Autoimmune epilepsy has been associated with various neuronal cell surface antigens, including LGI1, N-methyl-D-aspartate receptor (NMDA-R), α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), GABA-B, and metabotropic glutamate receptor 5 (mGluR5), as well as intracellular antigens like glutamic acid decarboxylase 65 (GAD65), antineuronal nuclear antibody type 1 (ANNA-1), and small cell lung carcinoma (Ma). Here, GRM5 is linked to small cell lung carcinoma.