National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Myasthenia gravis

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.[1] The exact reason this occurs is not known. Some cases have been linked to tumors in the thymus gland.[2] Researchers believe that variations in certain genes may increase a person's risk to develop MG, but other factors likely also play a role.[3] There is no cure for MG at this time, but treatment can significantly improve muscle weakness. Some cases may go into remission temporarily, and muscle weakness may disappear so that medications can be discontinued.[1][2]
Last updated: 4/3/2018
Myasthenia gravis (MG) causes muscle weakness and can affect any voluntary muscle. Voluntary muscles are the muscles that we directly control to make our body do things like walk, run, write, throw, lift, smile, and chew. In MG, the most commonly affected muscles are the muscles that control eye and eyelid movement, facial expressions, and swallowing. The degree of muscle weakness varies from person to person. People with more severe disease may have many muscles affected, including the muscles that control breathing. People with mild disease may have only one muscle group involved, such as the eye muscles.[1]

In general, signs and symptoms of MG may include:[1]
  • Drooping of one or both eyelids (ptosis)
  • Blurred or double vision (diplopia)
  • Unstable or waddling gait (manner of walking)
  • Weakness in the arms, hands, fingers, legs, and neck
  • Change in facial expression
  • Difficulty swallowing and shortness of breath
  • Impaired speech (dysarthria)
People can develop MG at any age. For unknown reasons, 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 MG have signs and symptoms of the condition for the first few days or weeks of life. This temporary occurrence of symptoms is called transient neonatal myasthenia gravis.[3]
Last updated: 4/3/2018

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

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Medical Terms Other Names
Learn More:
HPO ID
30%-79% of people have these symptoms
Abnormality of the thymus 0000777
Acetylcholine receptor antibody positivity 0030208
Bulbar palsy 0001283
Diplopia
Double vision
0000651
Dysarthria
Difficulty articulating speech
0001260
Dysphagia
Poor swallowing
Swallowing difficulties
Swallowing difficulty
[ more ] 		0002015
Dyspnea
Trouble breathing
0002094
Muscle specific kinase antibody positivity 0030210
Myositis
Muscle inflammation
0100614
Ophthalmoparesis
Weakness of muscles controlling eye movement
0000597
Ptosis
Drooping upper eyelid
0000508
Single fiber EMG abnormality 0030006
5%-29% of people have these symptoms
Glycosuria
Glucose in urine
0003076
Hashimoto thyroiditis 0000872
Hearing impairment
Deafness
Hearing defect
[ more ] 		0000365
Hyperacusis 0010780
Hyperthyroidism
Overactive thyroid
0000836
Paresthesia
Pins and needles feeling
Tingling
[ more ] 		0003401
Primary adrenal insufficiency 0008207
Raynaud phenomenon 0030880
Rheumatoid arthritis 0001370
Systemic lupus erythematosus 0002725
1%-4% of people have these symptoms
Acrocyanosis
Persistent blue color of hands, feet, or parts of face
0001063
Hemolytic anemia 0001878
Hepatitis
Liver inflammation
0012115
Psychosis 0000709
Pure red cell aplasia 0012410
Seizure 0001250
Percent of people who have these symptoms is not available through HPO
Abnormality of the endocrine system 0000818
Abnormality of the immune system
Immunological abnormality
0002715
Autoimmunity
Autoimmune disease
Autoimmune disorder
[ more ] 		0002960
Facial palsy
Bell's palsy
0010628
Fatigable weakness 0003473
Impaired mastication
Chewing difficulties
Chewing difficulty
Difficulty chewing
[ more ] 		0005216
Limb muscle weakness
Limb weakness
0003690
Multifactorial inheritance 0001426
Nasal speech
Nasal voice
0001611
Proximal muscle weakness
Weakness in muscles of upper arms and upper legs
0003701
Thymoma 0100522
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Last updated: 7/1/2020
The exact cause of myasthenia gravis (MG) is unknown, but it is likely that a number of factors contribute to the risk of developing this disorder.[3]

MG is a type of autoimmune disorder. Autoimmune disorders occur when the immune system mistakenly attacks healthy tissue.[2] In MG, the body produces antibodies that block the muscle cells that receive messages (neurotransmitters) from the nerve cells.[2][1][3]

Normally when impulses travel down a nerve, the nerve endings release a neurotransmitter substance called acetylcholine. Acetylcholine travels from the neuromuscular junction - the place where nerve cells connect with the muscles they control -  and binds to acetylcholine receptors which are activated and generate a muscle contraction. In myasthenia gravis, antibodies block, alter, or destroy the receptors for acetylcholine at the neuromuscular junction, which prevents a muscle contraction from occurring. These antibodies are produced by the body's own immune system.[1] 

In some cases, MG is linked to tumors or other abnormalities of the thymus (a gland the plays an important role in the immune system).[2][1][3] Researchers also believe that variations in certain unidentified genes may increase the risk to develop MG.[3]
Last updated: 4/3/2018
Myasthenia gravis is not directly inherited, nor is it contagious.[4][5] However, a genetic predisposition to autoimmune disease can run in families.[5][3] Occasionally, myasthenia gravis may occur in more than one member of the same family.[4][3]
Last updated: 4/3/2018

The resources below provide information about treatment options for this condition. If you have questions about which treatment is right for you, talk to your healthcare professional.

