Antibodies against synthetic deamidated gliadin peptides and tissue transglutaminase for the identification of childhood Celiac disease

Background & Aims: Children with celiac disease have antibodies against gliadin, tissue transglutaminase (tTG), or both antigens. The aim was to evaluate immunoglobulin (Ig)A and IgG antibodies to synthetic deamidated gliadin peptides (DGP) and human tTG as screening markers for childhood celiac disease. Methods: Antibodies were detected in enzyme-linked immunosorbent assay using antihuman IgA, IgG, or a combined conjugate of IgA and IgG (IgAG) against DGP, tTG, or both (DGP/tTG), in sera from 119 children with celiac disease, 57 disease controls, and 398 blood donors. Treatment with a gluten-free diet was evaluated in 20 children with celiac disease who were followed up for 6 months from diagnosis. Results: The highest sensitivity was accounted for IgAG-DGP/tTG at 100% (119 of 119), followed by IgA-tTG at 97% (115 of 119), IgG-DGP at 95% (113 of 119), IgA-DGP at 91% (108 of 119), and IgG-tTG at 13% (15 of 119). With respect to disease controls and blood donors, specificity was for IgAG-DGP/ tTG at 89% (51 of 57) and at 97% (385 of 398), IgA-tTG at 96% (55 of 57) and at 98% (392 of 398). IgG-DGP at 86% (49 of 57) and at 99% (395 of 398), IgA-DGP at 91% (52 of 57) and at 92% (366 of 398). and IgG-tTG at 100%, respectively. The concordances between antibody assays were 87%-98%, except for comparisons with IgG-tTG (39%-41%). After 6 months of a gluten-free diet, the mean antibody levels decreased for all test results (P <.001). Conclusions: The combined IgAG-DGP/tTG assay is recommended as a front-line screening test for the identification of childhood celiac disease and also could be used as a marker of dietary compliance.