and ongoing care are important.
FAP is usually inherited from a parent. A child of someone with FAP has a 50% chance of inheriting the condition. In some cases, the gene change happens for the first time in a family without a known history of the disease.
There is also a milder form called attenuated FAP (AFAP), which causes fewer polyps and may lead to cancer later in adulthood.
Symptoms
Many people with FAP develop polyps during their teenage years, although symptoms may not appear right away. As the condition progresses, symptoms can become more noticeable.
Possible symptoms and related findings include:
- Blood in the stool
- Abdominal pain or cramping
- Diarrhea or changes in bowel habits
- Unexplained weight loss
- Large numbers of colon or rectal polyps
- Skin cysts or noncancerous growths
- Bone growths or dental changes
How is it diagnosed?
Healthcare providers often diagnose FAP through a combination of family history, physical evaluation, and screening tests. Colonoscopy is commonly used to look for polyps in the colon and rectum.
Genetic testing can help confirm changes in the APC gene and identify family members who may also be at risk. Because FAP can affect other areas of the body, providers may recommend additional imaging or endoscopy tests to monitor overall health.
People with a family history of FAP may begin screening earlier than the general population.
How is it treated?
Treatment focuses on lowering the risk of colorectal cancer and monitoring for related health concerns. Providers may remove polyps during colonoscopy when possible, but many people with classic FAP eventually need surgery to remove part or all of the colon.
After treatment, ongoing monitoring remains important because polyps and other complications can still develop. Care plans may also include screening for cancers or growths outside the colon.
Genetic counseling can help individuals and families better understand inherited risks and make informed healthcare decisions.
