Antibodies Against Deamidated Gliadin as New and Accurate Biomarkers of Childhood Coeliac Disease

ABSTRACT Objectives: Assays of tissue transglutaminase antibodies (anti‐tTG) represent the cornerstone of serological coeliac disease (CD) diagnostics. Assays of antibodies against native gliadin (anti‐nGli) lost importance due to low validity. We investigated the performance of new assays for antibodies against deamidated gliadin (anti‐dGli) in childhood CD. Methods: We retrospectively compared children (142 with active CD and 160 without CD, diagnosis confirmed or excluded by intestinal biopsy) concerning (immunoglobulin [Ig] G and IgA) anti‐nGli, anti‐tTG, and 2 different anti‐dGli assays. Results: IgG‐anti‐dGli1, IgG‐anti‐dGli2, and IgA‐anti‐tTG performed similarly. Area under the receiver‐operating characteristic curve (AUC) was 98.6%, 98.9%, and 97.9%; accuracy was 94.7%, 95.7%, and 96.7%. Anti‐dGli1 and anti‐dGli2 (IgG and IgA) and IgA‐anti‐tTG performed significantly better than IgA‐anti‐nGli and IgG‐anti‐nGli. Both IgG‐anti‐dGli showed higher AUC and accuracy than IgA‐anti‐dGli and IgG‐anti‐tTG. Combined evaluation of IgA‐anti‐tTG with one of the IgG‐anti‐dGli tests reduced the rate of falsely classified patients. At enhanced cutoff (specificity >99%), sensitivity was above 67% for both IgG‐anti‐dGli and IgA‐anti‐tTG. If IgA‐anti‐tTG assay was combined with one of the IgG‐anti‐dGli tests, then the fraction of patients identified with more than 99% specificity as coeliacs increased significantly above 84.5%. Combined evaluation of the 2 IgG‐anti‐dGli tests did not improve the performance. Conclusions: The new IgA and IgG‐anti‐dGli tests outperform conventional anti‐nGli assays. The validity of IgG‐anti‐dGli cannot be distinguished from IgA‐anti‐tTG. It should be studied prospectively whether antibody assays could replace biopsy in diagnosis of CD in a substantial segment of children.