title: Diagnostic value of anti-deamidated gliadin peptide IgG antibodies for celiac disease in children and IgA-deficient patients.
abstract: OBJECTIVE
  The aim of the study was to analyze the diagnostic performance of anti-deamidated gliadin peptide (dGp) immunoglobulin (Ig) G and IgA regarding the age at celiac disease (CD) diagnosis and the anti-dGp IgG usefulness for diagnosing CD IgA-deficient patients.
  
  
  METHODS
  Anti-dGp IgG and IgA and anti-native gliadin (nGlia) IgA were determined by enzyme fluoroimmunoassay in 100 newly diagnosed anti-tissue transglutaminase (tTG) IgA-positive pediatric and adult patients with CD and in 100 age-matched patients with other digestive pathologies. Anti-dGp IgG was evaluated in 6 CD IgA-deficient patients.
  
  
  RESULTS
  When analyzing all of the patients, the anti-dGp IgG assay showed higher diagnostic accuracy (area under receiver operating characteristic curve), specificity, and positive predictive value than anti-dGp IgA and anti-nGlia IgA. All of the diagnostic parameters corresponding to anti-dGp IgG reached the same values as anti-tTG IgA in children 7 years or younger. In older patients, both anti-dGp isotypes showed an inverse behavior, IgG having a higher specificity and positive predictive value but a lower sensitivity and negative predictive value than IgA. Anti-dGp levels were associated with the severity of intestinal lesions, and an inverse association was found regarding age at diagnosis. Both anti-dGp IgG and IgA were found to be positive in the 9 patients with minimal intestinal changes included in the study. All of the patients with CD with IgA deficiency were positive for anti-dGp IgG.
  
  
  CONCLUSIONS
  The diagnostic performance of anti-dGp depends on the antibody isotype and on the age at CD diagnosis, anti-dGp IgG being a serological marker at least as useful as anti-tTG IgA for detecting CD in children ages 7 years or younger. Our data also indicate that anti-dGp IgG can improve the diagnosis of IgA-deficient patients.
authors.affiliation: Department of Immunology, Hospital Universitario Central de Asturias, Oviedo, Spain. lourdes.mozo@sespa.princast.es
authors.forename: Lourdes
authors.initials: L
authors.lastname: Mozo
authors.forename: Jesús
authors.initials: J
authors.lastname: Gómez
authors.forename: Esther
authors.initials: E
authors.lastname: Escanlar
authors.forename: Carlos
authors.initials: C
authors.lastname: Bousoño
authors.forename: Carmen
authors.initials: C
authors.lastname: Gutiérrez
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D019540:Area Under Curve; D002446:Celiac Disease / Q000150:complications / Q000175:diagnosis* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D005903:Gliadin / Q000276:immunology*; D006801:Humans; D017098:IgA Deficiency / Q000150:complications*; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012372:ROC Curve; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D011503:Transglutaminases / Q000276:immunology; D055815:Young Adult
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; D005903:Gliadin; D011503:Transglutaminases