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Pathogenesis of myasthenia gravis

Shawn J Bird, MD
Section Editors
Jeremy M Shefner, MD, PhD
Ira N Targoff, MD
Deputy Editor
John F Dashe, MD, PhD


Myasthenia gravis is an autoimmune disorder characterized by weakness and fatigability of skeletal muscles. Muscle weakness due to dysfunction of the neuromuscular junction (myasthenia) may be an acquired disorder. The vast majority of patients who develop myasthenia in adolescence or adulthood have autoantibodies that play a pathogenetically important role by attacking the acetylcholine receptor (AChR), fixing complement, and reducing the number of AChRs over time. These autoantibodies are thought to originate in hyperplastic germinal centers in the thymus where myoid cells expressing AChR are clustered. Such antibody-mediated disease is referred to as myasthenia gravis.

Similar weakness can also result from mutation of components of the neuromuscular junction, resulting in a group of disorders collectively referred to as "congenital myasthenia." This type of myasthenia is often appreciated at birth. Congenital myasthenia and weakness in newborns that is due to transplacental passage of antibodies from a pregnant woman with myasthenia gravis are presented separately. (See "Neuromuscular junction disorders in newborns and infants".)

The pathogenesis of myasthenia gravis is discussed in this topic review. Other aspects of this disorder are discussed separately. (See "Clinical manifestations of myasthenia gravis" and "Diagnosis of myasthenia gravis" and "Treatment of myasthenia gravis".)


Myasthenia gravis is a condition that fulfills all the major criteria for a disorder mediated by autoantibodies against the acetylcholine receptor (AChR) [1,2]:

The autoantibodies are present in 80 to 90 percent of affected patients

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Literature review current through: Oct 2017. | This topic last updated: Sep 20, 2016.
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