Over the years, it became also apparent by many investigators in the field, as discussed later, that since GAD is widely expressed within the central nervous system catalyzing the conversion of the excitatory neurotransmitter l-glutamate to the inhibitory gamma-aminobutyric acid (GABA), anti-GAD antibodies are also associated with other autoimmune neurological diseases manifested by neuronal excitability. Here, GAD1 is linked to autoimmune disorder of the nervous system.