Myasthenia gravis (MG) is an autoimmune condition in which certain muscles become weak after use and then stronger again after rest. Between 36,000 and 60,000 people in the United States have been diagnosed with MG.1
While MG is the most common disorder of neuromuscular transmission, it is still a rare disease. Other autoimmune conditions like rheumatoid arthritis, lupus, and multiple sclerosis are much more common than MG. Unlike other autoimmune conditions, MG is equally common in men as women, though there are some differences in how the disease attacks each gender.1
Men
While MG can occur at any age, symptoms most often begin in men when they are in their 60s and 70s. MG that begins after age 50 is called late-onset MG. Late-onset MG is linked to changes in the HLA-DR2, HLA-B7, and HLA-DRB1 genes.2-4
Men are more likely to have ocular MG. Ocular MG is a form of the disease that attacks only the eye muscles and never spreads to other areas of the body. Also, men are less likely to have thymomas or respond to thymectomy as a treatment.2-4
Women
Symptoms of myasthenia gravis most often begin in women when they are in their 20s to 40s but can begin at any age. MG that begins before age 50 is called early-onset MG. MuSK MG and LRP4 MG are rare forms of myasthenia gravis that are more common in women than men.3,4
Women with MG need to work with their doctors ahead of time to plan their pregnancy and adjust their treatment plan to protect their unborn baby. Pregnancy impacts every woman with MG differently but generally does not increase the risk of birth problems. Still, women with MG should be followed closely by their obstetrician and neurologist. Symptoms may flare after birth due to the extra stress of changes to routine and caring for a baby.2-4
While many aspects of MG are similar between men and women, 1 study found that women’s quality of life was worse than men’s. The Myasthenia Gravis Foundation of America Patient Registry found that women had more:5
- Problems with daily activities
- Depression
- Fatigue
- Additional autoimmune conditions
The study also found that women’s quality of life improved more when they had a thymectomy than women who did not.5
Children
Myasthenia gravis is even rarer in children than it is in adults. Only about 1 in 10 people with MG are children or teens, and they most often develop symptoms between ages 7 and 14. However, babies born to women with MG may develop a temporary type of MG called neonatal myasthenia gravis. Juvenile MG is slightly more common in East Asians.1,4
Older adults
Older adults with MG are less likely to enter remission and have greater chances of side effects to treatment.1-4
Multiple autoimmune diseases
People with 1 autoimmune disease are more likely to develop a second or third autoimmune condition. About 1 out of 10 people with MG will have another autoimmune condition such as thyroiditis.1-4
This may be because some types of MG are linked to changes in genes that control the immune system including the HLA-DR3 and HLA-B8 genes. These genes are also linked to lupus, rheumatoid arthritis, and multiple sclerosis, which are more common autoimmune conditions.3,4