CNTNAP2 and Isaacs syndrome: Autoantibodies targeting CASPR2, a neuronal cell-adhesion protein, are linked to a spectrum of overlapping neurological disorders such as autoimmune limbic encephalitis, Isaacs syndrome (peripheral nerve hyperexcitability with cramps and fasciculations, neurogenic pain, dysautonomia) and Morvan syndrome (peripheral nerve hyperexcitability, severe insomnia, dysautonomia, dream-like enactment behavior, and visual hallucinations) [79].