Myasthenia Gravis (MG)

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MedlinePlus Genetics: ⁴² Myasthenia gravis is a disorder that causes weakness of the skeletal muscles, which are muscles that the body uses for movement. The weakness most often starts in the muscles around the eyes, causing drooping of the eyelids (ptosis) and difficulty coordinating eye movements, which results in blurred or double vision. In a form of the disorder called ocular myasthenia, the weakness remains confined to the eye muscles. In most people with myasthenia gravis, however, additional muscles in the face and neck are affected. Affected individuals may have unusual facial expressions, difficulty holding up the head, speech impairment (dysarthria), and chewing and swallowing problems (dysphagia) that may lead to choking, gagging, or drooling.Other muscles in the body are also affected in some people with myasthenia gravis. The muscles of the arms and legs may be involved, causing affected individuals to have changes in their gait or trouble with lifting objects, rising from a seated position, or climbing stairs. The muscle weakness tends to fluctuate over time; it typically worsens with activity and improves with rest.Weakness of the muscles in the chest wall and the muscle that separates the abdomen from the chest cavity (the diaphragm) can cause breathing problems in some people with myasthenia gravis. About 10 percent of people with this disorder experience a potentially life-threatening complication in which these respiratory muscles weaken to the point that breathing is dangerously impaired, and the affected individual requires ventilation assistance. This respiratory failure, called a myasthenic crisis, may be triggered by stresses such as infections or reactions to medications.People can develop myasthenia gravis at any age. For reasons that are unknown, it is most commonly diagnosed in women younger than age 40 and men older than age 60. It is uncommon in children, but some infants born to women with myasthenia gravis show signs and symptoms of the disorder for the first few days or weeks of life. This temporary occurrence of symptoms is called transient neonatal myasthenia gravis.

MalaCards based summary: Myasthenia Gravis, also known as mg, is related to neonatal myasthenia gravis and myasthenic syndrome, congenital, 6, presynaptic, and has symptoms including ptosis, diplopia and dysarthria. An important gene associated with Myasthenia Gravis is AKAP12 (A-Kinase Anchoring Protein 12), and among its related pathways/superpathways are Overview of interferons-mediated signaling pathway and NF-kappaB Signaling. The drugs Bromides and Antimetabolites have been mentioned in the context of this disorder. Affiliated tissues include thymus, eye and skeletal muscle, and related phenotypes are ptosis and diplopia

MedlinePlus: ⁴¹ Myasthenia gravis is a disease that causes weakness in your voluntary muscles. These are the muscles that you control. For example, you may have weakness in the muscles for eye movement, facial expressions, and swallowing. You can also have weakness in other muscles. This weakness gets worse with activity, and better with rest. Myasthenia gravis is an autoimmune disease. Your body's immune system makes antibodies that block or change some of the nerve signals to your muscles. This makes your muscles weaker. Other conditions can cause muscle weakness, so myasthenia gravis can be hard to diagnose. Tests used to make a diagnosis include blood, nerve, muscle, and imaging tests. With treatment, the muscle weakness often gets much better. Medicines can help improve nerve-to-muscle messages and make muscles stronger. Other drugs keep your body from making so many abnormal antibodies. These medicines can have major side effects, so they should be used carefully. There are also treatments which filter abnormal antibodies from the blood or add healthy antibodies from donated blood. Sometimes, surgery to take out the thymus gland helps. Some people with myasthenia gravis go into remission. This means that they do not have symptoms. The remission is usually temporary, but sometimes it can be permanent. NIH: National Institute of Neurological Disorders and Stroke

NINDS: ⁵² Myasthenia gravis is a chronic autoimmune neuromuscular disease characterized by varying degrees of weakness of the skeletal muscles of the body, which are responsble for breathing and moving parts of the body, including the arms and legs. In myasthenia gravis, the immune system--which normally protects the body from foreign organisms--mistakenly attacks itself.   Symptoms vary in type and intensity, and may include: • muscle weakness in the arms, hands, fingers, legs and neck • weakness of the eye muscles • drooping eyelid • difficulty swallowing • shortness of breath • impaired speaking Myasthenia gravis is caused by an error in the transmission of nerve impulses to muscles. Antibodies (immune proteins produced by the body's immune system) block the normal activity of the neurotransmitter acetylcholine, which prevents muscles from contracting. The thymus gland also may give incorrect instructions to immune cells and cause the immune system to attack its own cells and tissues. .

OMIM®: ⁵⁷ Myasthenia gravis is an autoimmune disease in which antibodies bind to acetylcholine receptors or to functionally related molecules in the postsynaptic membrane at the neuromuscular junction. The antibodies induce weakness of skeletal muscles, which is the sole disease manifestation. The weakness can be generalized or localized, is more proximal than distal, and nearly always includes eye muscles, with diplopia and ptosis. The pattern of involvement is usually symmetric, apart from the eye involvement, which is often markedly asymmetric and involves several eye muscles. The weakness typically increases with exercise and repetitive muscle use (fatigue) and varies over the course of a day and from day to day, often with nearly normal muscle strength in the morning (summary by Gilhus, 2016). (254200) (Updated 08-Dec-2022)

GARD: ¹⁹ Myasthenia gravis (MG) is a chronic autoimmune neuromuscular disease characterized by weakness of the skeletal muscles. Common symptoms include weakness of the muscles that control the eye and eyelid, facial expressions, chewing, talking, and swallowing. Weakness tends to increase during periods of activity and improve after periods of rest. The condition results from a defect in the transmission of nerve impulses to muscles, which is due to the presence of antibodies against acetylcholine. The exact reason this occurs is not known. Some cases have been linked to tumors in the thymus gland. Some cases may go into remission temporarily, and muscle weakness may disappear so that medications can be discontinued.

Disease Ontology: ¹¹ An autoimmune disease of the nervous system that has material basis in antibodies to acetylcholine receptors at the neuromuscular junction, has symptom ptosis, has symptom diplopia, has symptom dysphagia, has symptom dysarthria, has symptom muscle weakness and has symptom shortness of breath.

Orphanet: ⁵⁸ Myasthenia gravis (MG) is a rare, clinically heterogeneous, autoimmune disorder of the neuromuscular junction characterized by fatigable weakness of voluntary muscles.

Wikipedia: ⁷⁵ Myasthenia gravis (MG) is a long-term neuromuscular junction disease that leads to varying degrees of... more...

Clinical features from OMIM®:

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