CNTNAP2 and Hyponatremia: LGI1 (leucine-rich, glioma-inactivated 1 protein) and CASPR2 (contactin-associated protein 2) antibody encephalitis have a broad spectrum of phenotypes; however, common symptoms include seizures (including faciobrachial dystonic seizures in LGI1-antibody encephalitis), cognitive disturbances, dysautonomia and hyponatremia [95].