The immune system of the body is to protect the body from foreign particles and organisms. As soon as the foreign particle enters the body, our immune system becomes active and destroys the particle or organism. Sometimes, the immune system functions abnormally leading to the attack on its own tissues and cells. The cells get damaged leading to disruption of physiological function. Myasthenia gravis is also an auto-immune disease.
How Does A Person Get Myasthenia Gravis?
Myasthenia gravis is the condition in which the muscles of the body become weak due to the problem in the immune system. Following are the causes of myasthenia gravis:
Autoimmune– Our immune system is the primary defense of the body. Whenever any foreign particles attack our body, the immune system gets activated and the foreign particle or organism gets killed by the synchronized function of the cells of the immune system. However, in some cases, the disease is caused due to the attack of the immune system on the body’s own healthy tissues and organs. The disease caused due to the damaging effect of the immune system is known as an autoimmune disease.
Myasthenia gravis is also an autoimmune disease. Various acetylcholine receptors are present at the neuromuscular junction. Acetylcholine is a neurotransmitter that helps in the effective functioning of the muscles by binding to its receptors. In myasthenia gravis, the immune system of the body attacks the receptors of acetylcholine, leading to a reduced number of sites for binding acetylcholine. It results in fewer nerve signals to contact and relax the muscles leading to muscle weakness. (1)
Genetics– Although a non-inherited disease, various researchers believe that the condition is caused due to variations in certain genes that trigger the attack of the immune system on acetylcholine receptors leading to myasthenia gravis. It has been found that in most of the case, myasthenia gravis occurs in families with no history of this condition. It has also been found that the gene mutation of the autoimmune characteristics may also increase the risk of other autoimmune diseases such as Systemic Lupus Erythematosus. (2)
Thymus Glands– Thymus gland is a part of the immune system and is also believed to the contributing factor for the development of myasthenia gravis. This is due to the fact that in not of the cases of myasthenia gravis, the thumbs gland is enlarged. In some cases, thymomas, a tumor of the thymus gland, is also present. The thymus gland is believed to trigger or produce the antibodies that lead to myasthenia gravis.(3)
Other Reasons– Although the presence of myasthenia gravis antibodies is the hallmark for diagnosis of the myasthenia gravis, almost 10% of patients do not have myasthenia gravis antibodies. Such type of myasthenia gravis is known as seronegative myasthenia gravis. The symptoms of both types are similar, and the seronegative myasthenia gravis is diagnosed through the physical symptoms and through the response to treatment.
Myasthenia Gravis Risk Factors
Following are the risk factors that increase the severity of the disease or transform the disease form the remission to the active stage:
Illness– During illness, the body becomes inactive which leads to an increased in the severity of myasthenia gravis. Viral infection triggers the symptoms of myasthenia gravis.
Stress– Stress, both physical and emotional, contributes to the progression of myasthenia gravis. Thus, physical stress should be avoided, and mental stress should be managed.
Fatigue– Myasthenia gravis is characterized by weakness of the muscles. Fatigue increases the severity of the condition.
Other Factors– Various other factors that increase the risk of development of myasthenia gravis are environmental factors, smoking, alteration in sex hormones and exposure to pathogens.
Myasthenia gravis is an autoimmune disease but the exact cause for abnormal behavior of the immune system is not exactly known. Other causes for myasthenia gravis include thymus abnormality and genetics. In some cases, there is an absence of antibodies. Various risk factors such as fatigue, illness, and stress also contribute to the progression of myasthenia gravis.