Cause of myasthenia gravis: (A) Decreased release of Ach at NM junction, (B) Loss of muscles fibers, (C) Destruction of receptors by antibody, (D) Destruction of receptors by autolysis
Answer is C. Myasthenia gravis is rare autoimmune disease caused by the formation of circulating antibodies to the nicotinic A-ch receptors. These antibodies destroy some of the receptors and bind others to neighboring receptors. The disease is characterized by rapid onset of fatigue with marked generalized weakness of muscles. The most commonly affected muscles are: extraocular muscles, facial, swallowing and mastication muscles.Ref: Textbook of physiology, Dir. Prof. AK Jain, 5th edition.