MUTYH-Associated Polyposis (MAP)

What is MUTYH-associated polyposis (MAP)?

MUTYH-associated polyposis (MAP) is a rare, hereditary (inherited) condition that causes polyps (abnormal tissue growths) in parts of your body. Polyps aren’t cancer, but some can turn into cancer if they aren’t removed.

MAP often causes numerous polyps to grow in your colon and rectum. Polyps can also form in your small intestine and stomach.

Is MUTYH-associated polyposis a cancer risk?

If you have MAP, you have a significantly higher risk of getting colorectal cancer than someone without the condition. Approximately half of all people with MAP have colorectal cancer at the time of their MAP diagnosis. Most of these cancers occur between the ages of 40 and 60, but some appear sooner. You may also be at risk of duodenal cancer and other cancers outside your gastrointestinal (GI) tract.

What is the life expectancy for someone with MUTYH-associated polyposis?

Many people with MAP can have a normal life expectancy if they receive early and regular cancer screenings. The key is to find polyps early so they can be removed before they turn into cancer.

What are the signs and symptoms of MUTYH-associated polyposis?

MAP doesn’t cause any symptoms that you can see or feel. You may have polyps inside your digestive system, but these often don’t cause symptoms. Polyps alone aren’t a reliable sign of MAP because:

• Many people have polyps but don’t have MAP.
• Other genetic conditions, like familial adenomatous polyposis (FAP), can also cause colorectal polyps. Only genetic tests can determine whether you have MAP, FAP or a different genetic condition.
• Some people with MAP don’t have any polyps at the time of their diagnosis.

What causes MUTYH-associated polyposis?

MAP is caused by an inherited mutation (change) to the MUTYH gene (also called the MYH gene). This condition is autosomal recessive, which means you must inherit the gene mutation from both of your parents. If you inherit the mutation from only one parent, you won’t have MAP but are a MAP “carrier.” Being a carrier means you could pass MAP onto your child if their other biological parent is also a carrier.

Approximately 1% to 2% of all people are MAP carriers. Carriers have a slightly higher risk of getting colorectal cancer, but it’s not as high as people with MAP.

How is MUYTH-associated polyposis inherited?

If both biological parents are MAP carriers, their children have a:

• 1 in 4 (25%) chance of not inheriting a MUTYH gene mutation. They won’t have the disease and can’t pass the MUTYH gene mutation onto their children.
• 2 in 4 (50%) chance of being a carrier. They wouldn’t have MAP but could pass the MUTYH gene mutation onto their own children.
• 1 in 4 (25%) chance of inheriting the mutation from both parents. They would have MAP and will pass at least one MUTYH gene mutation onto their children.

How is MUTYH-associated polyposis diagnosed?

Diagnosing MAP usually requires multiple steps. Your provider may start by taking a detailed family history. They’ll ask you about cancers and health conditions that your biological parents, grandparents and siblings have had.

If your provider suspects you could have a genetic condition, they may recommend genetic tests. These tests can identify the MUYTH gene mutation and other genetic conditions that raise your risk of certain cancers.

Your provider may recommend genetic testing if:

• FAP, MAP or other genetic conditions run in your family.
• You have a strong family history of colorectal cancer.
• One or more of your siblings have had multiple colorectal polyps, but your parents haven’t (indicating that your parents could be carriers).

If your genetic tests show you have MAP or are a carrier, your provider will talk with you about your next steps for cancer screenings. You should also tell your family members about your diagnosis so they can do genetic testing if it’s recommended.

How is MUTYH-associated polyposis treated?

There’s no cure for MAP. However, many tests and therapies can help you prevent cancer or treat it in the early stages.

If you have MAP, you may need early and more frequent screening tests to check for cancer, including:

• Colonoscopy: During a colonoscopy, your provider uses a special lighted tube with a camera to view the inside of your colon and rectum. A colonoscopy is the best way to find and remove colorectal polyps. Begin your colonoscopies at age 20 or 10 years before the youngest colorectal cancer diagnosis in your family (whichever is earlier).
• Upper endoscopy: An upper endoscopy allows your provider to view and remove polyps in your stomach and duodenum (upper part of your small intestine). Start getting upper endoscopies at age 25 or earlier if you already have confirmed colorectal polyps.

Can MUTYH-associated polyposis be prevented?

There’s no way to prevent the MUTYH gene mutation. But assisted reproductive techniques can lower the risk of a future child inheriting MAP. In vitro fertilization (IVF) with preimplantation genetic diagnosis (PGD) can boost your chances of having a child without this hereditary condition. With this procedure, your provider tests the embryo for genetic conditions before implanting it in your uterus.

There are many financial and emotional considerations to make before having IVF with PGD. See a qualified reproductive endocrinologist to discuss this option.

What can I expect if I have MUTYH-associated polyposis?

If you have MAP, you’ll need earlier and more frequent cancer screenings. But with the right medical care, you can live a healthy life. See your provider regularly so you can discuss the best ways to prevent cancer.

How do I take care of myself with MUTYH-associated polyposis?

Knowing you have a higher risk of cancer can lead to mental health conditions like anxiety or depression. If you have mental health concerns, don’t try to cope with them on your own. Treatments and support are available, from talk therapy to medications.

You can also look into community resources that offer comfort and guidance. Consider joining in-person or online support groups, where you can talk with others who understand.

A note from Cleveland Clinic

It can be stressful to have a genetic condition that raises your risk of cancer. But you’re not alone. Your healthcare team is here to help you take charge of your health. Today’s advanced cancer screenings can greatly reduce your risk of getting cancer or find it early. And if you encounter emotional or mental health concerns, your provider can help you get the treatment and support you need.