Ataxia-telangiectasia is a hereditary disorder characterized by incoordination, dilated capillaries, and increased susceptibility to infections.

The increased susceptibility to infections in people with ataxia-telangiectasia results from malfunction of B 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. Sinus and respiratory infections recur, often leading to pneumonia and chronic lung disorders such as bronchitis. The risk of cancer, especially leukemia, brain tumors, and stomach cancer, is increased.

This disorder also causes abnormalities in the cerebellum (the part of the brain that coordinates the body's movements), which are unrelated to the immunodeficiency disorder. Incoordination (ataxia) results, usually when children begin to walk, but it may be delayed until age 4. Speech becomes slurred, and muscles progressively weaken, leading to severe disability. Mental retardation may develop and progress. Between the ages of 1 and 6, capillaries in the skin and eyes become dilated and visible. The dilated capillaries (telangiectasia), called spider veins, are usually most obvious on the eyeballs and ears. The endocrine system may be affected, resulting in small testes (in boys), infertility, and diabetes.

Doctors suspect the diagnosis based on symptoms. Blood tests to measure the levels of IgA and genetic tests can help confirm the diagnosis.

Antibiotics and immune globulin (to provide the missing immunoglobulins) help prevent infections but do not relieve the other problems. Ataxia-telangiectasia usually progresses to paralysis, dementia, and death, typically by age 30.

Last full review/revision September 2008 by Rebecca H. Buckley, MD