Ataxia Telangiectasia
Ataxia Telangiectasia
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Authors: Praveen Kumar Ramani, MBBS, University of Arkansas/Arkansas Children’s Hospital, Geetanjali Rathore, MD, Children’s Hospital and Medical Center, Omaha, NE 


Reviewed: December 2022 


Ataxia telangiectasia (AT) is a genetic disorder. It is rare and inherited. It affects:  

  • The brain  
  • The immune system 

Patients can have an increased risk of: 

  • Infection 
  • Cancer  

AT is often diagnosed between the ages of one and four. In the United States, it affects one in 40,000 to 100,000 live births. It affects both sexes equally. Race is not a factor.   

AT is an autosomal recessive disease. This means a patient inherits two nonfunctioning copies of a gene. They get one from each parent.  

The main signs of AT are:

A lack of coordination (progressive ataxia).

This results from cerebellar degeneration. (The cerebellum is a small portion of the brain. It is located at the back of the head.) 

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Arm and leg movements (choreoathetosis).

These are involuntary and jerky.

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Dilated blood vessels (telangiectasia).

These can appear on:  

  • The eyes  
  • The skin 
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Recurrent infections.

This results from a weakened immune system.  

  • Patients are sensitive to radiation.  
  • They also have an increased risk of certain cancers. These include:  
    • Leukemia  
    • Lymphoma 
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Diagnosis is often made after:  

  • A complete medical history  
  • Lab tests  

This includes tests for immune deficiency. To confirm the diagnosis, these tests are done:

  • Genetic testing. This looks for a mutation or change in the gene structure. 
  • Magnetic resonance imaging (MRI). Images of the brain are taken.  

Treatment is often supportive. It aims to: 

  • Prevent complications  
  • Manage complications 


Disorder Overview


AT is a rare genetic condition. It affects: 

  • The nervous system  
  • The immune system 

It also predisposes the patient to cancer.  

The child is usually normal at birth. Symptoms often manifest between one and three. The child usually has trouble with: 

  • Walking  
  • Coordination 

The condition is associated with a small cluster of dilated blood vessels. These appear on:  

  • The eyes  
  • The skin 

AT typically worsens over time. Treatment is often supportive.  

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Most patients with AT are diagnosed in late infancy to early childhood. AT is one of the most common inherited causes of early childhood-onset ataxia.  

Symptoms vary. Common and serious symptoms include:

Neurological symptoms.

Nervous system complications are very common. These include: 

  • Ataxia (unstable walk). Growth and development appear normal at birth. Ataxia is typically noted when the child starts walking. They wobble or sway. This can also occur when:  
    • Standing 
    • Sitting  

Ataxia typically worsens. By the second decade of life, walking is almost impossible. Patients often need a wheelchair. 

  • Oculomotor apraxia (difficulty moving eyes). A patient can have trouble moving their eyes from side to side at the same time. This is the distinguishing feature of AT.  Patients often have compensatory mechanisms. These are things they do to make up for this difficulty. Examples include: 
    • Eye blinking  
    • Head thrusting 
  • Choreoathetosis. This refers to writhing movements. They are involuntary. They involve: 
    • The face 
    • The arms 
    • The legs 

This occurs in up to 90% of patients. Movements become more noticeable with age.  

  • Facial weakness. A patient’s face does not express emotion.   
  • Slurred speech and drooling. These can worsen over time.  
  • Muscle weakness. This can also worsen over time. It affects: 
    • The hands  
    • The feet  

By the late second to the third decade of life, weakness may develop.   

  • Short-term memory issues. This can occur in the third to fourth decade of life. However, cognition is usually well preserved.  
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Skin and eye symptoms.

  • Telangiectasia (dilated, corkscrew-shaped blood vessels). This can appear on: 
    • The whites of the eyes  
    • Sun-exposed areas of skin 

It is typically observed in patients between the ages of two and four.  

  • Premature aging of skin and hair 
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Sinus and lung infections.

These can be recurrent.

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Increased risk of cancer.

The patient can be at risk of developing: 

  • Leukemia 
  • Lymphoma  
  • Brain tumors 
  • Stomach cancer 
  • Ovarian cancer 
  • Uterine cancer  
  • Breast cancer  
  • Skin cancer 
  • Other cancers 
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Sensitivity to ionizing radiation.

This includes: 

  • X-rays 
  • CT scans 
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Endocrine abnormalities.

These include: 

  • Short stature 
  • Type II diabetes  
  • Delayed puberty 
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Humans have 46 chromosomes. These include: 

  • 22 pairs of somatic chromosomes  
  • One pair of sex chromosomes  

AT is caused by mutations in a gene. The gene is called ATM (ataxia-telangiectasia mutated). ATM is on chromosome 11. It is located at an area called q22.3. 

