Open conformation tissue transglutaminase testing for celiac dietary assessment

Objectives: Anti tissue-transglutaminase antibody is the mainstay of celiac disease serologic testing. Whilst it has high sensitivity in patients on an unrestricted diet, sensitivity is poor for evaluation of gluten free diet adherence. Aim: To assess the utility of a novel assay measuring Immunoglobulin-A antibodies to catalytically active open conformation tissue-transglutaminase in assessment of ongoing gluten exposure in celiac disease patients on an alleged gluten free diet. Methods: Through prospective assessment, 147 patients with celiac disease were divided into good and poor adherence. Open and closed (conventional) tissue-transglutaminase titres were measured using standard enzyme linked immunosorbent assay. 50 patients with inflammatory bowel disease served as disease controls. Results: Overall 128 patients had been on gluten free diet for more than six months and 19 were found to be poorly adherent on dietary review. Within this group 13 (68.4%) and 10 (52.6%) patients respectively were positive for the open conformation and conventional assay (p= 0.51). Two and one control patients tested positive for closed and open assays respectively. Conclusions: Compared to native assays open conformation tissue-transglutaminase may have higher sensitivity in the poor gluten free diet adherence group and higher specificity in the control population. Larger population studies are warranted to assess whether the open conformation tissue-transglutaminase assay may be superior to the conventional assay.