Over a decade has passed since the discovery of MuSK antibodies in myasthenia [3] but, although in vivo transfer and active immunization studies have confirmed the pathogenicity of MuSK antibodies, whether MuSK antibodies reduce MuSK function, reduce MuSK levels, or damage the structure and function of the neuromuscular junction by other mechanisms is still unclear. Here, MUSK is linked to Fatigable weakness.