title: Diagnostic performance of IgG anti-deamidated gliadin peptide antibody assays is comparable to IgA anti-tTG in celiac disease.
abstract: BACKGROUND
  Detection of IgG antibodies against deamidated gliadin peptides (DGP) is more sensitive and more specific for celiac disease than detection of IgG antibodies against native gliadin. Our aim was to evaluate the technical performance and diagnostic accuracy of four commercial IgG anti-DGP assays.
  
  
  METHODS
  Commercial IgG anti-DGP assays from Euroimmun, Inova, Phadia and The Binding Site were evaluated and their diagnostic accuracy (sensitivity and specificity) compared to other serologic assays for celiac disease (3IgA and 2IgG anti-tTG assays, 1IgA and 1IgG anti-gliadin assay, 1IgA anti-DGP assay). The study population consisted of 86 consecutive CD patients and 741 disease controls.
  
  
  RESULTS
  The technical performance (linearity, interference and imprecision) of the IgG anti-DGP assays was acceptable. The sensitivity of the IgG anti-DGP assays varied between 76.7% and 86.0% at the cut-off recommended by the manufacturer and between 74.4% and 86.0% at the cut-off that corresponded to a specificity of 98%. The specificity varied between 97.3% and 99.3%. The diagnostic accuracy of the IgG anti-DGP assays was comparable to the diagnostic accuracy of the IgA anti-tTG assays. The sensitivity of the IgG anti-DGP assays was significantly better than sensitivity of the IgG anti-tTG assays (p<0.05) and the specificity was significantly better than the IgA and IgG anti-gliadin assays (p<0.05).
  
  
  CONCLUSIONS
  The overall performance of the four IgG anti-DGP assays was acceptable and the diagnostic accuracy comparable to the three IgA anti-tTG assays.
authors.affiliation: Laboratory Medicine, Immunology, University Hospitals Leuven, Catholic University of Leuven, Leuven, Belgium.
authors.forename: Pieter
authors.initials: P
authors.lastname: Vermeersch
authors.forename: Karel
authors.initials: K
authors.lastname: Geboes
authors.forename: Godelieve
authors.initials: G
authors.lastname: Mariën
authors.forename: Ilse
authors.initials: I
authors.lastname: Hoffman
authors.forename: Martin
authors.initials: M
authors.lastname: Hiele
authors.forename: Xavier
authors.initials: X
authors.lastname: Bossuyt
mesh_terms: D000293:Adolescent; D000328:Adult; D000577:Amides / Q000378:metabolism*; D001706:Biopsy; D016022:Case-Control Studies; D002446:Celiac Disease / Q000097:blood / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D002648:Child; D015331:Cohort Studies; D004386:Duodenum / Q000473:pathology; D005260:Female; D019204:GTP-Binding Proteins / Q000276:immunology*; D005903:Gliadin / Q000276:immunology* / Q000378:metabolism*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood / Q000276:immunology; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology*; D016014:Linear Models; D008297:Male; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*; D011503:Transglutaminases / Q000276:immunology*
chemical_list: D000577:Amides; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D005903:Gliadin; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins