Ataxia telangiectasia is an autosomal recessive disorder caused by a defect in the ATM gene which encodes for DNA repair enzymes. It is one of the inherited combined immunodeficiency disorders. It typically presents in early childhood with abnormal movements.


  • Incidence: 0.03 cases per 100,000 person-years
  • Peak incidence: 1-5 years
  • Sex ratio: 1:1
<1 1-5 6+ 16+ 30+ 40+ 50+ 60+ 70+ 80+

Clinical features

  • cerebellar ataxia
  • telangiectasia (spider angiomas)
  • IgA deficiency resulting in recurrent chest infections
  • 10% risk of developing malignancy, lymphoma or leukaemia, but also non-lymphoid tumours

Differential diagnosis

Comparison of Friedreich's ataxia and ataxia telangiectasia. Note in particular how ataxia telangiectasia tends to present much earlier, often at the age of 1-2 years