GAD2 and cerebellar ataxia: IgG autoantibodies (aAB) to the glutamate decarboxylase 65 (GAD65) are increasingly recognized in neurological diseases of the central nervous system, e.g., in stiff person-syndrome (SPS) (1, 2), limbic encephalitis (3), Batten’s disease (4), or cerebellar ataxia (5).