engleski

Novel serologic marker for coeliac disease- antibodies against deamidated gliadin

Objectives and Study: Coelic disease (CD) is an immunemediated enteropathy cause by a permanent sensitivity to gluten in genetically susceptible individuals. It is recommended to perform serological test for CD in children with failure to thrive, persistent diarrhea or other persisting gastrointestinal symptoms and in asymptomatic children who have conditions associated with CD. There are different serological tests for detecting CD: anti-tissue transglutaminase IgA (tTG), anti-endomysium IgA (EMA), anti-gliadin IgA and IgG (AGA IgA and AGA IgG) antibodies. Measurement of anti-tTG IgA is recommended for initial testing for CD. Recently it was shown that antibodies recognizing partially deamidated gliadin have higher sensitivity and specificity for CD in comparison to antibodies recognizing native gliadin. The aim of the study was to assess the diagnostic performance of new ELISA test in which the antigen represents a repetitive motive of deamidated gliadin peptides (GAF-3X) and to compare it with anti-tTG test. Methods: Study included 56 pediatric patients (F/M = 37/19 ; median age 11 years (range 7–15), for whom CD serology was requested. Anti-GAF-3X IgA and IgG together with anti-tTG IgA antibodies were measured in all sera using ELISA assays (Euroimmun, Lu¨beck, Germany). Manufacturer proposed cut off values were 20 RU/mL for anti- tTG and 25RU/ml for GAF-3X IgA and IgG. Results: Out of 56 patients 8 were positive for all 3 autoantibodies type, 1 for GAF-3X IgA and anti-tTG, 13 for antitTG and 1 for anti-GAF-3X IgA only. CD was biopsy confirmed in 14 patients of whom 7 were positive for all 3 autoantibodies type, 1 for anti-tTG and GAF-3X IgA and 2 for anti-tTG only. The residual 4 CD confirmed patients were on gluten free diet and 3 of them were seronegative while anti-tTG was positive in one. With cut off values proposed by the manufacturer sensitivity and specificity was 100% and 73, 8% for anti-tTG, 80, 0% and 95, 2% for anti- GAF-3X IgA and 70.0% and 97.6% for anti-GAF-3X IgG. According to ROC analysis, sensitivity and specificity for anti-tTG IgA was 100% and 95.2%, for anti-GAF-3X IgA 90.0% and 92.9%, and for anti-GAF-3X IgG 70.0% and 97.6% RU/mL, respectively. Optimal cut-off value for tTG-IgA was 48.6 RU/mL, and 22 RU/mL for both anti-GAF-3X IgA and anti-GAF-3X IgG. The correlation between anti-tTG IgA and GAF-3X IgA or GAF-3X IgG was weak, but statistically significant (P<0.001). Conclusion: Determination of anti-GAF-3X along with antitTG with the use of appropriate cut off values can increase the overall sensitivity and specificity of CD screening panel.Anti-GAF-3X could be a better marker of dietary compliance than anti-tTG.

coeliac disease ; autoantibodies ; tTG ; children

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