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  • Updated 01.22.2024
  • Released 07.12.1994
  • Expires For CME 01.22.2027




Ataxia-telangiectasia is an autosomal recessive condition of genomic instability that clinically presents in childhood as progressive ataxia and incoordination, dilated blood vessels of skin and conjunctiva, frequent sinus and pulmonary infections due to immune deficiencies, and an increased risk of certain malignancies. Elevated serum alpha-fetoprotein is seen in over 90% of patients; molecular testing of the ataxia telangiectasia mutated (ATM) gene is clinically available. Measurement of serum IgA may predict lower lymphocyte counts and reduced survival prognosis.

Key points

• Ataxia-telangiectasia is an autosomal recessive condition characterized by progressive childhood ataxia, oculomotor apraxia, some degree of immunodeficiency, an increased risk for certain malignancies, and telangiectasias of the skin and conjunctiva.

• Elevated serum alpha-fetoprotein is an important biochemical marker because the hallmark telangiectasias do not appear until later in the clinical course.

• The principal defect is in the ataxia-telangiectasia mutated (ATM) gene, whose end product is a protein kinase involved in cell cycle regulation.

• Patients are at an increased risk for certain malignancies, primarily leukemias and lymphomas, and are hypersensitive to ionizing radiation.

• Patients with variant ataxia-telangiectasia may present initially with extrapyramidal movement disorders but are also at an increased risk for malignancy and hypersensitivity to ionizing radiation.

Historical note and terminology

In 1926, Syllaba and Henner first described the association of oculocutaneous telangiectasias with choreoathetosis. Louis-Bar reported the combination of oculocutaneous telangiectasias with progressive cerebellar ataxia in 1941. In 1958, Boder and Sedgwick studied eight cases from five unrelated families, including six familial cases. They emphasized the heredofamilial nature of the disease and the susceptibility of these patients to sinopulmonary infections. They named this syndrome ataxia-telangiectasia (07). Ataxia-telangiectasia is now recognized as one of a group of recessive hereditary genomic instability disorders and is characterized by progressive neurodegeneration, immunodeficiency, and cancer susceptibility.

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