APC Gene Mutation

What is the APC gene?

APC is a type of gene known as a tumor suppressor gene. When the gene works properly, it can keep cancer from developing.

Which cancers are associated with an APC mutation?

People with a mutation in the APC gene have an increased risk for cancer, particularly, colorectal cancer.

APC mutations and their related cancer risks are typically divided into 3 categories:

• Familial adenomatous polyposis (FAP)
• Attenuated FAP (AFAP)
• APC I1307K

The lifetime cancer risks for people with an APC mutation are very different depending on the type of mutation they have. People with FAP and AFAP have a very high risk for cancer. People with an APC I1307K mutation have a slightly increased risk for cancer.

If your genetic test found an APC mutation, it is important to know which type of mutation you have. Speak with a genetics expert to ensure that you have the most up-to-date information about your cancer risks and risk-management options.  

What is FAP? What is AFAP?

"Familial adenomatous polyposis" (FAP) and "attenuated FAP" (AFAP) are caused by mutations in the APC gene. These conditions are 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. AFAP 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.

What is the APC mutation I1307K?

People who test positive for and APC I1307K do not develop FAP. The APC I1307K mutation causes a slightly increased risk for colorectal cancer beginning in adulthood.

This mutation is common in people of Eastern European Jewish ethnicity, occuring in 7% of this population.

The APC I1307K mutation is sometimes also referred to as c.3920T>A or p.Ile1307Lys.

What can people with an APC mutation do?

Risk-management recommendations for people with FAP and AFAP begin at a young age and continue throughout their life. It's important that people seek care from healthcare providers with expertise in managing risk in people with FAP. 

There may be other medical concerns for people with FAP or AFAP, including cancer risks for children beginning at a young age.

For people with an APC I1307K mutation, risk-management recommendations may include more frequent colorectal cancer screenings beginning at a slightly younger age than people in the general population.

If you test positive for an APC mutation, you should inform your close blood relatives (first-, second-, and third-degree relatives) about your test results and encourage them to speak with a genetics expert. 

More detailed information for people with inherited APC mutations is highlighted below.