Why does MG happen?

What triggers Myasthenia Gravis?

MG is a rare autoimmune disease that causes muscle weakness.(1) Put simply, your body’s natural defences are not working the way they’re supposed to.

It often shows up in the face first, with drooping eyelids being an early sign. Weakened eye muscles can also lead to double or blurred vision .

Smiling, chewing and breathing can also be affected. (1,2)

Autoimmune diseases in a nutshell

 

Autoimmune diseases occur when the immune system attacks the body's own components. These conditions are not contagious. Some people have an inherited predisposition, but in many cases the causes are still largely unknown.

What causes MG?

Myasthenia gravis (MG) occurs when the immune system mistakenly attacks the neuromuscular junction, where nerves and muscles communicate (3).

This attack disrupts the normal transmission of messages from nerves to muscles (3-5). As a result, the muscles can’t work as they’re supposed to.

 The neuromuscular junction without MG 

Without MG, the neuromuscular junction functions smoothly as the interface where a nerve communicates with a muscle to initiate movement. 

Here is how it works: the brain uses the nerve to send messages called acetylcholine (ACh), a crucial neurotransmitter.

These messages travel across the neuromuscular junction to reach the muscle, which receives them via acetylcholine receptors (AChR) (2).

 The neuromuscular junction with MG 

In the context of MG, the immune system generates specific antibodies known as immunoglobulins (Ig). These antibodies, which the immune system produces to fight infection and disease, include five types. Immunoglobulin G (IgG) is the most prevalent type and is particularly implicated in MG. 

In individuals with anti-AChR antibody positive generalized myasthenia gravis (gMG), these IgG antibodies mistakenly bind to AChR, disrupting their function and leading to characteristic MG symptoms (5-6).

Indeed, when harmful AChR antibodies attach to AChR, they block, damage, or destroy the AChR, which interrupts nerve-muscle communication. 

This prevents the muscles from getting some of the messages sent by the nerves, leading to MG symptoms.(7) ​

 IgG antibody and harmful AChR antibody 

In anti-AChR antibody positive gMG, the immune system accidentally creates antibodies called harmful AChR antibodies that attach to the AChR in the neuromuscular junction. MG symptoms occur when these harmful AChR antibodies attach to AChR.(6)

While there is no cure, MG symptoms can be treated

 

Even with MG, people can live happy and productive lives. There is much to learn and many challenges to navigate. And that's exactly what MG United offers: a community for information, support, and shared experiences.

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The 6 types of MG

 

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How is MG diagnosed?​

 

Diagnosing MG involves a thorough assessment by healthcare professionals. Explore the nuances of MG diagnosis and the main symptoms that can reveal it.​

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Explain MG to others

 

Understanding the fluctuating nature of MG can be difficult for your close relatives. Discover our practical tips for explaining what MG is and its impact on daily life.​

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Initiate the conversation with your doctor

Living with myasthenia gravis shouldn't stop you from doing the things you love. By talking to your healthcare professional, you can find a management plan that is tailored to your personal goals.

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REFERENCES :

1. Douglas Harper. Myasthenia. Online Etymology Dictionary. https://www.etymonline.com/word/myasthenia. Accessed May 2020.

2. Douglas Harper. Gravid. Online Etymology Dictionary. https://www.etymonline.com/search?q=gravis. Accessed May 2020

3. Howard JF. Clinical Overview of MG, MGFA. 2015. https://myasthenia.org/Professionals/Clinical-Overview-of-MG. Accessed Feb 2022. Deymeer F. Acta Myol. 2020;39:345-352

4. Nair, et al. Indian J Ophthalmol. 2014;62:985-991

5. Gilhus N. Front Neurol. 2020;554(11):1-6.

6. Sanders DB, Wolfe GI, Benatar M, Evoli A, Gilhus NE, Illa I, et al. International consensus guidance for management of Myasthenia Gravis: Executive summary. Neurology. 2016;87(4):419-25.

7. Hehir MK, et al. Neurol Clin. 2018;36(2):253-260.

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argenx, a global immunology company, created MG United to support people living with MG and those who care for them. By providing information on MG United, argenx aims to help improve the lives of people suffering from this autoimmune disease. MG United does not offer medical advice; always consult your healthcare team for personalized medical guidance. The brands listed are the trademarks of their respective owners.