American Board of Internal Medicine (ABIM) Certification Practice Exam

Which antibody is indicative of celiac disease?

1. Anti-U1 RNP

2. Anti-Scl-70

3. anti endomysial, anti tissue transglutaminase

4. anti-smooth muscle

The correct answer is: anti endomysial, anti tissue transglutaminase

Celiac disease is an autoimmune disorder that primarily affects the gastrointestinal tract in individuals who are genetically predisposed to gluten intolerance. The presence of specific antibodies is key in diagnosing this condition. The most commonly used antibodies to identify celiac disease are anti-endomysial antibodies and anti-tissue transglutaminase antibodies. Anti-endomysial antibodies are directed against the endomysium, a connective tissue that surrounds muscle fibers, while anti-tissue transglutaminase antibodies target an enzyme that plays a crucial role in the metabolism of gluten and the immune response related to it. The presence of these antibodies indicates an autoimmune response triggered by the ingestion of gluten in susceptible individuals, leading to the characteristic intestinal damage associated with celiac disease. In contrast, other antibodies listed—such as anti-U1 RNP, anti-Scl-70, and anti-smooth muscle antibodies—are associated with different autoimmune conditions (like mixed connective tissue disease, systemic sclerosis, and autoimmune hepatitis, respectively) and are not indicative of celiac disease. Therefore, the identification of anti-endomysial antibodies and anti-tissue transglutaminase antibodies is considered the primary serological test for diagnosing celiac disease.