Autoimmune encephalitis-related autoantibodies, including N-methyl-D-aspartate-receptor (NMDAR) antibodies, contactin associated protein 2 (CASPR2) antibodies, leucine-rich glioma inactivated 1 (LGI1) antibodies, α-amino-3-hydroxy-5-methyl-isoxazolepropionic acid receptor (AMPAR) antibodies, and gamma-aminobutyric acid (GABA) receptor antibodies, were negative both in serum and CSF. This evidence concerns the gene CNTNAP2 and autoimmune encephalitis.