CNTNAP2 and Isaacs syndrome: The main IgG4 antibody-mediated neurological disorders (IgG4-ND) include MuSK myasthenia, autoimmune nodopathies with antibodies against nodal-paranodal cell-adhesion molecules (neurofascin-155 (NF155), contactin-associated protein 1 (Caspr1), and neurofascin isoforms (NF140/186), Morvan syndrome, or neuromyotonia, anti-LGI1- and CASPR2-associated limbic encephalitis, and several cases of the anti-IgLON5 and anti-DPPX-spectrum CNS diseases.