A Case of Anti-MuSK Antibody-positive Myasthenia Gravis Presenting as Limb-Girdle Muscle Atrophy.

To diagnose a case anti-MuSK myasthenia gravis (anti-MuSK MG) is always a challenge in view of a distinct clinical phenotype that differs from typical MG (anti-acetylcholine receptors (antibody positive). We herein report a case of anti-MuSK MG, whose history and clinical phenotype differ from typical MG and are more suggestive of myopathy or anterior horn cell disease. Therefore, testing anti-MuSK antibody is very important if there is suspicion of anti-MuSK MG.