Antimitochondrial antibodies subtypes – a view beyond primary biliary cholangitis
Medical Review (Med. pregled), 2026, 62(1), 19-25.
E. Vikentieva1,2, T. Asenova2
1Laboratory of Clinical Immunology, Military Medical Academy – Sofia
2Department of Immunology, Medical diagnostic laboratory „Cibalab“ – Sofia
Abstract: Anti-mitochondrial antibodies (AMA) are autoantibodies directed against the subu-nit of the pyruvate dehydrogenase multienzyme complex (PDC-E2), an epithelial-specific autoantigen found in patients with primary biliary cholangitis (PBC). Although they are a highly specific marker for PBC (found in 90–95% of patients), AMA can also be detected in about 1% of healthy individuals without any signs of hepatobiliary disease, and the data regarding the clinical risk of developing PBC in these cases remain controversial. At present, nine AMA subtypes have been de-scribed based on antigenic specificity (M1–M9). AMA-M2 are strongly associated with PBC, although they can also be found in other conditions such as rheumatoid arthritis, systemic sclerosis, Sjögren disease, and, in rare cases, in active chronic autoimmune hepatitis. Subtypes M4, M8, and M9 have also been linked to PBC, although M4 and M8 are considered likely artefacts of the detection methods. In contrast, AMA-M9 is regarded as a marker of PBC even in the absence of AMA-M2. Subtypes M1, M3, M5, M6, and M7 have also been detected in antiphospholipid syndrome, syphilis, phenopyrazone-induced pseudolupus syndrome, various collagenoses (including systemic lupus erythematosus and mixed connective tissue disease), autoimmune hemolytic anemia, isoniazid-induced hepatitis, cardiomyopathy (including dilated cardiomyopathy), and myocarditis.
Key words: antimitochondrial antibodies, subtypes, clinical association
Address for correspondence: Elena Vikentieva, M.D., Ph.D., e-mail: elivikentieva@gmail.com