Myasthenia gravis prevalence

Last updated Nov. 18, 2024, by Agate Boxe
Fact-checked by Patricia Silva, PhD

Myasthenia gravis (MG) is a rare neuromuscular disease that affects about 173 out of every million people worldwide and about 37 out of every 100,000 people in the U.S.

One of the most common causes of MG is a mistaken attack by autoantibodies that target acetylcholine receptors (AChRs), which are involved in nerve-muscle communication. When communication is disrupted, it can affect the muscles being able to contract, which often leads to MG symptoms such as muscle weakness and fatigue.

Both the MG prevalence, or the number of existing cases at a given time, and MG incidence, or the number of new cases diagnosed over a specific time period, seem to be on the rise. This may be due to better MG diagnosis techniques. Factors such as age, sex, and race can play a role in the disease’s onset, severity, and other related issues.

How many people have myasthenia gravis?

A 2024 review of previous research studies showed that globally, a mean 173 in a million people are living with MG. The researchers examined 94 studies conducted between 1952 and 2022.

An analysis of data from 2016 to 2021, published in 2023, found that about 37 in 100,000 people in the U.S. have MG.

According to both studies, the prevalence of MG increased with age.

Geographical differences

The prevalence of MG varies across the continents, with the highest numbers found in North America and the lowest in Asia.

• North America: a mean prevalence of 341 cases per million people
• South America: a mean of 150 per million
• Europe: a mean of 168 per million
• Asia: a mean of 127 per million.

More research is needed to determine how many people in Africa and Oceania have the disease.

It is not clear why North America seems to have the highest rates of MG. Potential explanations could be that there is more tracking of MG through national databases as well as genetic and environmental factors.

While Asia has the lowest overall prevalence of MG worldwide, it has the highest rates of juvenile MG, which is a type of MG that affects children and teens. The rate is nearly 46 cases per million compared with a mean of nearly 21 cases per million worldwide.

Differences by sex

Age plays a role in the relationship between sex and MG onset.

Early-onset MG is more common in women whereas late-onset MG more likely occurs in men. In people younger than 50, the prevalence and incidence of MG are typically higher among women than men. However, among people 65 years and older, the prevalence and incidence are higher for men than for women.

In terms of disease progression, women with MG tend to have more severe disease and poorer quality of life compared with men.

The gender differences may be related to the interaction between hormones and antibody production in MG. Women are also more likely to have thymic hyperplasia, which is an enlargement of the thymus gland that is linked to MG.

Differences by race and ethnicity

Race and ethnicity can play a role in MG prevalence, severity, and quality of care received.

In the U.S., African Americans are more likely to have MG, and many have antibodies against muscle-specific tyrosine kinase, which is a type of antibody that often causes the condition to be more severe. They also tend to have an earlier onset of the disease.

Research also reveals disparities in healthcare and MG treatment outcomes. For example, a 2024 study reported Black people with MG were less likely to receive steroids than people of other races who had the disease. The disparity may have something to do with biases contributing to undertreatment, such as those related to incorrectly perceived pain tolerance.

Another study, published in 2022, suggests Black people may have a higher risk of experiencing negative outcomes of MG-related hospitalization. These risks include infections affecting the entire body, renal failure, and blood clots that form within veins deep inside the body.

The same study showed Black, Hispanic, and Asian or Pacific Islander people with MG were more likely to require ventilator support. This may be due to delays in receiving care, which then leads to severe breathing issues requiring ventilation. The delay in care is thought to be associated with two main reasons: the fact that minority populations more often experience delays in receiving healthcare, and because they may seek medical care only when their symptoms are in an advanced stage.

Are rates of myasthenia gravis increasing?

The prevalence and incidence rates of MG, both in the U.S. and worldwide, appear to be on the rise. The exact reasons behind these increases are unclear.

The prevalence of MG in the U.S. is estimated to be 1.8 times higher than it was in the early 2000s and 2.6 times higher than it was in the early 1980s.

The incidence of MG in the U.S. was about 3 in 100,000 people in 2021. The incidence rate was three times higher than the estimates previously reported in 1992.

The 2024 review based on worldwide data yielded similar observations. The mean prevalence based on studies from 1952 to 2007 was 97.5 cases per million, while for studies from 2008 to 2021, it rose to about 220 per million.

The potential reasons behind these increases include greater life expectancy and the aging of the world’s populations. It is also possible that doctors now use better diagnostic tools, and epidemiologists have more effective ways to recognize cases of MG.

Myasthenia Gravis News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.