Myasthenia Gravis Risk Factors: Who Is Most Likely Affected?

Common myasthenia gravis (MG) risk factors are older age for men, younger age for women, and exposure to triggers. 

Myasthenia gravis is a long-term autoimmune disorder. It causes weakness in the muscles you use for movement. This results when your nerves don’t communicate with your muscles as they should. 
Symptoms include drooping eyelids, double or blurred vision, and problems with swallowing, chewing, and speaking. Though there’s usually no cure, treatment can help improve symptoms.  

What Causes Myasthenia Gravis?

The exact cause of myasthenia gravis is unknown. However, health experts believe specific genetic changes may make you more susceptible. 
In myasthenia gravis, your immune system produces proteins (antibodies) that disrupt the communication between your nerves and muscles. Why this happens is not well understood. 
Several studies have linked MG with thymoma (a rare tumor that forms on your thymus). That said, researchers do not yet know if thymoma causes MG.  

What Are the Major Myasthenia Gravis Risk Factors?

The major MG risk factors include:

Age

Anyone can get MG, regardless of their age. However, women between 20 and 39 and men between 50 and 70 are more likely to develop this condition [1].

Gender

Like other autoimmune disorders, generalized myasthenia gravis affects more women than men. The female-to-male ratio of MG patients is about 2:1 [2].
Some women may experience their first symptoms during pregnancy. Many women report a worsening of symptoms before their menstrual cycle. 

Thyroid and Other Diseases

Having thyroid disease may make you more likely to develop MG. About 5% to 10% of people with MG have thyroid disease [3]. 
In rare cases, the following autoimmune disorders may raise your risk of myasthenia gravis:

• Rheumatoid arthritis (RA)
• Systemic lupus erythematosus (SLE)

MG Risk Factors: Decoding the Role of Genetics

Genetic changes are thought to increase the risk of MG. However, these genes haven’t been identified yet. 
Moreover, MG is not typically inherited and can occur in those with no family history. A family history of MG or other autoimmune conditions is present in only about 4% of the cases [4].
Rarely, children born to affected mothers get MG. This is known as neonatal myasthenia gravis. Neonatal MG is temporary. With appropriate treatment, complete recovery occurs within 60 days after birth. 
Congenital myasthenic syndrome is a rare genetic condition that is similar to MG that is present in children at birth, although symptoms may not show until adulthood. Congenital myasthenic syndrome is not an autoimmune condition, and the treatment course is different from myasthenia gravis.  

Other Myasthenia Gravis Risk Factors

A 2023 study found a higher MG risk in people with type 2 diabetes, especially in women older than 50 [5]. This is a preliminary finding. Additional research is needed to establish a clear link. 

What Factors Can Make Myasthenia Gravis Worse?

If you have MG, the following factors can make your symptoms worse:

• Infection
• Immunization
• Surgery
• Drugs to treat malaria, seizures, and abnormal heart rhythms
• Stress

MG Risk Factors for Recurrence: What You Should Know

In some cases, the symptoms may reappear in people with MG who have had a thymectomy (surgery to remove the thymus). The risk is higher in [6]:

• Older adults
• Males 
• People with more severe disease

Death risk in MG patients may be higher if they have more severe symptoms, a stroke, diabetes, higher cholesterol levels, and abnormal heartbeats [7].
 

Myasthenic Crisis Risk Factors

Myasthenic crisis (MC) is a life-threatening complication of MG. It causes your breathing muscles to become too weak. You may need a breathing machine (ventilator) in severe cases. 
MC is more likely to occur if you have [8]:

• Severe symptoms at diagnosis
• Higher antibody levels
• Thymoma