Marker. 1  Noun. A line of credit extended by a casino or cardroom. 2  Noun. A small object placed on top of a player's hand for the purpose of preventing it from being mucked or fouled. 3  Noun. A plastic device used to denote who is in the dealer's position.
Myasthenia gravis is caused by a defect in the transmission of nerve impulses to muscles. It occurs when normal communication between the nerve and muscle is interrupted at the neuromuscular junction -- the place where nerve cells connect with the muscles they control.
Causes/Inheritance. What causes myasthenia gravis (MG)? The immune system normally defends the body against diseases, but sometimes it can turn against the body, leading to an autoimmune disease. MG is just one of many autoimmune diseases, which include arthritis and type 1 diabetes. In all of these diseases, an army of immune cells that would normally attack bacteria and disease-causing germs mistakenly attacks cells and/or proteins that have essential functions in the body.