Previous studies demonstrated that GAD65Ab present in SPS patients decrease GABA synthesis [26, 38, 41], while GAD65Ab present in CA do not affect GAD65 enzyme activity but may interfere with GABA release, either by inhibiting the packaging of GABA into vesicles and/or by impeding with the subsequent shuttling of vesicles to the synaptic cleft [7, 26] (Table 1). The gene discussed is GAD2; the disease is stiff-person syndrome.