Ataxia-telangiectasia (A-T) is a rare genetic condition that affects the function of the nervous system, the immune system and several other body systems. Defining symptoms of A-T are zig-zag blood vessels on the skin and difficulty with coordination and movement. There is no cure for A-T but treatment addresses the symptoms.


Ataxia-telangiectasia symptoms that affect both your nervous system and immune systems.
Ataxia-telangiectasia targets your nervous and immune systems, causing symptoms throughout your body.

What is ataxia-telangiectasia?

Ataxia-telangiectasia (A-T), also known as Louis-Bar Syndrome, is a rare genetic condition that targets the nervous system, immune system and other systems throughout your body. The condition is neurodegenerative when cells in your body’s central nervous system progressively stop working. People diagnosed with A-T most commonly have trouble with movement and coordination (ataxia), which begins in early childhood. A notable characteristic of the condition is small clusters of dilated blood vessels that appear in the eyes and on the skin (telangiectasia).


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Who does ataxia-telangiectasia affect?

A genetic mutation causes ataxia-telangiectasia. Anyone can inherit ataxia-telangiectasia if their parents both carry a copy of the ATM gene mutation and pass that onto their child (autosomal recessive). Parents can both carry one copy of the gene but will not show symptoms of the condition because they need two copies of the gene to receive an ataxia-telangiectasia diagnosis. An estimated 1% of people in the U.S. carry a mutated copy of the ATM gene.

How common is ataxia-telangiectasia?

Ataxia-telangiectasia is rare and occurs in an estimated 1 out of every 40,000 to 100,000 people worldwide.


How does ataxia-telangiectasia affect my child’s body?

Ataxia-telangiectasia is a degenerative condition, which progressively gets more severe over time. Children diagnosed with A-T will show signs of the condition as early as age 5. Children's symptoms focus on their movements like being off-balance when they walk, jerking their arms and legs, twitching their muscles and slurring their speech. When your child reaches adolescence, they will most likely need mobility assistance, like a wheelchair, to navigate the world.

Symptoms and Causes

What are the symptoms of ataxia-telangiectasia?

Two defining characteristics of ataxia-telangiectasia are difficulty with coordination (ataxia) and small zig-zag clusters of blood vessels forming in the eyes and on the skin (telangiectasia). Other symptoms of A-T affect movement including:

  • Difficulty walking.
  • Inability to move eyes side-to-side (oculomotor apraxia) or other eye jumping (nystagmus) movements.
  • Involuntary jerking movements (chorea).
  • Muscle twitching (myoclonus).
  • Nerve function declining (neuropathy).
  • Slurred speech. (Most children never obtain “normal” speech due to problems articulating and inappropriate emphasis on the wrong syllables or parts of words).
  • Trouble with balance.
  • Poor growth or endocrine dysfunction (made worse by frequent infections and growth hormone changes).

Ataxia-telangiectasia affects the function of a person’s immune system, weakening it as the condition develops over time. Symptoms of a weakened immune system in people diagnosed with A-T include:

  • Chronic lung infections.
  • Fatigue.
  • Feeling sick more often.
  • Frequent infections and delayed wound healing.
  • Leukemia.
  • Lymphoma.
  • Sensitivity to radiation exposure (X-rays).

Another symptom of A-T is high levels of alpha-fetoprotein (AFP), which is a protein in the blood. The cause of increased AFP levels is unknown.


What causes ataxia-telangiectasia?

A mutation of the ATM gene causes ataxia-telangiectasia.

Most people have 46 chromosomes that divide into 23 pairs of two. Chromosomes carry DNA in the nucleus of cells. DNA is the instruction manual that tells your body how to form and function. Genes are segments of your DNA that contain chapters in your body’s instruction manual. Each chromosome contains several genes.

You receive one chromosome from each of your parents to form a pair. When cells form in reproductive organs, the cells divide and copy themselves. During cell division, genetic mutations occur at random, similar to how a printer would get a paper jam. Some copies of your instruction manual are exactly how they should be and others print askew (genetic mutation).

The mutated gene moves in an autosomal recessive pattern during fertilization when both parents pass a mutated gene onto their child. If only one parent passes the gene, the child will be a carrier of the genetic condition but they will not show symptoms of A-T. Two copies of the mutated gene are necessary for an A-T diagnosis.

The ATM gene is responsible for creating proteins that tell your body how to repair broken strands of DNA. ATM proteins locate damaged cells and DNA strands and recruit enzymes to fix them. The repairing process of DNA helps the pages in your body’s instruction manual turn smoothly.

ATM proteins also tell your body systems to stay active, especially the nervous and immune systems, so they can do their assigned jobs.

A mutation of the ATM gene reduces the function of the ATM protein over time. This means that cells lose pieces of their instruction manual and are unable to complete their function, which ultimately causes symptoms of ataxia-telangiectasia.

Diagnosis and Tests

How is ataxia-telangiectasia diagnosed?

