GAD1 and autoimmune encephalitis: The target antigens in autoimmune encephalitis are either neuronal cell surface proteins and synaptic receptors such as NMDA and γ-aminobutyric acid (GABA) receptors or intracellular epitopes such as onconeural antigens (e.g., Hu and Ma2) and glutamic acid decarboxylase (GAD) [8].