title: New serology assays can detect gluten sensitivity among enteropathy patients seronegative for anti-tissue transglutaminase.
abstract: BACKGROUND
  Some patients with celiac disease (CD) may be seronegative with the commonly used test for IgA anti-tissue transglutaminase (anti-tTG) antibodies. Our aim was to explore whether newer assays incorporating synthetic deamidated gliadin-related peptides (DGPs) or other TG isoenzymes as antigen are useful for detecting gluten sensitivity in IgA anti-tTG-seronegative patients.
  
  
  METHODS
  We assayed serum samples obtained at diagnosis from (a) anti-tTG-seronegative patients with a CD-like enteropathy (n = 12), (b) skin biopsy-proven dermatitis herpetiformis (DH) patients (n = 26), and (c) IgA anti-tTG-positive CD patients (n = 26). All patients had typical total IgA concentrations. All patients underwent intestinal biopsy and serum testing for (a) detection of IgA and IgG isotypes of both anti-DGP and anti-tTG in a single assay (tTG/DGP Screen; INOVA Diagnostics), (b) simultaneous detection of both IgA and IgG anti-DGP antibody isotypes (DGP Dual; INOVA Diagnostics), and (c) detection of antibodies to transglutaminase 3 (TG3) or transglutaminase 6 (TG6).
  
  
  RESULTS
  All anti-tTG-seropositive patients also tested positive in anti-DGP assays. Overall, tTG/DGP Screen detected 6 (31.6%) of the 19 anti-tTG seronegatives, and anti-DGP Dual produced positive results in 5 (26.3%) of these cases. Whereas both assays detected 2 anti-tTG-negative DH patients with partial villous atrophy, they were positive in only 2 of the 5 cases with no histologically discernible mucosal damage. Testing for antibodies to TG3 and TG6 identified 7 (36.8%) of the 19 anti-tTG-negative patients, 5 of which were also positive for anti-DGP.
  
  
  CONCLUSIONS
  Detection of anti-DGP with tTG/DGP Screen or anti-DGP Dual, or detection of antibodies to other TG isoenzymes, enhances the sensitivity for detecting gluten sensitivity among non-IgA- deficient, anti-tTG-seronegative patients with CD-like enteropathy.
authors.affiliation: Small Bowel Section, Department of Medicine, C. Bonorino Udaondo Gastroenterology Hospital, Buenos Aires, Argentina.
authors.forename: Emilia
authors.initials: E
authors.lastname: Sugai
authors.forename: Hui Jer
authors.initials: HJ
authors.lastname: Hwang
authors.forename: Horacio
authors.initials: H
authors.lastname: Vázquez
authors.forename: Edgardo
authors.initials: E
authors.lastname: Smecuol
authors.forename: Sonia
authors.initials: S
authors.lastname: Niveloni
authors.forename: Roberto
authors.initials: R
authors.lastname: Mazure
authors.forename: Eduardo
authors.initials: E
authors.lastname: Mauriño
authors.forename: Pascale
authors.initials: P
authors.lastname: Aeschlimann
authors.forename: Walter
authors.initials: W
authors.lastname: Binder
authors.forename: Daniel
authors.initials: D
authors.lastname: Aeschlimann
authors.forename: Julio C
authors.initials: JC
authors.lastname: Bai
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002446:Celiac Disease / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D007070:Immunoglobulin A / Q000097:blood; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012698:Serologic Tests; D011503:Transglutaminases / Q000097:blood*; D055815:Young Adult
chemical_list: D007070:Immunoglobulin A; D007074:Immunoglobulin G; C498712:TGM3 protein, human; C532876:TGM6 protein, human; D011503:Transglutaminases