Test Details: Myasthenia gravis is an antibody mediated autoimmune neuromuscular disorder that induce weakness in the skeletal muscle. Symptoms of myasthenia gravis include drooping eyelid, double vision, difficulty in chewing, weak neck muscle and difficulty in walking. Ach receptor antibody test is reliable for diagnosing autoimmune myasthenia gravis. This test is highly specific. MUSK antibody test helps to diagnose myasthenia gravis. This test is done when acetylcholine receptor antibody test is negative. anti-Musk antibodies are autoantibodies produced by the immune system that mistakenly attacks proteins called muscle specific kinase.