Comparative Usefulness of Deamidated Gliadin Antibodies in the Diagnosis of Celiac Disease

Background & Aims: Serologic tests are used frequently in celiac disease diagnosis. Gliadin antibodies generally lack the accuracy required for proper diagnosis. We evaluated the value of deamidated gliadin antibody measurements in the diagnosis and follow-up evaluation of celiac disease and compared their potential usefulness with that of gliadin and tissue-transglutaminase antibodies. Methods: We tested deamidated gliadin, gliadin, and tissue-transglutaminase-immunoglobulin (Ig)A and -IgG in 216 biopsy-selected subjects including 92 biopsy-proven untreated celiac patients (46% with total villous atrophy and 54% with partial villous atrophy) and 124 biopsy-proven nonceliac controls. Fifty-nine celiac patients also were tested after treatment with a gluten-free diet. Antibodies were measured by commercial enzyme-linked immunosorbent assays. Deamidated gliadin-IgA+G was detected using a conjugate reactive to both isotypes, which gives a positive if either isotype is present. Results: The sensitivity, specificity, and accuracy of deamidated gliadin-IgA (74%, 95%, and 86%), deamidated gliadin-IgG (65%, 98%, and 84%), and deamidated gliadin-IgA+G (75%, 94%, and 86%) were superior to gliadin-IgA (63%, 90%, and 79%) (P < .05) and gliadin-IgG (42%, 90%, and 69%) (P < .01), and were similar to tissue-transglutaminase-IgA (78%, 98%, and 90%) before treatment. The sensitivity of IgA isotype for all tests was significantly greater in celiac patients with total villous atrophy compared with those with partial villous atrophy (P < .05). The proportion of positive test results for all tests decreased significantly after treatment (P < .0001). Conclusions: Deamidated gliadin antibody is a better diagnostic test for celiac disease than the conventional gliadin antibody testing; although histopathology remains the gold standard test for diagnosis of celiac patients.