When it comes to muscular diseases, most of us have heard of especially common ones like muscular dystrophy and Lou Gehrig's disease. But one of the rarest muscular disorders is also one of the most ...

Myasthenia gravis, or MG, is "a chronic autoimmune neuromuscular disorder that causes muscle weakness and fatigue," says Hesterlee. It occurs "when a person’s immune system is essentially attacking ...