Usefulness of Antibodies to Deamidated Gliadin Peptides in Celiac Disease Diagnosis and Follow-up

Abstract

The prevalence of the recently described deamidated gliadin peptide antibodies was compared with that of the routinely used antigliadin, antiendomysial, and tissue transglutaminase antibodies in the sera of 128 untreated celiac patients and 134 controls. Sensitivity and specificity for celiac disease were 83.6 and 90.3% for IgA and 84.4 and 98.5% for IgG antibodies to deamidated gliadin peptides. The new test displayed higher diagnostic accuracy than antigliadin antibodies and, although less sensitive than antiendomysial and tissue transglutaminase antibodies, showed significantly higher specificity than tissue transglutaminase antibodies (P < 0.001). Persistence of peptide antibodies after gluten withdrawal was an expression of low compliance with the diet and of the lack of improvement of the intestinal mucosa. The combined use of tissue transglutaminase and deamidated gliadin peptide antibodies seems to be a very useful tool for celiac disease diagnosis. Moreover, antibodies to deamidated gliadin peptides can be helpful in disease follow-up.

Performance of Serology Assays for Diagnosing Celiac Disease in a Clinical Setting

“…The extremely low sensitivity obtained may be due to the facts that the IgA Abs have higher avidity to the tTG antigen and therefore that subsequent IgG Ab binding is reduced (34). The DGP (IgGϩIgA) screen has been reported by others as an excellent substitute for the previous nonspecific Gliadin assays (2,26,28,29,36). In our study, the sensitivity of the DGP (IgGϩIgA) screen was higher and the specificity was lower than those reported in two recent studies (29,36).…”

“…The EMA assay is known for its high sensitivity and specificity for diagnosing CD but requires much technologist labor and yet suffers from interobserver variability in interpretation. Abs to deamidated gliadin peptides (DGP) were shown to be of diagnostic value, and DGP Ab kits are being extensively evaluated (2,28,29,32,36). A DGP assay recognizing both IgA and IgG Abs, known as the DGP (IgAϩIgG) screen, is intended for detecting both IgA-deficient and IgA-sufficient CD patients.…”

Serological testing for celiac disease in adults

“…These criteria were met by the studies listed in Table 1. 10,11,[17][18][19][20][21][22][23][24] Sensitivities, specificities, study prevalences together with positive predictive values (PPV) and negative predictive values (NPV) are shown whenever these where reported (definition of the terms according to Jørgensen et al, 25 Table 2). Because information of normal distribution of data was rarely given, it was decided to use nonparametric median and ranges.…”

“…b The amount of numbers is equal to the amount of references used in calculating sensitivity, specificity, PPV and NPV of the different assays. 10,11,[17][18][19][20]24 The finding of medians is based on sensitivities, specificities, PPVs (positive predictive values) and NPVs (negative predictive values) specified in a 95% confidence interval (CI). The assays are: EMA (endomysial antibodies), tTG (tissue transglutaminase antibodies) and DGP (deamidated gliadin peptide antibodies) further separated into IgG (immunoglobulin A-and G-class antibodies).…”

“…6,7 The AGA test was developed in the early 1980s, and more recently developed assays may have higher sensitivities and specificities than AGA, which is considered obsolete. [8][9][10][11][12][13] The recently introduced deamidated gliadin peptide antibody (DGP) has shown promising performance as compared to EMA and tTG test results. [6][7][8][9][13][14][15] Data and experience concerning the usage of DGP are still preliminary, however.…”