Myasthenia Gravis: An inheritable disorder or an acquired auto-immune response Research in Allied Health Jeri Frazier November 1, 2005

A Rare Disease Myasthenia Gravis is considered a rare disease which often goes undiagnosed, overlooked or misdiagnosed. At the onset of the disease, MG is difficult to distinguish from other muscular diseases and myopathies because the symptoms are similar. A myasthenia gravis patient often presents with fatigue and weakened muscles. The general complaints may lead to the physician dismissing the symptoms completely. While considered rare, MG is the most common disorder of neurotransmission. Myasthenia Gravis is considered a rare disease which often goes undiagnosed, overlooked or misdiagnosed. At the onset of the disease, MG is difficult to distinguish from other muscular diseases and myopathies because the symptoms are similar. A myasthenia gravis patient often presents with fatigue and weakened muscles. The general complaints may lead to the physician dismissing the symptoms completely. While considered rare, MG is the most common disorder of neurotransmission.

Who MG Affects Muscular disease generally affects people equally of all ages. Gender plays a role in MG and the ages it affects. There is a female predominance among Caucasian patients under the age of 40, 3:1 ratio, termed early onset MG. Over the age of 60, MG is slightly more prevalent in men, 3:2 ratios, termed late onset MG. Late onset myasthenia gravis occurs within a population more frequently than early onset myasthenia gravis by a small percentage. Muscular disease generally affects people equally of all ages. Gender plays a role in MG and the ages it affects. There is a female predominance among Caucasian patients under the age of 40, 3:1 ratio, termed early onset MG. Over the age of 60, MG is slightly more prevalent in men, 3:2 ratios, termed late onset MG. Late onset myasthenia gravis occurs within a population more frequently than early onset myasthenia gravis by a small percentage.

An Autoimmune Disorder Myasthenia gravis is a chronic auto- immune disorder. Most often, it is a condition caused by antibodies produced against the acetylcholine receptor at the neuromuscular junction. These antibodies prevent signal transmission for the skeletal muscles by altering or destroying the receptor thus, preventing muscular contraction. Myasthenia gravis is a chronic auto- immune disorder. Most often, it is a condition caused by antibodies produced against the acetylcholine receptor at the neuromuscular junction. These antibodies prevent signal transmission for the skeletal muscles by altering or destroying the receptor thus, preventing muscular contraction.

Thymic Involvement The thymus gland is suspected of causing the auto-immune response in MG. When tested, 75% of MG patients have a thymic abnormality (thymic hyperplasia is the most common) and 15% of these patients have a thymoma. The thymus gland is the central organ for immunological self- tolerance. Scientists are uncertain whether the role of the thymus is primary or secondary to the disease. The thymus gland is suspected of causing the auto-immune response in MG. When tested, 75% of MG patients have a thymic abnormality (thymic hyperplasia is the most common) and 15% of these patients have a thymoma. The thymus gland is the central organ for immunological self- tolerance. Scientists are uncertain whether the role of the thymus is primary or secondary to the disease.

An Acquired Disorder Most auto-immune disorders are inherited and can be linked to a specific gene. Many people with an auto- immune response experience more than one self- mediated disorder. Unlike the other conditions, myasthenia gravis has not been proven to be inheritable. MG is thought to be an acquired response without genetic causes. Researchers are investigating the possibility of an inheritable link by studying HLA antigens as a possible source. The method of a gene defect triggering the autoimmune response is still unconfirmed but offers hope for those studying the disease. Most auto-immune disorders are inherited and can be linked to a specific gene. Many people with an auto- immune response experience more than one self- mediated disorder. Unlike the other conditions, myasthenia gravis has not been proven to be inheritable. MG is thought to be an acquired response without genetic causes. Researchers are investigating the possibility of an inheritable link by studying HLA antigens as a possible source. The method of a gene defect triggering the autoimmune response is still unconfirmed but offers hope for those studying the disease.