Management Guidelines

  • Orphanet Emergency Guidelines is an article which is expert-authored and peer-reviewed that is intended to guide health care professionals in emergency situations involving this condition.  
  • Project OrphanAnesthesia is a project whose aim is to create peer-reviewed, readily accessible guidelines for patients with rare diseases and for the anesthesiologists caring for them. The project is a collaborative effort of the German Society of Anesthesiology and Intensive Care, Orphanet, the European Society of Pediatric Anesthesia, anesthetists and rare disease experts with the aim to contribute to patient safety.

FDA-Approved Treatments

The medication(s) listed below have been approved by the Food and Drug Administration (FDA) as orphan products for treatment of this condition. Learn more orphan products.

In the US, the estimated annual incidence of myasthenia gravis (number of newly diagnosed cases) has been reported as 1 in 500,000 people.[6] To our knowledge, estimates of prevalence (total number of cases that exist at a given time) in the US range considerably, from 1 in 2,500 to 1 in 200,000 people.[6][7][8] The prevalence appears to have risen over the past 2 decades, mostly due to earlier diagnosis and increased lifespan of affected people.

While myasthenia gravis can occur at any age, the female incidence is highest in the third decade of life, and the male incidence is highest in the sixth or seventh decade. The average age of onset is 28 years in females and 42 years in males.[6]
Last updated: 3/9/2016

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

  • ClinicalTrials.gov lists trials that are related to Myasthenia gravis. Click on the link to go to ClinicalTrials.gov to read descriptions of these studies.

    Please note: Studies listed on the ClinicalTrials.gov website are listed for informational purposes only; being listed does not reflect an endorsement by GARD or the NIH. We strongly recommend that you talk with a trusted healthcare provider before choosing to participate in any clinical study.

Patient Registry

  • The Autoimmune Registry supports research for Myasthenia gravis by collecting information about patients with this and other autoimmune diseases. You can join the registry to share your information with researchers and receive updates about participating in new research studies. Learn more about registries.
  • A registry supports research by collecting of information about patients that share something in common, such as being diagnosed with Myasthenia gravis. The type of data collected can vary from registry to registry and is based on the goals and purpose of that registry. Some registries collect contact information while others collect more detailed medical information. Learn more about registries.

    Registries for Myasthenia gravis:
     

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Organizations Supporting this Disease

Social Networking Websites

  • RareConnect has an online community for patients and families with this condition so they can connect with others and share their experiences living with a rare disease. The project is a joint collaboration between EURORDIS (European Rare Disease Organisation) and NORD (National Organization for Rare Disorders).

Organizations Providing General Support

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Community Resources

  • The Job Accommodation Network (JAN) has information on workplace accommodations and disability employment issues related to this condition. JAN is a service of the Office of Disability Employment Policy in the U.S. Department of Labor.

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

  • Genetics Home Reference (GHR) contains information on Myasthenia gravis. This website is maintained by the National Library of Medicine.
  • The Muscular Dystrophy Association provides additional information on myasthenia gravis. Click on the link to view this information page.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The National Institute of Neurological Disorders and Stroke (NINDS) collects and disseminates research information related to neurological disorders. Click on the link to view information on this topic.
  • The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

  • Medscape Reference provides information on this topic. You may need to register to view the medical textbook, but registration is free.
  • The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
  • Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss Myasthenia gravis. Click on the link to view a sample search on this topic.

Selected Full-Text Journal Articles

  • The Orphanet Journal of Rare Diseases has published an article with information on this condition. This journal is affiliated with the Orphanet reference portal for information on rare diseases and orphan drugs.

Questions sent to GARD may be posted here if the information could be helpful to others. We remove all identifying information when posting a question to protect your privacy. If you do not want your question posted, please let us know. Submit a new question

  • My husband recently had a heart attack, and he also has myasthenia gravis (MG). He has no family or personal history of coronary problems, he is in great physical condition. Could the MG have contributed or be a cause of his heart attack? See answer

  • My brother has been diagnosed with myasthenia gravis and I am wondering how rare this illness is. Have statistics been figured out? See answer

  • What does myasthenia gravis do to my body? See answer

  • Is myasthenia gravis genetic? See answer


  1. Myasthenia Gravis Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). July 27, 2015; http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm.
  2. Kantor D. Myasthenia gravis. MedlinePlus. June 1, 2015; https://www.nlm.nih.gov/medlineplus/ency/article/000712.htm.
  3. Myasthenia gravis. Genetics Home Reference (GHR). July 2012; http://ghr.nlm.nih.gov/condition/myasthenia-gravis.
  4. Myasthenia Gravis Fact Sheet. National Institute of Neurological Disorders and Stroke (NINDS). 2016; http://www.ninds.nih.gov/disorders/myasthenia_gravis/detail_myasthenia_gravis.htm.
  5. Myasthenia Gravis: Frequently Asked Questions. Myasthenia Gravis Foundation of America. 2010; http://www.myasthenia.org/WhatisMG/FAQs.aspx.
  6. Shah AK. Myasthenia Gravis. Medscape Reference. March 23 2016; http://emedicine.medscape.com/article/1171206-overview.
  7. Myasthenia Gravis. NORD. 2014; http://rarediseases.org/rare-diseases/myasthenia-gravis/.
  8. James F. Howard, Jr. Clinical Overview of MG. Myasthenia Gravis Foundation of America. 2015; http://www.myasthenia.org/HealthProfessionals/ClinicalOverviewofMG.aspx.