What is the role of antimitochondrial antibodies (AMAs) in the diagnosis of primary biliary cholangitis (PBC)?

Updated: Nov 08, 2017
  • Author: Nikolaos T Pyrsopoulos, MD, PhD, MBA, FACP, AGAF; Chief Editor: BS Anand, MD  more...
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Answer

The hallmark of PBC is the presence of antimitochondrial antibodies (AMAs) in serum. AMAs can be found in 90-95% of patients with PBC, and they have a specificity of 98% for this disease. Four AMA profiles occur:

  • Profile A: Positive for anti-M9 only

  • Profile B: Anti-M9 and/or anti-M2–positive by ELISA

  • Profile C: Anti-M2, anti-M4, and/or anti-M8–positive by ELISA

  • Profile D: Anti-M2, anti-M4, and/or anti-M8–positive by ELISA and complement-fixation test

Patients with profile A or B have a better disease course than patients with profile C or D.

Some patients have clinical, biochemical, and histologic features of PBC, but their sera are negative for AMA. The diagnosis of autoimmune cholangitis has been used for these patients.


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