Antiendomysial antibody is use in the diagnosis of-
**Core Concept**
Antiendomysial antibody (EMA) is a type of autoantibody directed against the smooth muscle proteins of the endomysium, a layer of connective tissue surrounding smooth muscle cells. The presence of EMA is associated with autoimmune disorders, particularly those involving the gastrointestinal tract.
**Why the Correct Answer is Right**
EMA is primarily used in the diagnosis of celiac disease, an autoimmune disorder characterized by a malabsorptive reaction to gluten. The immune system's response to gluten leads to the production of EMA, which can be detected in the serum or intestinal mucosa of affected individuals. The binding of EMA to the endomysium disrupts the normal functioning of smooth muscle cells, contributing to the symptoms of celiac disease.
**Why Each Wrong Option is Incorrect**
**Option A:** EMA is not typically used for diagnosing Crohn's disease, although it may be present in some cases due to the overlap between Crohn's and celiac disease. The primary diagnostic marker for Crohn's disease is the presence of granulomas.
**Option B:** EMA is not a marker for autoimmune hepatitis. The primary diagnostic markers for autoimmune hepatitis include the presence of anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (ASMA), and anti-liver kidney microsomal type 1 antibodies (anti-LKM-1).
**Option C:** EMA is not typically used for diagnosing ulcerative colitis. The primary diagnostic markers for ulcerative colitis include the presence of ANA, ASMA, and the presence of granulocytes in the colonic mucosa.
**Clinical Pearl / High-Yield Fact**
The presence of EMA is highly specific for celiac disease, but its sensitivity is lower in patients with mild or latent celiac disease. A positive EMA result should be confirmed with a biopsy showing villous atrophy and an increase in intraepithelial lymphocytes.
**Correct Answer: C. Celiac disease.**