What're the risk factors for myasthenia gravis?
Myasthenia gravis occurs in all ethnic groups and both genders. It most commonly affects young adult women (under 40) and older men (over 60), but it can occur at any age.
In neonatal myasthenia, the fetus may acquire immune proteins (antibodies) from a mother affected with myasthenia gravis. Generally, cases of neonatal myasthenia gravis are transient (temporary) and the child's symptoms usually disappear within few weeks after birth. Other children develop myasthenia gravis indistinguishable from adults. Myasthenia gravis in juveniles is common.
Myasthenia gravis is not directly inherited nor is it contagious. Sometimes the disease may occur in more than one member of the same family. If a woman with myasthenia gravis becomes pregnant, sometimes the baby acquires antibodies from the mother and has myasthenia gravis symptoms for a few weeks or months after birth. This is called neonatal myasthenia, and the symptoms can be treated.
Myasthenia gravis may be associated with other autoimmune diseases. Patients with family members who suffer from disorders such as rheumatoid arthritis, scleroderma, and lupus may have an increased risk for myasthenia gravis.
Rarely, children may show signs of congenital myasthenia or congenital myasthenic syndrome. These are not autoimmune disorders, but are caused by defective genes that control proteins in the acetylcholine receptor or in acetylcholinesterase.
In rare cases, myasthenia is caused by a defective gene and appears in infants born to non-myasthenic mothers. This type is called congenital myasthenia.