Ataxia Telangiectasia

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Definitive

Male or female patient with either increased radiation induced chromosomal breakage in cultured cells, or progressive cerebellar ataxia, who has disabling mutations on both alleles of ATM.

Probable

Male or female patient with progressive cerebellar ataxia and three out of the following four findings:

  1. Ocular or facial telangiectasia
  2. Serum IgA at least 2 SD below normal for age
  3. Alpha fetoprotein at least 2 SD above normal for age
  4. Increased radiation induced chromosomal breakage in cultured cells

Possible 

Male or female patient with progressive cerebellar ataxia and at least one of the following four findings:

  1. Ocular or facial telangiectasia
  2. Serum IgA at least 2 SD below normal for age
  3. Alpha fetoprotein more than 2 SD above normal for age
  4. Increased chromosomal breakage after exposure to irradiation

Spectrum of disease

 
AT is a progressive neurologic disorder. Most patients begin to have difficulty walking at the end of the first year of life and are wheelchair bound by the teenage years. Ocular or facial telangiectasia are usually noted at 4-8 years of life. Many patients have recurrent respiratory infections. Leukemia or lymphomas are seen in 10-15% of patients and may be the presenting finding. Some patients are not recognized to have AT until the second decade of life.

Differential diagnosis 

Nijmegen breakage syndrome