This has been already noted in a nodal CIDP patient, who was switched from IgG3 against CNTN1/CASPR1 to IgG4 against CASPR1 and stopped responding to IVIg [36]; the reverse has occurred in a MuSK-MG patient where a switch from IgG4 to IgG1 anti-MuSK antibodies was associated with stable remission [37]. This evidence concerns the gene MUSK and myasthenia gravis.