About Mutations in the APC Gene

This information explains how having a mutation in the APC gene may affect you and your family. It does not apply to people who have the specific APC gene mutation called I1307K. For more information on this specific mutation, read About the APC I1307K Gene Mutation.

In this resource, the word “family” means family members related to you by blood. They are not related to you through marriage or adoption.

Your APC gene normally helps prevent cancers. A mutation in this gene causes it to stop working like it should. This increases your risk for certain types of cancers.

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What is my cancer risk if I have an APC mutation?

Most APC mutations cause a condition called Familial Adenomatous Polyposis (FAP). FAP increases your risk for certain types of cancers, including colorectal (colon and rectal) cancer.

FAP increases your risk of developing hundreds to thousands of polyps (growths of tissue) in your colon and rectum. These polyps can lead to an increased risk for colorectal cancer.

FAP may also increase your risk for other cancers, but this is less common. Examples of less common cancers linked to FAP are:

  • Small intestine (small bowel) cancer
  • Thyroid cancer
  • Brain cancer
  • Pancreatic cancer
  • Bile duct cancer
  • Hepatoblastoma (a rare type of liver cancer) in childhood
  • Desmoid tumors (noncancerous tumors in your connective tissue) in your abdomen (belly)

An APC mutation may also cause noncancerous eye and skin growths.

As we learn more about these mutations, we may learn they increase the risk for other types of cancers. Your genetic counselor will give you more information about your cancer risk if you have a mutation.

For more information, readHereditary Colon Cancer and Polyposis.

For more information, read Hereditary Colon Cancer and Polyposis - www.mskcc.org/genetics/colon-cancer-polyposis

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What can I do about my cancer risk if I have an APC mutation?

If you have a mutation, your genetic counselor will review your results and your personal and family history of cancer and give you cancer screening recommendations.

They may recommend you start having cancer screenings at a younger age, have them more often than most people, or get specialized screenings to help find cancer as early as possible.

Some examples of these cancer screenings include:

  • Getting colonoscopies starting at an earlier age and more often than most people.
  • Getting an upper endoscopy (a procedure that lets your doctor see inside your stomach and small intestine).
  • Having an ultrasound of your thyroid gland to check for thyroid cancer.

If you’re having surgery for colon cancer or polyps, your genetic counselor may recommend you have extra colon tissue removed to prevent colon cancer.

Your genetic counselor will also talk with you about whether there are any other screening or prevention options that may be right for you.

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What happens if I don’t have an APC mutation?

If you don’t have a mutation, your genetic counselor will review your personal and family history and talk with you about the general cancer screening guidelines you should follow.

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What does an APC mutation mean for my blood relatives?

If you have a mutation, your biological parents, siblings, and children each have a 50% chance of having the same mutation. This means there’s an equal chance they will or won’t have the mutation. Your distant family members may also be at risk for having the same mutation.

Males and females have an equal chance of passing down a mutation in their family. You only need to inherit a mutation from one parent to have an increased risk for cancer.

Your genetic counselor will review your family history and talk with you about whether they recommend genetic testing for your blood relatives.

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Contact Information

If you have any questions or concerns, talk with a genetic counselor in the Clinical Genetics Service. You can reach them Monday through Friday from 9:00 am to 5:00 pm  at 646-888-4050.
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