In the US, the estimated annual incidence of myasthenia gravis (number of newly diagnosed cases) has been reported as 1 in 500,000 people. To our knowledge, estimates of prevalence (total number of cases that exist at a given time) in the US range considerably, from 1 in 2,500 to 1 in 200,000 people. The prevalence appears to have risen over the past 2 decades, mostly due to earlier diagnosis and increased lifespan of affected people.
While myasthenia gravis can occur at any age, the female incidence is highest in the third decade of life, and the male incidence is highest in the sixth or seventh decade. The average age of onset is 28 years in females and 42 years in males.
Last updated: 3/9/2016
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