What is the role of anti- receptor (AChR) antibody testing in the evaluation of myasthenia gravis (MG)?

Updated: Aug 27, 2018
  • Author: Abbas Jowkar, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

The anti–acetylcholine receptor (AChR) antibody (Ab) test is reliable for diagnosing autoimmune myasthenia gravis (MG). It is highly specific (as high as 100%, according to Padua et al). [4] Results are positive in as many as 90% of patients who have generalized MG but in only 50-70% of those who have only ocular MG; thus false negatives are common in cases of purely ocular MG. However, these may be present at the NMJ, the site of disease pathology, and are causal, but may not be detectable in the serum at an early stage of disease. 

Anti-AChR antibodies are predominantly IgG1 and IgG3. They effectively activate complement, leading to the formation of the membrane attack complex resulting in damage to the NMJ in the form of simplification of postsynaptic junctional folds, removal of AChR from the membrane, and widening of the synaptic cleft.


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