MUSK and myasthenia gravis: Myasthenia gravis (MG) is a B-cell-driven, T-cell-dependent autoimmune disease (AID), which results from the transmission disorder in the post-synaptic neuromuscular junction caused by the production of antibodies for acetylcholine receptors (AChRs) (1, 2) or other proteins, such as muscle-specific kinase (MuSK) (3).