title: Simultaneous detection of IgA and IgG antibodies against tissue transglutaminase: The preferred pre-biopsy test in childhood celiac disease.
abstract: OBJECTIVE
  IgA antibodies against tissue transglutaminase (anti-TG2) is a reliable marker of celiac disease (CD). However, IgA-deficient patients are not identified and young children may lack IgA anti-TG2. Combined detection of IgA and IgG (IgA/IgG) against deamidated gliadin peptides (DGP) has shown a high diagnostic performance for untreated CD. Here we examined the utility of IgA/IgG anti-TG2, IgA/IgG anti-DGP and IgA/IgG against a mix of TG2 and DGP (anti-TG2/DGP) in finding CD among children.
  
  
  METHODS
  Serum antibodies against TG2, DGP, and TG2/DGP were determined with ELISA in 242 children referred to a paediatric gastroenterologist. Fifty had untreated CD verified by an intestinal biopsy and 192/242 children had other diseases than CD.
  
  
  RESULTS
  Forty-eight untreated CD children had increased IgA/IgG anti-TG2, 47/50 had increased IgA/IgG anti-DGP and 46/50 had increased IgA/IgG anti-TG2/DGP. One control subject had increased IgA/IgG anti-TG2 and IgA/IgG anti-TG2/DGP, whereas 7/192 control subjects had increased IgA/IgG anti-DGP. The IgA/IgG anti-TG2 assay had the best performance with a sensitivity of 96%, a specificity of 99.5% and the area under the ROC-curve was 0.996 (95% CI 0.992-1, p < 0.0001).
  
  
  CONCLUSIONS
  Detection of one antibody is not sufficient when screening for untreated CD among children due to cases of IgA deficiency. The inclusion of DGP antigens in the IgA/IgG combination assays seems to affect the sensitivity and specificity negatively, whereas detection of IgA/IgG anti-TG2 has the potential of finding most untreated CD patients, including those with IgA deficiency.
authors.affiliation: a Departments of Women's and Children's Health , Uppsala University , Uppsala , Sweden ;
authors.forename: Ingrid
authors.initials: I
authors.lastname: Dahlbom
authors.affiliation: a Departments of Women's and Children's Health , Uppsala University , Uppsala , Sweden ;
authors.forename: Britt-Inger
authors.initials: BI
authors.lastname: Nyberg
authors.affiliation: a Departments of Women's and Children's Health , Uppsala University , Uppsala , Sweden ;
authors.forename: Lillemor
authors.initials: L
authors.lastname: Berntson
authors.affiliation: a Departments of Women's and Children's Health , Uppsala University , Uppsala , Sweden ;|b Departments of Immunology, Genetics and Pathology , Uppsala University , Uppsala , Sweden.
authors.forename: Tony
authors.initials: T
authors.lastname: Hansson
mesh_terms: D000293:Adolescent; D001323:Autoantibodies / Q000097:blood*; D001706:Biopsy; D002446:Celiac Disease / Q000097:blood / Q000175:diagnosis*; D002648:Child; D002675:Child, Preschool; D005260:Female; D019204:GTP-Binding Proteins / Q000276:immunology*; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood*; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D008297:Male; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D012372:ROC Curve; D011503:Transglutaminases / Q000276:immunology*
chemical_list: D001323:Autoantibodies; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins
keywords: Celiac disease; autoantibodies; children; gliadin; tissue transglutaminase