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Gatti R1, Perlman S2.


GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2018.
1999 Mar 19 [updated 2016 Oct 27].

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Departments of Pathology and Human Genetics, David Geffen School of Medicine at UCLA, Los Angeles, California
Department of Neurology, David Geffen School of Medicine, UCLA Health System, Los Angeles, California



Classic ataxia-telangiectasia (A-T) is characterized by progressive cerebellar ataxia beginning between ages one and four years, oculomotor apraxia, choreoathetosis, telangiectasias of the conjunctivae, immunodeficiency, frequent infections, and an increased risk for malignancy, particularly leukemia and lymphoma. Individuals with A-T are unusually sensitive to ionizing radiation. Non-classic forms of A-T have included adult-onset A-T and A-T with early-onset dystonia.


The diagnosis of A-T is suspected based on suggestive clinical and preliminary laboratory findings and – in some instances – neuroimaging and family history. The diagnosis is established in a proband either by molecular genetic testing to document the presence of biallelic (homozygous or compound heterozygous) ATM pathogenic variants or (when available) by immunoblotting to test for absent or reduced ATM protein.


Treatment of manifestations: Neurologic: supportive therapy and medications (when possible) as well as early and continued physical therapy to reduce the risk for contractures and scoliosis. Immunodeficiency: IVIG replacement therapy as needed for (a) frequent and severe infections and (b) low IgG levels. Pulmonary: multidisciplinary management that emphasizes monitoring of recurrent infection, pulmonary function, swallowing, nutrition, scoliosis, and immune function. Cancer: because of the increased sensitivity of A-T cells, use of ionizing radiation and some chemotherapeutic agents requires careful monitoring. Prevention of secondary complications: Gastrostomy tube feedings are occasionally needed to prevent pulmonary and nutritional complications of dysphagia. Attention to potential risks of anesthesia including impaired swallowing, increased risk of aspiration, reduced pulmonary function, and infection. Surveillance: In those with severe recurrent infections or undergoing immunomodulatory therapy: monitoring of pulmonary function and other signs of pulmonary disease and early signs of malignancy (e.g., weight loss, bruising, localized pain or swelling).


A-T is inherited in an autosomal recessive manner. At conception, the sibs of an affected individual have a 25% chance of being affected, a 50% chance of being asymptomatic carriers, and a 25% chance of being unaffected and not carriers. ATM heterozygotes (carriers) are at increased risk of developing cancer. Once the ATM pathogenic variants have been identified in an affected family member, carrier testing for at-risk relatives, prenatal testing of pregnancies at increased risk, and preimplantation genetic diagnosis are possible.

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