The ATM gene has several functions. These include: 

Controlling cell division.

It prevents cells from: 

  • Growing too quickly 
  • Dividing too quickly

It acts as a tumor suppressor.

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Repairing DNA.

The gene works with other proteins. It can help repair DNA in certain situations. For example, it can help with exposure to ionizing radiation.

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AT is an autosomal recessive disorder. This means both parents must pass the abnormal gene to the child. That is how a child develops this condition.  

Patients with only one ATM mutation are considered carriers. They don’t have symptoms. Approximately 1% of people in the United States are carriers. 

Patients with AT have a defective ATM gene. This affects all cells of their body. Altered genes make abnormal or reduced protein. This results in:  

  • Defective DNA repair  
  • Abnormal cell division 

These can then develop: 

  • Brain dysfunction  
  • Cancer 


Several tests can help to diagnose HH and problems related to HH. These tests include:

AT is often diagnosed in early childhood. These help with diagnosis: 

  • A complete medical history 
  • A detailed family history. This will identify:  
    • Family members who have cancer 
    • The type of cancer 
    • Their age of onset 
  • A physical exam 

If AT is suspected, blood work will be ordered. This will include: 

  • Basic lab tests  
  • Specific tests (such as genetic testing) 

Labs may include: 

Serum alpha-fetoprotein (AFP) concentration.

AFP is a protein made by a developing baby. 

  • More than 90% of AT patients have increased AFP. Their AFP is increased more than 10 nanograms per milliliter.  
  • AFP labs need to be interpreted carefully. Serum AFP can remain elevated in children up to two years old. 
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Carcinoembryonic antigen (CEA).

CEA is a blood protein. Children with AT have increased CEA levels.

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Immunoglobulin levels (Ig).

Immunoglobulins are antibodies. In AT patients: 

  • IgA and IgE are often decreased or missing.  
  • IgM, IgG1, and IgG3 are normal or increased.  
  • IgG2 and IgG4 are generally decreased.  
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Genetic testing

  • Specific genetic testing can examine chromosome 11q22.3. Tests can look for a deletion or missense mutation.  
  • Diagnosis is often clinical. However, genetic testing for ATM mutation is recommended. It can identify whether a patient is a carrier. Carriers are at risk of developing cancer.  
  • Genetic testing can also help with decisions about prenatal genetic testing. 
  • Special tests measure the level of ATM protein in cells. In patients with AT, 10% do not have a detectable alteration. So, failure to identify alterations should be carefully interpreted. This is especially true if AT is suspected.
  • A translocation is when chromosomes are rearranged. In patients with AT, a 7:14 chromosomal translocation is common. This occurs in 5 to 15% of cells. 
  • Genetic testing of family members is often recommended. This can identify whether they are carriers. 
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Radiosensitive assay.

This test measures DNA repair function. Cells are exposed to radiation. Cells from AT patients do not survive radiation.

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Magnetic resonance imaging (MRI).

Images can be taken of the brain. They often show shrinkage (atrophy) of the cerebellum. MRI can also rule out other structural lesions of the brain. These can cause: 

  • Unstable gait  
  • Lack of coordination 
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Your doctor will perform additional tests to look for complications. These include:

A complete blood count with differentials.

This looks at white blood cells. It looks at the number of each kind. It can screen for:  

  • Leukemia  
  • Lymphoma 
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A complete metabolic panel and hemoglobin A1C.

This screens for diabetes. 

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Periodic medical visits.

These can monitor for early signs of: 

  • Leukemia  
  • Lymphoma

Such signs include: 

  • Weight loss 
  • Excessive fatigue 
  • Bruising 
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Speech evaluation.

This can assess the need for speech therapy.

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Swallow evaluation.

This can lower the risk of aspiration. (Aspiration is when something enters the airway.)

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A nutrition and feeding assessment.

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Prenatal testing 

Parents can undergo genetic testing before or during pregnancy.  

Parents should consider talking to a genetic counselor. They can review the advantages and disadvantages of testing. They can also help parents better understand results.  

There are two types of prenatal testing. They are:

Before pregnancy.

This test is called preimplantation genetic testing (PGT). It is done in cases of in vitro fertilization. The embryo is tested for known ATM mutations. Only healthy embryos are implanted.

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During pregnancy.

A test called chorionic villus sampling is done. This occurs during the first three months. In the next six months, a test called amniocentesis is done.  

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AT worsens over time. It affects multiple systems. There is no cure.  

