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Tissue Transglutaminase Antibody
Celiac disease and dermatitis herpetiformis, the two recognized forms of gluten sensitive enteropathy (GSE) are characterized by chronic inflammation on the intestinal mucosa and flattening of the epithelium or positive "villous atrophy." Intolerance to gluten, the protein of wheat, rye and barley causes GSE. Patients with celiac disease may suffer other diverse side effects or they may be asymptomatic. Dermatitis herpetiformis is a skin disease associated with GSE. All GSE patients have increased risk of lymphoma. A gluten-free diet controls GSE and associated risks.
The development of serum tests for three different antibodies of the IgA isotype made it possible to generate more rapid, revised European Society for Pediatric Gastroenterology and Nutrition (ESPGAN) criteria for celiac disease as reported in 1990. These tests include IgA endomysial antibodies (EMA), IgA Anti-Gliadin Antibodies (AGA) and R1 Antireticulin Antibodies (ARA). The revised ESPGAN criteria call for: a) a single positive gut biopsy and b) the demonstration of at least two of the three IgA class antibodies mentioned above. Since then, several studies have demonstrated that IgA EMA tests have over 99% specificity for GSE and a greater sensitivity than ARA or AGA tests. Since the IgA EMA disappear when patients with celiac disease or dermatitis herpetiformis adhere to a gluten-free diet, tests for these antibodies also aid in checking on the adherence of patients to their diets.
Recently, the endomysial antigen has been identified as the protein cross-linking enzyme known as Tissue Transglutaminase (tTG). Antigen specific ELISA procedures incorporating tTG afford a reliable, objective alternative to the traditional immunofluorescent-based assays incorporating thin sections of primate esophagus as substrate.
The assay for IgA antibodies to Tissue Transglutaminase (tTG) is a complementary test to the Anti-Gliadin Antibody Assay. Both the Anti-Gliadin and tTG Assays are aids in diagnosing celiac disease and other diseases linked to celiac disease. The tTG Assay should be ordered when either Anti-Gliadin IgG, IgA or both are elevated. In instances where celiac disease and its linked diseases are suspected both tests, the tTG and Anti-Gliadin, could be requested simultaneously.