Is myasthenia gravis a rare disease, or is it just underdiagnosed?
A columnist turns to research and statistics for answers
Someone recently left a comment on one of my columns that made me pause and lean in. They wrote that myasthenia gravis (MG) isn’t rare; it’s just underdiagnosed.
Oofta. That one hit like a whisper with a punch. Because on the surface, it feels true. Many of us with MG waited years for a proper diagnosis and were often misread, dismissed, or misunderstood in the meantime. My own journey to diagnosis took seven years. So the idea that MG is just flying under the radar? Sure, it makes sense. But is that the whole story?
What does ‘rare’ even mean?
To figure out if MG is rare or not, we need to understand what’s considered a rare disease. As it turns out, the definition varies depending on where you are in the world.
- In the United States, a disease is considered rare if it affects fewer than 200,000 people.
- In Europe and the U.K., rare diseases are defined as affecting fewer than 1 in 2,000 people.
- In Australia, a condition is deemed rare if it affects 5 or fewer people per 10,000.
- The World Health Organization defines a rare condition as affecting fewer than 65 per 100,000 people.
So where does MG land?
According to one analysis, in 2021, MG was estimated to affect 37 in 100,000 people in the U.S. That definitely checks the “rare” box — but here’s where it gets juicy.
MG is a master of disguise. Its symptoms — including muscle weakness, droopy eyelids, slurred speech, and fatigue — can look like stroke, multiple sclerosis, depression, or even everyday exhaustion, among countless other conditions. That overlap means a lot of folks are misdiagnosed or simply never diagnosed at all. It’s especially tricky for those of us with seronegative MG, where the usual antibody tests come up clean.
So, yes, the numbers say it’s rare. But I think the real prevalence might be higher than what’s recorded.
Diagnosed more, but still hard to catch
What’s interesting is that, over the last few decades, the incidence and prevalence of MG have more than doubled. More accurate tests, increased awareness, and people living longer with MG have likely played a role. But that doesn’t necessarily mean that a higher proportion of people have it now; it could just mean that more of us are finally being seen and diagnosed. That distinction matters.
OK, but what if MG stops being rare in terms of numbers? Let’s say it tips over that threshold — what then?
Rare diseases tend to have several things in common, such as complex biology, specialized treatments, and limited research and resources. MG definitely checks those boxes!
Managing MG often requires a team of specialists, an individualized treatment plan, consistent monitoring, and frequent adjustments. The disease can be unpredictable, and many general practitioners may not feel confident treating it on their own. MG support, resources, and research are still relatively limited compared with more well-known chronic conditions.
Even if the prevalence rises to the point that MG is no longer considered rare, we’re still dealing with a complex condition that requires personalized care — something we’ll continue to have in common with much of the rare disease community.
So is MG rare? The bottom line is, technically, yes. But it’s also likely that the condition is underdiagnosed; it might not even be considered rare one day. Both can be true at the same time.
And to the person who dropped that comment — you’re not wrong. You just helped spark a deeper conversation. And for that, I’m grateful.
Note: 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. The opinions expressed in this column are not those of Myasthenia Gravis News or its parent company, Bionews, and are intended to spark discussion about issues pertaining to myasthenia gravis.
About the Author
William Pearson
My treatment hasn't been changed since I was first diagnosed on September 14th 2012. I very rarely see my consultant. I last saw her early 2024 and I can't see her again until February 2026. I am now in a wheelchair and cannot walk at all
Thomas Bartlett
I like your response to the comment. In science accurate numbers of validated diagnosed individuals is critical. These numbers affect so many aspects of how treatments are researched and patient programs are funded. As you noted, there is a high probability there are more people living with MG, however the number can't a feeling or a belief. It must be accurate based on the data collected. That research is so important to developing new methods to determine if MG is present. That world is changing every day. A new paper was presented this month by UCSD and Yale. They have developed a new method to "see" the presence of MG via an advanced imaging technology, Cryo-EM. This is very exciting news where there results of the imaging will help with future diagnosis's. It will, also, improve the creation of new targeted therapies, precision medicine, to better treat patients more succinctly. It's a very exciting time. https://today.ucsd.edu/story/advanced-imaging-reveals-mechanisms-that-cause-autoimmune-disease
Dee Harlow
As rare as MG is, both my husband and I came down with it in 2021 after being vaccinated for Covid. Our neurologist couldn’t believe it.
Barbara Bender
I was diagnosed 8 months ago with a blood test. Can't see a Neurologist until Aug 6, 2025. Thank goodness for Myasthenia Gravis News or I wouldn't know anything. Taking Pyridostigmine 60 mg. Helps with the double vision. My biggest problem is I'm 82 with many different medical problems, so I'm never sure if it's MG or something else. I have no one to talk to about this. No one talks about it because they're not sure it's a real disease! It reminds me of Fibromyalgia. Diagnosis was a process of elimination. I'm glad I found Myasthenia Gravis News. I'm gradually developing basic knowledge for myself.
micheline okazaki
I was diagnose with a stroke at urgent care after a battery of tesst. My symtoms: double vision, numbness mouth area; I was sent home with blood thinner, statins... The MRI/cat-scan wasn't conclusive. I beg my PCP for the MG blood test and 10 days later, I had MG. Amazing that cardiologists are not aware that MG has the same sypmtoms as a stroke.
Winston Roden
Shawna,
I agree with your statements even though I was lucky and was sent to a neurological ophthalmologist early on and she recognized it and was very surprised to see something so rarely seen in our area. She treated me for a month and then sent me to a neurologist because mine was generalized.
Donna Kobylakiewicz
Since I was diagnosed in 2023 after five years of going back-and-forth to doctors, I believe this is not that rare but very underdiagnosed. I think the doctors don’t really listen. I know mine was blamed more on age, what had happened in my life my husband‘s death, my parent’s death rather than my systems. I told every doctor and my words were this is a fatigue like I have never ever experienced. A woman can be tired, but they push themselves. This however was a fatigue where my body just gave out. Onced diagnosis, every specialist called me and on their own way apologized for missing it.
I had a medical tech and x ray license plus a daughter who was diagnosed at 2 years of age with diabetes so I do know how to track systems and advocate for myself. What I lost in the 5 years of going to specialist after specialist played havoc on my mental health. So glad this is being addressed.
Sharon Hawe
There's another possible measure of "rare" which is if few know about it, especially in the medical field, which creates challenges for diagnosing and managing MG. I've found that medical professionals have varying degrees of awareness of MG from none to a lot. MG has been around for a long time, so long that my 90 yr old uncle and aunt both recall it from their training but now medical professionals have so many more rare diseases and conditions to learn about. MG patients need to ensure that their medical professionals are aware of MG and do their diligence on how to manage MG, for example, for a recent surgery, my neurologist advised me to tell absolutely everyone I encountered that I have MG and there is an MG protocol. Thank goodness for that - the anesthesiologist was changed at the last minute and didn't notice MG way down on my record and he appreciated the reminder.