(See also Overview of Immunodeficiency Disorders Overview of Immunodeficiency Disorders Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more and Approach to the Patient With an Immunodeficiency Disorder Approach to the Patient With Suspected Immunodeficiency Immunodeficiency typically manifests as recurrent infections. However, recurrent infections are more likely to have causes other than immunodeficiency (eg, inadequate treatment, resistant organisms... read more .)
Ataxia-telangiectasia is an autosomal-recessive primary immunodeficiency disorder Primary Immunodeficiencies Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more that involves combined humoral and cellular deficiencies Combined humoral and cellular immunity deficiencies Immunodeficiency disorders are associated with or predispose patients to various complications, including infections, autoimmune disorders, and lymphomas and other cancers. Primary immunodeficiencies... read more . Estimated incidence is 1 in 20,000 to 100,000 births. Ataxia-telangiectasia is caused by mutations in the gene that encodes ataxia-telangiectasia–mutated (ATM) protein. ATM is involved in detection of DNA damage and helps control the rate of cell growth and division.
Patients often lack IgA and IgE and have a progressive T-cell defect.
Symptoms and Signs of Ataxia-Telangiectasia
Age at onset of neurologic symptoms and evidence of immunodeficiency vary.
Ataxia is frequently the first symptom and usually develops when children begin to walk. Progression of neurologic symptoms leads to severe disability. Speech becomes slurred, choreoathetoid movements and nystagmus develop, and muscle weakness usually progresses to muscle atrophy.
Telangiectasias may not appear until age 4 to 6 years; they are most prominent on the bulbar conjunctivae, ears, antecubital and popliteal fossae, and sides of the neck.
Recurrent sinopulmonary infections lead to recurrent pneumonia, bronchiectasis, and chronic restrictive pulmonary disease.
Certain endocrine abnormalities (eg, gonadal dysgenesis, testicular atrophy, diabetes mellitus Diabetes Mellitus (DM) Diabetes mellitus is impaired insulin secretion and variable degrees of peripheral insulin resistance leading to hyperglycemia. Early symptoms are related to hyperglycemia and include polydipsia... read more ) may occur.
Frequency of cancer (especially leukemia Overview of Leukemia Leukemia is a malignant condition involving the excess production of immature or abnormal leukocytes, which eventually suppresses the production of normal blood cells and results in symptoms... read more , lymphoma Overview of Lymphoma Lymphomas are a heterogeneous group of tumors arising in the reticuloendothelial and lymphatic systems. The major types are Hodgkin lymphoma and non-Hodgkin lymphoma (see table Comparison of... read more , brain tumors, and gastric cancer) is high. Cancer typically occurs after age 10 and at a rate of about 1%/year but is a lifelong risk and can occur at any age.
Diagnosis of Ataxia-Telangiectasia
IgA and serum alpha-1 fetoprotein levels
Genetic testing
The following clinical findings suggest the diagnosis of ataxia-telangiectasia:
Cerebellar ataxia (particularly when telangiectasias are present)
Low levels of IgA (present in 80% of patients with this disorder)
High levels of serum alpha-1 fetoprotein
If karyotype analysis is done, chromosome breaks, consistent with a defect in DNA repair, are often seen.
Diagnosis of ataxia-telangiectasia is confirmed by identifying mutations on both alleles of the gene for ATM protein. Because carriers of an ataxia-telangiectasia mutation usually remain asymptomatic, testing siblings for a carrier state can help predict their chance of having an affected child.
Testing for endocrine abnormalities and cancers is done based on clinical presentation.
Treatment of Ataxia-Telangiectasia
Supportive care using prophylactic antibiotics or immune globulin (IgG) replacement therapy
Treatment with prophylactic antibiotics or immune globulin Replacement of missing immune components Immunodeficiency typically manifests as recurrent infections. However, recurrent infections are more likely to have causes other than immunodeficiency (eg, inadequate treatment, resistant organisms... read more may help patients with ataxia-telangiectasia.
In one small study, treatment with amantadine resulted in minimal improvement in motor function, but there is no effective treatment for the progressive neurologic deterioration, which causes death, usually by age 30.
Chemotherapy is often indicated for treatment of associated cancers.
Key Points
Ataxia-telangiectasia involves combined humoral and cellular deficiencies.
Ataxia is frequently the first symptom and usually develops when children begin to walk.
There is no effective treatment for the progressive neurologic deterioration.
