Cover: Extrachromosomal telomeric DNA in patients with Ataxia-telangiectasia (AT). Shown are fibroblast metaphase chromosomes from a patient with AT hybridized with Cy-3 labeled peptide nucleic acid probe specific for telomeric repeats (lighting up in yellow). The frequency of signals not attached to chromosomes stained with DAPI (blue) was found to be increased in both Atm-/- mice and patients with AT. See Report by Hande et al. in this issue, pp. 519-528.
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