Rare ataxia manifesting at onset of walking, abnormal eye movements, telangiectasias of face and conjunctiva (presenting at 3-6 years), increased risk of infection and neoplasm, variable choreoathetoid movements, and mental retardation. Death usually occurs by 10 years of age. Defect in DNA repair causes abnormal immunoglobulins. Elevated alpha-fetoprotein is diagnostic serum marker. Condition is autosomal recessive.