Diagnosis of ataxia-telangiectasia begins with a physical examination of symptoms, followed by imaging and blood tests to verify the genetic mutation responsible for symptoms. Your healthcare provider will also gather more information about your child’s health and family history through a detailed medical evaluation before confirming the diagnosis. People with suspected A-T should see an immunologist for a complete workup and evaluation.

What tests diagnose ataxia-telangiectasia?

Tests that help diagnose ataxia-telangiectasia include:

  • Genetic testing: Genetic testing is a blood test that pinpoints the exact gene mutation responsible for causing symptoms.
  • Magnetic resonance imaging (MRI): An MRI will take images of the brain to look for weakened neurons or cerebellar cells (cerebellar atrophy), which is a sign of progressive ataxia.
  • Karyotyping: A blood test examines chromosomes for genetic conditions.
  • Blood tests: Blood tests will look for increased levels of the alpha-fetoprotein.

Many states offer newborn screenings that can diagnose ataxia-telangiectasia at birth. Otherwise, healthcare providers usually diagnose the condition in early childhood.

Management and Treatment

How is ataxia-telangiectasia treated?

Treatment for ataxia-telangiectasia addresses symptoms of the condition. There is no cure for A-T. Treatment is unique for each person diagnosed with the condition and could include:

  • Avoiding overexposure to sunlight to control dilated blood vessels (telangiectasia).
  • Chemotherapy treatment for cancer.
  • Physical therapy to strengthen muscles.
  • Receiving gammaglobulin injections for respiratory infections.
  • Receiving immunoglobulin therapy to address a weakened immune system.
  • Taking antibiotics to treat infections.
  • Taking diazepam to control slurred speech and involuntary muscle movements.


How can I reduce my risk of having a child diagnosed with ataxia-telangiectasia?

Since ataxia-telangiectasia is the result of a genetic mutation, there is no way to prevent it from occurring. You can take steps to reduce your risk of having a child with a genetic condition by avoiding smoking and avoiding exposure to chemicals. If you plan on becoming pregnant, talk with your healthcare provider about genetic testing to understand your risk of having a child with a genetic condition like ataxia-telangiectasia.

Outlook / Prognosis

What can I expect if I have a child diagnosed with ataxia-telangiectasia?

Ataxia-telangiectasia is a degenerative condition that gets worse as the condition progresses over time. Mild symptoms affecting your child’s movement will arise during childhood, along with visible blood vessel clusters on the skin. As your child ages, their cells lose the ability to function as their instruction manual indicates. This means that your child’s symptoms will increase in severity and they will likely need to use a wheelchair to help them become more mobile by early adolescence.

A symptom of the condition is a weakened immune system, which can make small infections detrimental to your child’s health. Their weakened immune system also makes people diagnosed with the condition more susceptible to cancer like leukemia or lymphoma. Treatment is available to improve immune system function so your child can stay healthy.

Life expectancy varies based on the severity of the symptoms of A-T, but most people diagnosed with the condition live into early adulthood (up to 30 years of age, with the median age being around 25 years). Early treatment for recurrent infections and preventative screenings can help prolong life expectancy.

Is there a cure for ataxia-telangiectasia?

There is no cure for ataxia-telangiectasia. Treatment helps alleviate symptoms and prolong the life and comfort of each person diagnosed with the condition.

Living With

How do I take care of my child diagnosed with ataxia-telangiectasia?

After your child receives an ataxia-telangiectasia diagnosis, it may be difficult to understand the full scope of their condition and to know exactly how to help them. Your child’s healthcare provider will recommend treatment that is unique for their symptoms and be available to answer any questions you might have.

Your healthcare provider might suggest talking with a genetic counselor who is an expert in genetics and can help your family learn more about ataxia-telangiectasia and ways that you can help your child live a comfortable and fulfilling life. A genetic counselor can also provide emotional support as you navigate your child’s diagnosis.

When should I see my healthcare provider?

Since ataxia-telangiectasia affects the immune system, if you notice your child shows signs of an infection, you should visit your healthcare provider to receive treatment. Signs of an infection include:

  • Change in skin color of the affected area.
  • Chills.
  • Coughing.
  • Fever.
  • Pain or sore feeling in an area of the body or throughout.
  • Raised skin around an area of the body (swelling).
  • Shortness of breath.
  • Vomiting or diarrhea.

What questions should I ask my doctor?

  • Does my child need to see a physical therapist to improve their muscle strength?
  • Are there any side effects to the treatment you prescribed to address my child’s symptoms?
  • Am I at risk of having a child diagnosed with ataxia-telangiectasia if I carry the mutated gene?

A note from Cleveland Clinic

Understanding your child’s ataxia-telangiectasia diagnosis can be overwhelming as their caregiver. Your healthcare provider will offer a robust treatment plan that is unique to your child’s symptoms. It is important to provide your child with the love and support they need throughout their life and stay regular and attentive to their health to address any new symptoms that arise to prolong their life expectancy.

Medically Reviewed

Last reviewed on 07/06/2022.

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