Skip to
  1. Homepage
  2. Rare diseases
  3. Search
Simple search

Simple search

*
(*) mandatory field





 

Other search option(s)

Myasthenia gravis

ORPHA589
Synonym(s) Acquired myasthenia
Autoimmune myasthenia gravis
Prevalence 1-5 / 10 000
Inheritance Not applicable
Age of onset All ages
ICD-10
  • G70.0
OMIM
UMLS
  • C0026896
MeSH
  • D009157
MedDRA
  • 10028417

Summary

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

The prevalence is estimated to be 1/5,000 and the incidence 1/250,000 to 1/33,000 in Europe. MG affects both males and females: mainly females before the age of 40 years and equally males and females after 50 years of age.

Myasthenia gravis can develop at any age but there is a bimodal peak in age of onset in the adult-onset form, with primarily female patients before 40 years of age, and primarily males after 50 years of age (Adult-onset myasthenia gravis; see this term). Patients have fluctuating weakness worsening with repetitive activities, heat, stress improving with rest with involvement skeletal muscle groups of ocular, bulbar, extremities and neck. Ocular manifestations include fluctuating diplopia and ptosis. Bulbar involvement may be found with fatigable chewing, dysphagia and dysarthria and some patients develop generalized muscle weakness, which may become serious with respiratory muscle weakness. In the juvenile form, onset is before 18 years of age (juvenile myasthenia gravis; see this term) and patients also present ocular and possibly generalized muscle weakness. A transient neonatal form causing hypotonia and feeding difficulties occurs in some newborns born to mothers with MG (transient neonatal myasthenia gravis; see this term). Congenital genetic forms of MG with a different pathogenesis also occur (congenital myasthenic syndromes, see this term).

The exact pathogenesis is not known but MG is related to circulating antibodies to various muscle receptors, including acetylcholine receptor (AChR) and muscle-specific receptor tyrosine kinase (MuSK). Another target, the low density lipoprotein receptor-related protein 4 (LRP4), has been also described. The thymus is thought to trigger antibody production in the form with anti-AChR antibodies. These antibodies have been found to play a pathogenic role in all the forms of the disease. The disorder can also be drug induced (D-penicillamine, interferon alpha, and bone marrow transplantation). An initial infection (EBV) may be responsible for some cases of MG. The role of infections has been strongly suggested by evidence of involvement of interferon type I in the disease, but direct evidence is lacking.

Expert reviewer(s)

  • Dr Sonia BERRIH-AKNIN
  • Pr Bruno EYMARD

(*) Required fields.

Attention: Only comments seeking to improve the quality and accuracy of information on the Orphanet website are accepted. For all other comments, please send your remarks via contact us. Only comments written in English can be processed.


Captcha image

Detailed information

Summary information
Emergency guidelines
  • DE (2010,pdf)
  • ES (2010,pdf)
  • EN (2010,pdf)
  • FR (2010,pdf)
  • IT (2013,pdf)
Anesthesia guidelines
  • EN (2014,pdf)
Review article
  • EN (2007)
Clinical practice guidelines
  • DE (2012)
  • EN (2010)Patient Inform
Article for general public
  • FR (2009,pdf)
Get Acrobat Reader
The documents contained in this web site are presented for information purposes only. The material is in no way intended to replace professional medical care by a qualified specialist and should not be used as a basis for diagnosis or treatment.