Primary biliary cholangitis (PBC) is an autoimmune condition characterised by progressive destruction of intrahepatic bile ducts. The hallmark autoantibody is directed against which antigen?

• A Smooth muscle actin (anti-SMA)
• B Double-stranded DNA (anti-dsDNA)
• C Nuclear envelope proteins (anti-SP100 and anti-GP210)
• D E2 subunit of the pyruvate dehydrogenase complex (PDC-E2) — anti-mitochondrial antibody M2 ✓

Explanation

Anti-mitochondrial antibody (AMA) targeting the lipoyl domain of PDC-E2 is present in >95% of PBC patients and is the specific serological marker. Anti-SP100 and anti-GP210 are ANA subtypes that also occur in PBC (especially in AMA-negative cases), but AMA-M2 remains the hallmark. Anti-SMA is seen in autoimmune hepatitis type 1; anti-dsDNA in SLE.

Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.