High levels of antibodies against glutamic acid decarboxylase (GAD-ab) have been reported in serum of patients with several neurological syndromes, including stiff person syndrome (SPS), cerebellar ataxia, epilepsy, and limbic encephalitis (LE), all of them characterized by neurological dysfunction of the GABAergic system [1–3]. This evidence concerns the gene GAD1 and cerebellar ataxia.