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Coalition of Canada

What is MG?

Myasthenia gravis (MG) is a chronic autoimmune disorder that results in progressive weakness of ocular and skeletal muscles. In acquired MG, antibodies attack and destroy acetylcholine receptor sites (AChR) in the neuromuscular junction, preventing nerve impulses from reaching the muscles. This results in weakness and fatigue in the affected muscles.

In the inherited or congenital forms of myasthenia, a genetic mutation produces a flaw in the neuromuscular junction, which affects transmission of nerve impulses.

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The onset of MG may be sudden, with severe and generalized muscle weakness, but more often the early symptoms are subtle and variable, making it a difficult disorder to diagnose.