How is Myasthenia Gravis best classified?

• A. Autoimmune
• B. Genetic
• C. Infectious
• D. Metabolic

Answer: (A)

Myasthenia gravis is best classified as an autoimmune disease. The body's immune system makes antibodies that target components of the neuromuscular junction, most commonly the acetylcholine receptors on the postsynaptic membrane (and in some patients, MuSK). This antibody attack reduces the number and function of receptors, diminishing the safety factor for neuromuscular transmission and producing fatigable weakness that worsens with use and improves with rest. The autoimmune mechanism is also highlighted by associations with thymic abnormalities, which often accompany MG and reflect immune system dysregulation.

This isn’t primarily a genetic disorder, an infectious disease, or a metabolic problem. It doesn’t arise from a inherited mutation in a gene in the way genetic diseases do, nor from a pathogen, nor from a metabolic derangement that disrupts energy or signaling chemistry.