The cytogenetics of ataxia telangiectasia.

Ataxia-telangiectasia (AT) is a heterogeneous autosomal recessive disorder marked by cerebellar ataxia, oculocutaneous telangiectases, hypersensitivity to ionizing radiation, immunodeficiency, and cancer susceptibility. AT is also a spontaneous chromosomal breakage syndrome, notable for tissue-specific cytogenetic changes and telomeric fusions. Molecular characterization of rearrangements specific to T-lymphocytes suggests that a DNA repair/processing defect is potentially responsible for the diverse array of chromosomal abnormalities observed in a variety of AT cell types.