In the MuSK antibody-positive MG patients, the recent research reported that the monovalent MuSK antibodies abolished agrin-induced MuSK phosphorylation and AChR clustering, while the divalent monospecific MuSK antibodies had the opposing effect which leads to partially induced AChR clustering; this is independent of agrin (Huijbers et al., 2019b). This evidence concerns the gene MUSK and myasthenia gravis.