title: Antibodies against deamidated gliadin peptides identify adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase.
abstract: BACKGROUND
  This study was done to evaluate the diagnostic utility of antibodies against deamidated gliadin peptides compared to traditional markers for coeliac disease.
  
  
  OBJECTIVE
  To evaluate diagnostic utility of antibodies against deamidated gliadin peptide (DGP).
  
  
  METHODS
  Sera from 176 adults, referred for endoscopy without previous analysis of antibodies against tissue transglutaminase (tTG) or endomysium (EmA), were retrospectively analysed by ELISAs detecting IgA/IgG antibodies against DGP or a mixture of DGP and tTG, and compared with IgA-tTG and EmA. Seventy-nine individuals were diagnosed with coeliac disease.
  
  
  RESULTS
  Receiver operating characteristic analyses verified the manufacturers' cut-off limits except for IgA/IgG-DGP/tTG. In sera without IgA deficiency, the sensitivity was higher for IgA/IgG-DGP (0.85-0.87) compared with IgA-tTg (0.76) and EmA (0.61). All tests showed high specificity (0.95-1.00). Eighteen coeliac disease-sera were negative regarding IgA-tTG, nine of which were positive for IgA/IgG-DGP. Sera from coeliac disease-patients >70 years were more often negative for IgA-tTG (50%) and IgA/IgG-DGP (36%) than younger patients (15% and 8% respectively) (P < 0.01). Three of the four IgA-deficient patients were positive in the IgA/IgG-DGP assay.
  
  
  CONCLUSIONS
  In this study of patients unselected regarding IgA-tTg/EmA, thus unbiased in this respect, IgA/IgG-DGP identified adult coeliac disease patients negative for antibodies against endomysium and tissue transglutaminase. Serology is often negative in elderly patients with coeliac disease; a small bowel biopsy should therefore be performed generously before coeliac disease is excluded.
authors.affiliation: Department of Clinical Immunology and Transfusion Medicine, Linköping University Hospital, Linköping, Sweden. charlotte.dahle@lio.se
authors.forename: C
authors.initials: C
authors.lastname: Dahle
authors.forename: A
authors.initials: A
authors.lastname: Hagman
authors.forename: S
authors.initials: S
authors.lastname: Ignatova
authors.forename: M
authors.initials: M
authors.lastname: Ström
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000906:Antibodies / Q000097:blood*; D002446:Celiac Disease / Q000175:diagnosis*; D003429:Cross Reactions; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005903:Gliadin / Q000276:immunology / Q000378:metabolism*; D006801:Humans; D008297:Male; D008875:Middle Aged; D012698:Serologic Tests; D011503:Transglutaminases / Q000276:immunology / Q000378:metabolism; D055815:Young Adult
chemical_list: D000906:Antibodies; D005903:Gliadin; D011503:Transglutaminases