Medical Definition of Ataxia-telangiectasia
An intriguing autosomal recessive disorder in which a single defective gene produces myriad and protean effects, presents with cerebellar ataxia, telangiectasias in the eyes and skin, immune deficiency and autoimmune phenomena, propensity for lymphoid and other malignancies, excessive sensitivity to ionising radiation, increased serum alpha-fetoprotein concentrations and a tendency for chromosome breakage and translocation.
A syndrome characterised by choreoathetosis beginning in childhood, progressive cerebellar ataxia, telangiectasis of conjunctiva and skin, slowly progressive mental deterioration and increasing cerebellar degeneration.
There is evidence that heterozygotes show an increased susceptibility to malignancy as well, with breast cancer often cited. The gene was localised by linkage studies to chromosome 11q22-23, and recently cloned, revealing it to be homologous to the PI-3 kinase family so that prenatal diagnosis by RFLP analysis is possible.
Other related genes are suspected to exist. Diagnosis in affected patients is made on clinical grounds, by detection of high concentrations of alpha-fetoprotein, and by a specialised cell culture assay for radiosensitivity and atypical radioresistant DNA synthesis. These cell culture methods are also used for prenatal diagnosis.
A characteristic autopsy feature of ataxia-telangiectasia is the presence of empty basket cells in the cerebellum which results from degeneration of the previously contained Purkinje cells.
Inheritance: autosomal recessive.
(16 Dec 1998)
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