Merck Manual

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James Fernandez

, MD, PhD, Cleveland Clinic Lerner College of Medicine at Case Western Reserve University

Last full review/revision Dec 2019| Content last modified Dec 2019
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Ataxia-telangiectasia is a hereditary disorder characterized by incoordination, dilated capillaries, and an immunodeficiency that causes increased susceptibility to infections.

  • In children with ataxia-telangiectasia, incoordination usually develops when they begin to walk, and muscles progressively weaken, causing them to be greatly disabled.

  • Doctors do blood tests to diagnose the disorder.

  • Treatment involves antibiotics (to prevent infections) and immune globulin.

Ataxia-telangiectasia is a primary immunodeficiency disorder. It is usually inherited as an autosomal (not sex-linked) recessive disorder. That is, two genes for the disorder, one from each parent, are required.

The increased susceptibility to infections in people with ataxia-telangiectasia results from malfunction of B cells and T cells (lymphocytes), which help the body defend itself against microorganisms and abnormal cells. Often, levels of certain types (classes) of antibodies (immunoglobulins)—IgA and IgE—are also low.

Ataxia-telangiectasia also causes abnormalities in the cerebellum (the part of the brain that coordinates the body’s movements), which are unrelated to the immunodeficiency disorder and which result in loss of coordination.


Incoordination (ataxia) usually develops when children begin to walk, but it may be delayed until age 4. Speech becomes slurred, and muscles progressively weaken, leading to severe disability. Intellectual disability may develop and progress.

Between the ages of 1 and 6 (but often not until age 4), capillaries in the skin and eyes become dilated and visible. The dilated capillaries (telangiectasia), called spider veins, are usually most obvious on the eyeballs, ears, and sides of the neck.

The endocrine system may be affected, resulting in small testes (in boys), infertility, and diabetes.

Sinus and lung infections recur, often leading to pneumonia and chronic lung disorders such as bronchiectasis (irreversible widening due to chronic inflammation of the airways).

The risk of cancer, especially leukemia, lymphoma, brain tumors, and stomach cancer, is increased.

Ataxia-telangiectasia usually progresses to paralysis, dementia, and death, typically by age 30.


  • Blood tests

  • Genetic testing

Doctors suspect ataxia-telangiectasia based on symptoms.

Blood tests to measure the levels of IgA and genetic tests can help confirm the diagnosis.

If doctors suspect endocrine disorders or cancers based on results of their examination, tests to check for these disorders are done.


  • Antibiotics and immune globulin

To help prevent infections, doctors give people antibiotics and immune globulin (antibodies obtained from the blood of people with a normal immune system), which provides the missing immunoglobulins. Immune globulin may be injected into a vein (intravenously) once a month or under the skin (subcutaneously) once a week or once a month.

However, these drugs do not relieve the other problems.

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Drugs Mentioned In This Article

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Gammagard S/D
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