National Cancer Institute®
Last Modified: June 1, 2002
UI - 11714443
AU - Tachibana A; Tatsumi K; Furuno-Fukushi I; Sasaki MS
TI - High frequency of deletions at the hypoxanthine-guanine phosphoribosyltransferase locus in an ataxia-telangiectasia lymphoblastoid cell line irradiated with gamma-rays.
SO - Jpn J Cancer Res 2001 Nov;92(11):1190-8
AD - Radiation Biology Center, Kyoto University, Yoshida-Konoecho, Sakyo-ku, Kyoto 606-8501. email@example.com
The molecular nature of gamma-ray-induced mutations at the hypoxanthine-guanine phosphoribosyltransferase (HPRT) locus in an ataxia-telangiectasia (A-T) lymphoblastoid cell line was investigated. Twelve of 15 gamma-ray-induced HPRT-deficient mutants showed deletions. Eight of them had lost the entire HPRT gene, one showed a 1.9-kb deletion, and three had deletions of about 40-150 base pairs. Of the eight mutants that lost the entire gene, five had also lost both DXS79 and DXS86, flanking markers of the HPRT locus. The spectrum of mutations induced by gamma-irradiation in the A-T cells showed a high frequency of deletions in comparison with that in a control cell line, WIL2-NS. Sequence analysis of breakpoint junctions in four mutants revealed that three of them had junctions between short identical sequences at each breakpoint, leaving one copy at the junction. These results suggest that non-homologous end-joining is the major mechanism for deletion formation in A-T cells.
UI - 11981817
AU - Pan Q; Petit-Frere C; Lahdesmaki A; Gregorek H; Chrzanowska KH;
TI - Hammarstrom L Alternative end joining during switch recombination in patients with ataxia-telangiectasia.
SO - Eur J Immunol 2002 May;32(5):1300-8
AD - Division of Clinical Immunology, IMPI, Karolinska Institutet at Huddinge Hospital, and Center for Biotechnology and Center for Oral Biology, NOVUM, Huddinge, Sweden.
Ataxia-Telangiectasia (A-T) and Nijmegen breakage syndrome (NBS) are recessive genetic diseases with similar cellular phenotypes that are caused by mutations in the recently described ATM (encoding ATM) and NBS1 (encoding p95) genes, respectively. Both disorders are accompanied by immunodeficiency in a majority of patients, but the mechanism involved has as yet not been established. We demonstrate that in cells from A-T patients, the switch (S) recombination junctions are aberrant and characterized by a strong dependence on short sequence homologies and devoid of normally occurring mutations around the breakpoint. A low number of S fragments were generated in cells from NBS patients and showed only limited dependence on sequence identity and mutation frequencies were similar to those observed in normal controls. We propose that ATM and p95 are both involved in the final step(s) in class switch recombination with related, but disparate, functional roles. Thus, the general pathway involved in DNA repair also has a major influence on the immunoglobulin isotype switching process.
UI - 11774566
AU - Becker-Catania SG; Gatti RA
TI - Ataxia-telangiectasia.
SO - Adv Exp Med Biol 2001;495():191-8
AD - Department of Psychiatry and Biobehavioral Science, UCLA School of Medicine, Los Angeles, CA 90095, USA.
UI - 11481721
AU - Klein C; Stewart GS; Quinn NP; Taylor AM
TI - Ataxia without telangiectasia revisited: update on genetic findings in two brothers with an ataxia-telangiectasia-like disorder.
SO - Mov Disord 2001 Jul;16(4):788-9
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