[Autoantibody to glutamate decarboxylase in a patient with spinocerebellar degeneration and Sjögren syndrome].

We report a 52-year-old woman with Sjögren syndrome from the age of 46, developed cerebellar ataxia, autonomic dysfunction and dysarthria at 50. She had no family history, and all known causes of cerebellar disease were excluded. Serum of the patient contained autoantibodies directed against glutamic acid decarboxylase (GAD) which was an enzyme involved in the biosynthesis of GABA. She also had autoantibodies that were specific with Sjögren syndrome (SS-A, anti-nuclear antibody). Anti-GAD antibody changed into negative after high dose intravenous and oral corticosteroid therapy, but symptoms did not improve. Western blot method revealed abnormal bands to human neuroblastoma cell line (10, 43, 49 kDa), considered relatively specific to nervous tissue. In this case cerebellar ataxia and atrophy were caused by autoimmune pathogenesis including cerebellar GABAergic system and central nerve cells.