Resurrection of gliadin antibodies in coeliac disease. Deamidated gliadin peptide antibody test provides additional diagnostic benefit

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Abstract
Objective. Circulating antibodies against naïve, whole gliadin have been replaced by more accurate endomysial and tissue transglutaminase antibody tests in the diagnosis of coeliac disease. The purpose of this study was to compare these serological tests with a new test recognizing antibodies against deamidated and defined gliadin peptides. Material and methods. The study population comprised selected coeliac disease patients in a tertiary clinic: newly detected patients before and after a gluten-free diet, patients with persistent small-bowel mucosal villous atrophy despite a strict gluten-free diet and non-coeliac controls reporting abdominal symptoms after ingestion of cereals. Comparisons were made between serum IgA-class gliadin peptide, endomysial, tissue transglutaminase and conventional gliadin antibodies. Results. The deamidated gliadin peptide antibody test showed a sensitivity of 91% and a specificity of 98% in coeliac disease. The tissue transglutaminase antibody test performed equally well. The specificity of endomysial antibody was just as high, but its sensitivity was lower, 80%. The conventional gliadin antibody test showed poor sensitivity and specificity. Combination of the deamidated gliadin peptide and tissue transglutaminase tests offered the best sensitivity without loss of specificity in the diagnosis of coeliac disease. All antibody levels declined in line with mucosal recovery. The deamidated gliadin peptide antibody test showed six of the nine cases with small-bowel mucosal damage persisting on a gluten-free diet, whereas tissue transglutaminase detected only two cases and endomysial antibody none. Conclusions. The new gliadin peptide antibody test proved highly accurate in the diagnostic work-up and follow-up of coeliac disease and can be endorsed in combination with the tissue transglutaminase test.