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Dr. Andrew Rynne
Dr. Andrew Rynne

Family Physician

Exp 50 years

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Article Home Children's Health Ataxia Telangiectasia

Ataxia Telangiectasia

Ataxia-telangiectasia (A-T) is an autosomal recessive, complex, multisystem disorder characterized by progressive neurologic impairment, cerebellar ataxia, and variable immunodeficiency with susceptibility to sinopulmonary infections, impaired organ maturation, x-ray hypersensitivity, ocular and cutaneous telangiectasia, and a predisposition to malignancy.


  • The responsible gene (ATM gene) has been mapped to band 11q22-23.
  • The ATM gene encodes the protein kinase ATM, which is the key regulator of cellular response to double-strand breaks (DSB) in DNA.
  • Abnormal sensitivity of ataxia-telangiectasia cells to x-rays and certain radiomimetic chemicals but not to ultraviolet irradiation, which leads to chromosome and chromatid breaks.
  • ATM mutations are poor prognostic factor in patients with lung cancer
  • ATM gene targets include well-known tumor suppressor genes such as TP53 and BRCA1, both of which play an important role in the predisposition to breast cancer.
  • Studies of ataxia-telangiectasia families have consistently reported an increased risk of breast cancer in women with one mutated ATM gene.

Clinical types

  • Pure A-T where patients present with all/most of the diagnostic symptoms
  • Attenuated A-T where sufferers do not possess all of the diagnostic symptoms.
  • Carrier A-T where individuals with a single ATM mutation show an increased risk of cancer 

These are sometimes classified into ‘types’ from I to IV.

  • Type I is the classic syndrome with all manifestations.
  • Type II lacks some of the typical findings but shows radio sensitivity.
  • Type III has the classic clinical findings but is not radiosensitive.
  • Type IV shows only some clinical features and is not radiosensitive.

Signs and symptoms


  • Ataxia has its onset in infancy, becoming apparent when the child begins to walk (usually from 12-14 month).
  • From this early stage, ataxia is associated with abnormal head movements and is slowly and steadily progressive.
  • Ataxia is relentlessly progressive, but the pace is variable
  • At a typical rate of progression, the child requires a wheelchair by age 10 or 11 years, even when muscular strength continues to be good. 

Other neurologic symptoms

  • Dyssynergia and intention tremor of the extremities become prominent features with age.
  • Myoclonic jerks of the trunk and the extremities
  • Choreoathetosis is the most prominent extra pyramidal feature in ataxia-telangiectasia.
  • The facies is usually relaxed, dull, sad, and seemingly inattentive, which is in sharp contrast to the cheerful, alert appearance when the patient is smiling.
  • Dystonic posturing of the fingers is characteristic.
  • About 30% of patients have mild mental retardation


  • Telangiectasias are a second major clinical manifestation (nonneurologic) of the disease
  • Dilated conjunctivae vessels, first noticed in the angles of both eyes, spread horizontally in the equatorial region of the conjunctivae toward the corneal limb.
  • Ocular telangiectasias may be mistaken for conjunctivitis
  • Telangiectatic vessels of ataxia-telangiectasia very rarely hemorrhage 

Skin changes

  • Progeric changes of hair and skin are a cardinal feature of ataxia-telangiectasia.
  • Some gray hairs are usually found, even in young children if carefully looked for.
  • The facial skin tends to become atrophic and sclerodermoid in adolescence.
  • The ears tend to become inelastic.
  • Café au lait spots, usually single rather than multiple
  • Frequent hyperpigmented macules resembling large freckles.
  • Seborrheic dermatitis; keratosis pilaris; common warts; and, in female patients, hirsutism of the arms and the legs are also frequently found. 


  • In children, more than 85% of neoplasm cases are acute lymphocytic leukemia or lymphoma. In adults with ataxia-telangiectasia, solid tumors are more frequent.
  • Solid tumors include lung cancer, stomach cancer, breast cancer, medulloblastoma, basal-cell carcinoma, ovarian dysgerminoma, hepatoma, uterine leiomyoma, parotid gland cancer, and thyroid cancer. 
  • The stunting of growth is not well understood.Chronic sinopulmonary disease may be a contributing factor, but stunting of growth also occurs in its absence.

Tests and diagnosis

  • Laboratory markers are important for both diagnosis and prognosis. The most constant markers are elevated levels of AFP and carcinoembryonic antigen
  • Chromosomal abnormalities, especially inversions and translocations involving chromosomes 7 and 14, though neither of these abnormalities is always found
  • The dysgammaglobulinemia of ataxia-telangiectasia includes an absent or low level of IgA, including secretory IgA, a normal or low level of IgG, and an elevated or normal level of IgM.
  • IgA deficiency is found in about 70% of patients with ataxia-telangiectasia syndrome.
  • MRI and sporadically made CT scan often show evidence of nonspecific cerebellar atrophy with widened cerebellar sulci and enlargement of the fourth ventricle.
  • Chest radiographs may show a small or absent thymic shadow, decreased mediastinal lymphoid tissue, and pulmonary changes similar to those seen in cystic fibrosis. 


  • The life span of patients with ataxia-telangiectasia clearly has been prolonged by antibiotic treatment.
  • Prevention of infections by regular injection of immunoglobulins is considered useful.
  • Fetal thymus implants and stimulants of the immunologic system have given inconclusive results.
  • Treatment of neurologic manifestations is disappointing. Beta-adrenergic blockers may improve fine motor coordination in some cases.
  • Desferrioxamine has been shown to increase genomic stability of ataxia-telangiectasia cells and, therefore, may present a promising tool in ataxia-telangiectasia treatment.
  • Antioxidants in ataxia-telangiectasia patients have been constructed and are currently underway.