MG Basics

Myasthenia gravis (MG) is a rare autoimmune disease characterized by muscle weakness and fatigue.

If you’d like to find out a little nswers to some of the most frequently asked questions about MG.

Who can get MG?

MG can affect both men and women and even children of all ethnic groups. However, it mainly affects women below age 40 and men over age 60. 

What causes MG?

MG is caused by the immune system mistakenly attacking components of the neuromuscular junction, or the connection between nerve and muscle cells. The protein that is most often attacked in the acetylcholine receptor (AChR) to which acetylcholine, a chemical that carries electrical signals across the neuromuscular junction, binds. 

When the number of AChRs decreases due to the autoimmune attack, the signal from the nerve cells to the muscle cells is disrupted, leading to muscle weakness and fatigue.

How common is MG?

Around 150 to 200 out of every million people have MG globally. In the US, an estimated 37 people out of every 100,000 have MG

Is MG hereditary?

There is no known genetic mutation that is directly linked to MG, so the disease cannot be called hereditary and does not run in families.

However, there may be some genetic factors that make some people more susceptible to developing the disease, and 3 to 5% of people with MG also have another family member who is also affected by the disease.

What are the early signs of MG?

In most people, MG first affects the eyes and causes symptoms like droopy eyelids and double vision. Sometimes, the eyes are the only organs that are affected by the disease, in which case it is called ocular MG. 

How do doctors diagnose MG?

Doctors can run a number of tests to diagnose MG. These may include the ice pack test in which a doctor places a pouch filled with ice on top the eyes to see if this reduces the droopiness of the eyelids. Your doctor may also order blood tests to check for autoantibodies against AChR and other antibodies that are known to be involved in MG, repetitive nerve stimulation and single-fiber electromyography (EMG) tests to check for muscle fatigability, imaging tests like a computed tomography or magnetic resonace imaging to assess the thymus gland and the edrophonium (tensilon) test.

Are there any treatments?

MG is a treatable condition. The first-line treatment for the disease is pyridostigmine, which is a medicine that blocks the effect of the enzyme that breaks down acetylcholine, thereby increasing the amount of acetylcholine available at the neuromuscular junction to transmit nerve signals to the muscles.

Other treatments include steroids and immunosuppressants to dampen the effect of the immune system.

What is the prognosis like?

The symptoms of MG can be mild or severe and can vary greatly from one patient to the other. Usually, symptoms are most severe in the first three years after diagnosis and can be followed by periods of remission. Most people with MG live full and active lives with treatment.

Are there any support groups?

Many organizations can offer support for people affected by MG and their families, like the Myasthenia gravis Foundation of America, Myasthenia Gravis Association and Myasthenia Gravis Hope Foundation.