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 m 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.