The laboratory hallmarks comprise hyponatremia, positive LGI1 antibodies in serum and cerebrospinal fluid (CSF) using cell-based assay (CBA), tissue-based assay (TBA) using rat hippocampus and cerebellum [2], and increased signals on fluid-attenuated inversion recovery (FLAIR) highly restricted to the medial temporal lobes [3]. The gene discussed is LGI1; the disease is Hyponatremia.