Ataxia-telangiectasia (A-T)

Ataxia-telangiectasia (A-T) is a rare hereditary condition that affects the nervous system, immune system, and other body systems. Other names for A-T include Louis-Bar syndrome, cerebello-oculocutaneous telangiectasia, and immunodeficiency with ataxia telangiectasia.  

What are the effects of ataxia-telangiectasia (A-T)?

People with A-T have trouble with movement and an increased risk of some types of cancer (see below).

Children with A-T may begin staggering and appear unsteady (called ataxia) shortly after learning to walk. Most people with A-T  eventually will need to use a wheelchair. Over time, people with A-T tend to develop slurred speech and have trouble with writing and other tasks.

Red marks called telangiectasias are caused by dilated capillaries and may appear on the skin and eyes as people get older.

People with A-T also have weakened immune systems, are prone to infections, and appear to be particularly sensitive to ionizing radiation, such as x-rays.

How common is ataxia-telangiectasia (A-T)?

A-T is rare. It affects about 1 out of every 40,000 to 100,000 people. The chance that a person is a carrier of a single ATM gene mutation is about 1%, or 1 in 100.

What causes ataxia-telangiectasia (A-T)?

Changes (mutations) in the ATM gene on chromosome 11 cause A-T.

Both parents must have and pass on the mutated ATM gene for their child to have the condition. People with only one ATM mutation gene are carriers of the disease, but they do not have any symptoms.

Options exist for people who carry an ATM gene mutation and might want to have children. For more information, talk with an assisted reproduction specialist at a fertility clinic.

How is ataxia-telangiectasia (A-T) diagnosed?

A-T is initially suspected when a child develops signs of ataxia, meaning unsteady walking. To confirm if the child has A-T, imaging and blood tests are done, such as:

• Genetic testing: This is a blood test to see if the child has a mutation in both of their ATM genes.
• MRI (magnetic resonance imaging) of the brain: People with A-T often have abnormal findings on a brain MRI.
• Other blood tests: People with A-T tend to have high levels of alpha-fetoprotein (AFP) in their blood.

What types of cancer are linked with ataxia-telangiectasia (A-T)?

People with A-T have an increased risk of developing some types of cancer. The most common types of cancer seen in people with A-T are leukemia and lymphoma. These cancers can appear in childhood, and account for most of the cancers in people with A-T. As people with A-T live longer, there appears to be an increased risk of other cancer types, including breast cancer, ovarian cancer, stomach cancer, melanoma, and sarcoma.

What are the cancer risks for people who carry an ATM gene mutation?

People with one ATM gene mutation (carriers) also have an increased risk of developing breast cancer. Studies have shown that carriers have about twice the lifetime risk of developing female breast cancer compared to the general population. We do not yet know whether there is an increased risk of male breast cancer among ATM carriers.

Some data suggests that ATM mutation carriers may also have an increased risk for ovarian, pancreas, skin and prostate cancers, but this isn’t entirely clear.

More research is needed to clarify the risk of cancer and other conditions among ATM mutation carriers.

How often should people with ataxia-telangiectasia (A-T) (or an ATM gene mutation) be screened for cancer?

Cancer screening for people with A-T

Children and adults with A-T should see their doctor regularly and be monitored for signs of cancer. People with A-T who have frequent infections are encouraged to have their immune status checked regularly.

Cancer screening for ATM gene mutation carriers

Females with only 1 ATM gene mutation (carriers) also have an increased risk of developing breast cancer. Because of this, the National Comprehensive Cancer Network (NCCN) recommends that these women have yearly breast cancer screening with a mammogram and possibly a breast MRI, often starting at an earlier age than normal.

Screening options may change over time as new technologies are developed and more is learned about A-T. It is important to talk with your health care team about which screening tests to have and when to have them.

Questions to ask the health care team

If you are concerned about your (or your child’s) cancer risk, talk with the health care team. It can be helpful to bring someone along to your appointments to take notes.

Consider asking the following questions:

• What is my (child’s) risk of developing different types of cancer?
• What can I/we do to lower the risk of developing cancer?
• What cancer screening tests should be done?

If you are concerned about your family history and think your family may carry an ATM gene mutation, consider asking the following questions:

• Could my family carry the gene mutation for A-T?
• Does my family history increase my risk of developing cancer?
• Should I speak with a genetic counselor or other genetics specialist? Can you refer me to someone?
• Should I consider genetic testing?