Hereditary Cancer and Genetic Testing

General information for people with an inherited APC mutation

Both men and women can carry a mutation in the APC gene and pass the mutation to any of their children. Mutations in the APC gene increase the risk for cancer. The lifetime cancer risks and risk management recommendations depend on several factors, including the location and type of APC mutation. APC mutations and their related cancer risks are typically divided into 3 categories:

See our Cancer Risk section for more information.  There are guidelines for screening and prevention for certain cancers in people with an APC mutation. See our Risk Management section for more information about screening options in people with APC mutations.

People with an APC mutation who have been diagnosed with cancer may qualify for specific clinical trials. Visit our Cancer Treatment section to learn if there are any treatment clinical trials enrolling people with an APC mutation. 

Because of the high lifetime risk and early onset of medical issues with FAP and AFAP, people of reproductive age may wish to speak with a genetics expert about options related to family planning. See our Other Considerations section for more information.

About 30% of people who test positive for an APC mutation did not inherit the mutation from either parent. These are known as de novo mutations. A person with a de novo mutation in the APC gene can pass the mutation on to their children.  
 

Familial adenomatous polyposis (FAP)

FAP is caused by mutations in the APC gene. This condition is rare, occurring in about one in 10,000 people. People with FAP may develop hundreds to thousands of polyps in their colon and rectum, often beginning in their teenage years or early adulthood. Risk management recommendations for people with FAP begin at a young age and continue throughout their life.
 

Attenuated FAP (AFAP)

Attenuated FAP is a milder subset of FAP that tends to begin at a later age than FAP. People with AFAP may develop dozens rather than hundreds or thousands of colon and rectal polyps. Risk management options are similar to those for people with classic FAP.

 

APC variant I1307K

A variant in the APC gene, known as I1307K (or sometimes called c.3920T>A or p.Ile1307Lys) is common in people of ancestry; about 7 percent of people will have this variant. People who test positive for I1307K do not develop FAP. They do have a slightly increased risk for colorectal cancer beginning in adulthood and risk management recommendations include more frequent screenings beginning at a slightly younger age than people in the general population.

Last updated February 08, 2022