CSF immunoglobulins prepared from a patient with cerebellar ataxia associated with GAD65 antibodies suppressed GABA-mediated transmission on cerebellar Purkinje cells. The IgG acted on the presynaptic terminals of GABAergic interneurons and decreased GABA release onto Purkinje cells. These inhibitory effects were most likely elicited by the GAD65 antibodies (44) (15). This evidence concerns the gene GAD2 and aceruloplasminemia.