title: Early diagnosis of ataxia-telangiectasia using radiosensitivity testing.
abstract: OBJECTIVE
  To utilize radiosensitivity testing to improve early diagnosis of patients with ataxia-telangiectasia (A-T).
  
  
  METHODS
  We established normal ranges for the colony survival assay (CSA) by testing cells from 104 patients with typical A-T, 29 phenotypic normal patients, and 19 A-T heterozygotes. We also analyzed 61 samples from patients suspected of having A-T and 25 patients with related disorders to compare the CSA with other criteria in the diagnosis of A-T.
  
  
  RESULTS
  When cells were irradiated with 1.0 Gy, the mean survival fraction (microSF +/- 1 SD) for patients with A-T was 13.1% +/- 7.2% compared with 50.1% +/- 13.5% for healthy control patients. These data served to define a diagnostic range for the CSA (ie, <21%), a normal range (>36%), and a nondiagnostic intermediate range of 21% to 36%. The mutations of patients with A-T with intermediate radiosensitivity tended to cluster around the functional domains of the ATM gene.
  
  
  CONCLUSIONS
  The CSA is a useful adjunctive test for confirming an early clinical diagnosis of A-T. However, CSA is also abnormal in other chromosomal instability and immunodeficiency disorders.
authors.affiliation: Department of Pathology, UCLA School of Medicine, Los Angeles, California 90095-1732, USA.
authors.forename: Xia
authors.initials: X
authors.lastname: Sun
authors.forename: Sara G
authors.initials: SG
authors.lastname: Becker-Catania
authors.forename: Helen H
authors.initials: HH
authors.lastname: Chun
authors.forename: Mee Jeong
authors.initials: MJ
authors.lastname: Hwang
authors.forename: Yong
authors.initials: Y
authors.lastname: Huo
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Wang
authors.forename: Midori
authors.initials: M
authors.lastname: Mitui
authors.forename: Ozden
authors.initials: O
authors.lastname: Sanal
authors.forename: Luciana
authors.initials: L
authors.lastname: Chessa
authors.forename: Barbara
authors.initials: B
authors.lastname: Crandall
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gatti
mesh_terms: D001260:Ataxia Telangiectasia / Q000175:diagnosis* / Q000235:genetics; D002470:Cell Survival; D002478:Cells, Cultured / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D009154:Mutation; D010766:Phosphorylation; D011836:Radiation Tolerance / Q000235:genetics*; D012016:Reference Values; D012680:Sensitivity and Specificity; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D000509:alpha-Fetoproteins