Ataxia-Telangiectasia (A-T)

Telangiectasia — Beginning at the age of 5 or 6 years, most patients show another clinical hallmark of A-T, telangiectasia. These appear as a tiny tangle of veins, in the whites of the eyes, making them seem bloodshot, or like "pink eye" without pus. "telangiectasia" may also appear on the surface of the ears, on the cheeks, and other areas of skin that are exposed to sunlight. Although they are harmless, their unique appearance together with ataxia is what led to naming this disease "ataxia-telangiectasia."

Approximately 80% of the children with A-T have some degree of immunodeficiency that may predispose them to develop recurrent respiratory infections. The most common problem is a deficiency of immunoglobulins or antibodies, the natural infection fighting agents in the blood. The combination of a weakened immune system and problems with chewing and swallowing can lead to pneumonia as a cause of death.

Children with A-T develop malignancies of the blood system such as leukemia and lymphoma almost 1000 times more frequently than the general population. The risk of developing other types of cancer may also be elevated, but to a less dramatic degree. Patients with A-T are also extremely sensitive to radiation, which means that they cannot tolerate the therapeutic radiation usually given to cancer patients.

Other conditions that may affect children with A-T include:

• Diabetes mellitus
  
• Premature graying of the hair
  
• Delayed or incomplete puberty
  
• Slowed growth
  

The physical exam may include tests for wobbly gait, swaying of the head and trunk, tremor, abnormal eye movements, slurred speech, and difficulty chewing or swallowing.

Laboratory tests check for: elevated serum alpha-fetoprotein levels after one year of age; chromosome damage and reduced survival of lymphocyte and/or fibroblast cultures following exposure to x-rays ; spontaneous chromosome breaks and rearrangements in cultured lymphoblasts or fibroblasts; and low serum levels of immunoglobulins (IgA, IgG, IgE, IgG subclasses). Specific tests of the A-T gene or its protein product, ATM may also be perfomed. Western blot analysis and enzyme activity assays are used to monitor the presence and function of the A-T protein.

DNA tests are used to confirm the diagnosis in atypical cases. DNA tests can also be performed to identify specific mutations in the A-T gene, to make the diagnosis in a fetus or very young child, and to identify family members who are carriers for the A-T gene.

A-T is presently incurable. Most A-T children depend on a wheelchair by the age of 10 because they cannot control their balance well enough to walk long distances. Children with A-T usually die from respiratory failure or cancer by their teens or early twenties, but some patients have lived decades longer.

There is no way as yet to slow the progression of the disease. Treatments now are directed towards partly alleviating some symptoms as they appear. Physical, occupational, and speech therapy are used to help maintain flexibility and the highest degree of functioning possible. Gamma-globulin infusions are used to supplement the immune systems of A-T patients who lack immunoglobulins or antibodies. Alterations in feeding, sometimes involving the use of gastrostomy tubes, can be used to prevent aspiration (swallowed food and liquids getting into the lungs instead of the stomach) and to maintain adequate nutrition.

For more information, visit the A-T Children's Project Website.