Myasthenia gravis, also known as MG, is a neuromuscular autoimmune disease that weakens the muscles. An autoimmune disease is caused by a failure of the body's immune system that causes it to mistakenly attack healthy tissue and produce so many antibodies (substances that recognize and fight infections and other foreign things in the body) that the healthy tissue is damaged.
MG is caused by a defect in the neuromuscular junction, which is where nerve connects with muscle. It is the most common neuromuscular junction disorder. MG generally causes weakness in the muscles that control the eyelids and can also cause muscle pain throughout the body. In extreme cases, the patient may become unable to breathe without a respirator.
While there is not yet a cure for MG, most patients can show significant improvement with the proper treatment and can expect to lead normal lives.