CNTNAP2 and nervous system disorder: In three different neurological disorders with IgG4 subclass antibodies, targeting leucine-rich, glioma-inactivated 1 (Lgi1), contactin-associated protein 2 (Caspr2), and Neurofascin155, respectively, a pathogenic mechanism has been suggested that is based on the block of protein–protein interaction (70, 80, 87, 93, 248).