Which antibody is commonly associated with primary biliary cholangitis?

• A. Antimitochondrial antibodies
• B. Anti-smooth muscle antibodies
• C. ANA
• D. Anti-dsDNA

Answer: (A)

In primary biliary cholangitis, the most characteristic serologic finding is antimitochondrial antibodies. These antibodies are positive in the vast majority of patients (roughly 90–95%) and point toward autoimmune destruction of the small intrahepatic bile ducts, which defines the disease. The antibodies target components of the mitochondrial pyruvate dehydrogenase complex, especially the E2 subunit, making this marker highly consistent with PBC.

Other antibodies can appear in autoimmune liver and connective tissue diseases, but they’re less specific for this condition. Anti-smooth muscle antibodies are more typical of autoimmune hepatitis. ANA can be present in PBC but isn’t as specific, and anti-dsDNA is associated with systemic lupus erythematosus, not PBC. Therefore, antimitochondrial antibodies best identify primary biliary cholangitis.