Care from a variety of doctors is usually needed. Based on the symptoms, your doctor will coordinate with the appropriate specialists. This often includes: 

  • A neurologist 
  • An oncologist 
  • An immunologist 
  • Physical medicine and rehabilitation 
  • Physical therapy 
  • Occupational therapy  
  • Speech therapy 

Neurologic problems are often treated symptomatically. Early, continued therapy is important. 

Antibiotics can treat infections. Some patients have low immunoglobulin levels. For them, IVIG replacement therapy should be considered. 

Special care is needed when treating cancer in patients with AT. They are more sensitive to:  

  • Ionizing radiation  
  • Chemotherapy 

Neoplasm should be treated with extreme caution.  

Prevention of secondary complications 

A patient may have trouble swallowing. If so, a feeding tube may be needed. This allows them to receive nutrition.  

Children with AT and carriers are very sensitive to radiation. They have a higher risk of cancer. Certain medical tests should be avoided when possible. These tests include:  

  • X-rays 
  • CT scans  
  • Mammograms  

Parents should notify their doctor immediately if they notice:  

  • Weight loss 
  • Localized swelling or bruising 
Perinatal Stroke 3


Life expectancy depends on:  

  • The genetic alteration  
  • Symptom severity 

Most patients live into early adulthood. These can prolong life expectancy: 

  • Early diagnosis  
  • Early treatment of infection and cancer 

Related disorders include: 


National Ataxia Foundation 
The National Ataxia Foundation’s vision of a world without Ataxia will be accomplished through its primary programs of funding Ataxia research, providing vital programs and services for Ataxia families, and partnering with pharmaceutical companies in the search for treatments and a cure. NAF offers many educational resources for Ataxia, including a comprehensive library of brochures, fact sheets, and books. NAF oversees the Parents of Kids with Ataxia private Facebook group, which currently has over 800 members.

Ataxia Telangiectasia Children’s Project 
The Ataxia Telangiectasia Children’s Project (A-T Children’s Project) partners with academic and industry investigators worldwide – organizing and supporting innovative research, conferences, clinical teams, data platforms and biomarkers – to optimize disease management strategies, develop new treatments, and find a cure for ataxia-telangiectasia. A-T parents host A-T Parents Rock!!!, a private Facebook support group for caregivers of people with A-T.  

Ataxia-Telangiectasia Society  
The Ataxia-Telangiectasia Society (A-T Society) supports people living with the disabling and life-limiting condition ataxia-telangiectasia and funds research to find a cure. A-T Society serves families in the UK. They provide: a support team, guidance for local specialist clinics, grants, and a chance to meet others families. A-T Society’s publications and films are accessible online and may be relevant for families in other countries. 

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Child Neurology Foundation (CNF) solicits resources from the community to be included on this webpage through an application process. CNF reserves the right to remove entities at any time if information is deemed inappropriate or inconsistent with the mission, vision, and values of CNF. 

Research for Ataxia Telangiectasia (birth to 17 years).

These are clinical trials that are recruiting or will be recruiting. Updates are made daily, so you are encouraged to check back frequently. is a database of privately and publicly funded clinical studies conducted around the world. This is a resource provided by the U.S. National Library of Medicine (NLM), which is an institute within the National Institutes of Health (NIH). Listing a study does not mean it has been evaluated by the U.S. Federal Government. Please read the NLM disclaimer for details.    

Before participating in a study, you are encouraged to talk to your health care provider and learn about the risks and potential benefits.

Family Stories 

The National Ataxia Foundation (NAF) shares stories of adults and children living with Ataxia on their Member Stories page.

The information in the CNF Child Neurology Disorder Directory is not intended to provide diagnosis, treatment, or medical advice and should not be considered a substitute for advice from a healthcare professional. Content provided is for informational purposes only.  CNF is not responsible for actions taken based on the information included on this webpage. Please consult with a physician or other healthcare professional regarding any medical or health related diagnosis or treatment options. 


Gatti R, Perlman S. Ataxia-Telangiectasia. 1999 Mar 19 [Updated 2016 Oct 27]. In: Adam MP, Everman DB, Mirzaa GM, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2022. Available from: 

Rothblum-Oviatt C, Wright J, Lefton-Greif MA, McGrath-Morrow SA, Crawford TO, Lederman HM. Ataxia telangiectasia: a review. Orphanet J Rare Dis. 2016 Nov 25;11(1):159. PMID: 27884168; PMCID: PMC5123280. 

Amirifar P, Ranjouri MR, Lavin M, Abolhassani H, Yazdani R, Aghamohammadi A. Ataxia-telangiectasia: epidemiology, pathogenesis, clinical phenotype, diagnosis, prognosis and management. Expert Rev Clin Immunol. 2020 Sep;16(9):859-871. Epub 2020 Oct 15. PMID: 32791865. 

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