American Board of Internal Medicine (ABIM) Certification Practice Exam

What autoantibody is associated with autoimmune hepatitis?

1. Anti-Scl-70

2. Anti-U1 RNP

3. anti-smooth muscle

4. anti endomysial

The correct answer is: anti-smooth muscle

Autoimmune hepatitis is characterized by the presence of specific autoantibodies, and anti-smooth muscle antibodies are one of the hallmark markers for this condition. These antibodies target the smooth muscle fibers in the liver, indicating an autoimmune attack on liver cells. Patients with autoimmune hepatitis can present with symptoms of liver inflammation, including fatigue, jaundice, and elevated liver enzymes. The presence of anti-smooth muscle antibodies helps in the diagnosis and forms part of the support for an autoimmune etiology, particularly in individuals who may not display typical signs of viral hepatitis. In contrast, the other autoantibodies mentioned are associated with different autoimmune diseases. For example, anti-Scl-70 is related to systemic sclerosis, anti-U1 RNP is indicative of mixed connective tissue disease, and anti-endomysial antibodies are associated with celiac disease. These antibodies are not specifically implicated in autoimmune hepatitis, which further emphasizes the significance of anti-smooth muscle antibodies in the diagnosis of this liver condition.