Myasthenia Gravis is an autoimmune condition where the body’s immune system damages the receptors that conduct the signals from nerves to muscles. Consequently, the muscle’s response to repeated nerve signals declines, leading to weakness and fatigue. The muscle weakness often first appears in the muscles of the face, neck and jaw. The arm and leg muscles are affected at a later stage. Myasthenia gravis affects about 100 per million people. Women under age of 40 and men over 60 are most commonly affected.