title: Two-tier analysis of histone H2AX phosphorylation allows the identification of Ataxia Telangiectasia heterozygotes.
abstract: OBJECTIVE
  Ataxia Telangiectasia (A-T) heterozygotes constitute 0.36-1% of the general population. They have a higher risk of developing several types of cancer and may be more likely to suffer side-effects following radiotherapy than the general population. Their identification is both labor- and time-consuming and the sensitivity and specificity of the methods employed has not been evaluated. This paper describes a new approach to the identification of A-T heterozygotes based on a two-tier analysis of histone H2AX phosphorylation.
  
  
  METHODS
  We compared the T-cell phenotype after exposure to 2 Gy in nine obligate A-T heterozygotes and 17 normal donors. Examined end points were histone H2AX phosphorylation by flow cytometry 1 h after irradiation (kinase proficiency) and the residual gamma-H2AX foci by confocal microscopy 72 h after irradiation (DSB repair proficiency).
  
  
  RESULTS
  The sequential use of these two methods results in 100% positive predictive value (PPV), 67% negative predictive value (NPV), 78% sensitivity, and 100% specificity. The overall hit rate, i.e. the ratio between the true positives plus the true negatives and the total number of observations was 85%.
  
  
  CONCLUSIONS
  A-T heterozygotes can be identified by analysing irradiated T-cell H2AX phosphorylation level and residual gamma-H2AX foci.
authors.affiliation: Department of Clinical and Biological Sciences, University of Turin, Italy. paola.porcedda@unito.it
authors.forename: Paola
authors.initials: P
authors.lastname: Porcedda
authors.forename: Valentina
authors.initials: V
authors.lastname: Turinetto
authors.forename: Luca
authors.initials: L
authors.lastname: Orlando
authors.forename: Erica
authors.initials: E
authors.lastname: Lantelme
authors.forename: Alfredo
authors.initials: A
authors.lastname: Brusco
authors.forename: Mario
authors.initials: M
authors.lastname: De Marchi
authors.forename: Antonio
authors.initials: A
authors.lastname: Amoroso
authors.forename: Umberto
authors.initials: U
authors.lastname: Ricardi
authors.forename: Dario
authors.initials: D
authors.lastname: Gregori
authors.forename: Claudia
authors.initials: C
authors.lastname: Giachino
mesh_terms: D000328:Adult; D001260:Ataxia Telangiectasia / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006579:Heterozygote; D006657:Histones / Q000032:analysis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010766:Phosphorylation; D010770:Phosphotransferases; D012680:Sensitivity and Specificity
chemical_list: D006657:Histones; D010770:Phosphotransferases