MYH14 and myasthenia gravis: The term anti-striated muscle refers to a class of antibodies against components of skeletal muscle including titin, the ryanodine receptor, myosin, and alpha-actin.They are highly associated with thymoma, being positive in 75% to 80% of MG patients with thymoma, but they are also positive in MG without thymoma, particularly in elderly patients.