If you’re living with myasthenia gravis (MG), you might not often meet others with the condition. This can make it feel like you’re alone in experiencing the symptoms of MG, a chronic autoimmune disease that causes muscle weakness. But in reality, myasthenia gravis may be more common than it seems.

Read on to discover how common this condition is in the United States and around the world.

How Common Is Myasthenia Gravis in the US?

Myasthenia gravis doesn’t affect everyone at equal rates. Some people are more likely than others to develop this condition. The study of who gets a particular disease and why is known as epidemiology. This field analyzes the distribution, causes, and risk factors of health conditions within specific populations.

When trying to understand this type of data, it’s helpful to know the difference between prevalence and incidence rates. Prevalence is the total number of people who have a disease at a given time. Incidence refers to the number of new cases diagnosed in a certain period.

In other words, the prevalence of myasthenia gravis refers to how many people currently have the condition, while the incidence of MG indicates how many people are diagnosed each year. Both rates help doctors and researchers understand the epidemiology of myasthenia gravis.

Researchers estimate that in the United States, between 75,000 and 100,000 people are living with myasthenia gravis. A 2024 study analyzing health insurance data from 30 million people who were on Medicare, commercial insurance, and Medicaid suggested that about 82,715 U.S. adults had MG in 2021.

Although it’s hard to get exact numbers, a study reviewing medical records from more than 300 million people in the U.S. from 2011 to 2021 suggested that about 3.2 new MG cases are diagnosed per 100,000 people each year. In total, about 37 out of every 100,000 people in the USA have myasthenia gravis.

What Are the Global Occurrence Rates of Myasthenia Gravis?

Prevalence rates for myasthenia gravis worldwide are estimated to be 150 to 200 cases per million people. However, this number may be lower than the true rate, because tracking myasthenia gravis can be challenging in some regions. Research suggests that prevalence of MG is higher in North America than in other parts of the world.

A 2024 study found the following MG prevalence rates per million people:

• North America — 341.4
• South America — 149.8
• Europe — 167.9
• Asia — 127.4

One reason myasthenia gravis seems more common in North America could be improved reporting methods. Doctors in North America may have more advanced tools for recording and sharing information about MG cases. This could make it look like more cases occur there, even if the actual number isn’t much different from that of other regions. The study authors suggested that the use of national databases may be more common in North America, leading to higher reported prevalence rather than a true difference in disease rates compared with other parts of the world.

Other factors could also play a role in MG prevalence. Research suggests that race and ethnicity may influence when myasthenia gravis develops and how it progresses. For example, a 2021 study in the Journal of Medicine and Life reported that African American women may have a higher incidence of MG compared to Caucasian women and to men of both racial groups. The authors noted this could be due to a higher risk of autoimmune diseases in Black populations.

Who’s More Likely To Get Myasthenia Gravis?

Myasthenia gravis isn’t inherited or contagious. The condition develops when the body’s immune system mistakenly attacks the connection between nerves and muscles. This attack creates autoantibodies that block muscle receptors, preventing muscles from responding properly to nerve signals. As a result, muscles get weaker.

Although myasthenia gravis can affect people in every age group, some may be at higher risk. These factors may increase the chances of developing MG:

• Being a man between ages 60 and 70 (as noted by the University of Maryland Medical System)
• Being a woman in her 20s or 30s
• Having certain genetic markers, such as HLA-B8 or DR3
• Having a thymoma (a tumor on the thymus gland, a small gland in the chest that helps regulate the immune system)

In addition, a condition called temporary or neonatal myasthenia gravis can occur when MG-related antibodies pass from the mother to the baby during pregnancy. This may cause muscle weakness in the infant for a short time, but symptoms usually go away within two months as the antibodies leave the baby’s body.

Are More People Developing Myasthenia Gravis?

Myasthenia gravis is being diagnosed more often across the world. One study found that the prevalence and incidence rates of MG were more than twice as high in 2024 than in 2010. But the increased prevalence and incidence rates don’t necessarily mean that myasthenia gravis is becoming more common. Instead, the increase could be due to improved awareness, better diagnosis of MG, and more accurate reporting. More research is needed to determine whether myasthenia gravis is truly on the rise or if doctors are simply getting better at identifying it.

In some cases, myasthenia gravis is misdiagnosed because its symptoms overlap with those of other conditions. “I’m 69 and was just diagnosed in 2023 after being misdiagnosed for about three or four years,” one MGteam member wrote. Another said, “I was diagnosed about two years ago after almost two prior years of being misdiagnosed.”

The growing awareness of myasthenia gravis may be helping more healthcare providers recognize the condition. “I think doctors are realizing MG is more common than they thought,” one MGteam member wrote. “The younger neurologists appear more aware of this disease and misdiagnosis.”

If you think you or a loved one might be experiencing myasthenia gravis symptoms, such as muscle weakness or eye problems, reach out to your primary care doctor or a neurology specialist (a doctor who focuses on brain, nerve, and muscle disorders). They can evaluate your symptoms, determine whether you have this autoimmune disorder, and create a treatment plan to help maintain your quality of life.

Find Your Team

On MGteam, the social network for people living with myasthenia gravis and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with MG.

What questions do you have about myasthenia gravis prevalence? Are you surprised to read about the higher incidence rates in recent years? Share your experience in the comments below, or start a conversation by posting on your Activities page.