Reportedly, the experiments by the inhibition assay in the presence of unlabelled competitive proteins (McConville et al., 2004) and the immunoprecipitation assay using MuSK Ig1 domain and CRD (Otsuka et al., 2015) suggested the co-existence of antibodies against MuSK Ig1/2 domains and MuSK CRD in MuSK antibody-positive MG. Here, MUSK is linked to myasthenia gravis.