Sjögren症候群を合併し，血清抗GAD抗体陽性であった脊髄小脳変性症の1例

Autoantinbody to Glutamate Decarboxylase in a Patient with Spinocerebellar Degeneration and Sjögren Syndrome

　症例は52歳女性。Sjögren症候群で経過観察中，脊髄小脳変性症を併発し，症状は亜急性に進行した。血液中の自己抗体は，Sjögren症候群に特徴的な抗SS-A抗体や抗核抗体，抗セントロメア抗体の他に抗GAD抗体が陽性であり，これはステロイド大量療法，内服治療により陰性化した。Western blot法による抗神経細胞抗体検索では，49kDa，43kDa，約10kDaにヒト神経芽細胞腫に対する異常バンドが認められ，神経組織に比較的特異性のある抗体である可能性が示唆された。本症例の小脳失調，小脳萎縮の原因に，抗GAD抗体や抗神経細胞抗体を含む自己免疫異常が考えられた。

We report a 52-year-old woman with Sjogren 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 Sjogren syndrome (SS-A, anti-nuclear antibody). Anti-GAD antibody changed into negative after high dose intravenous and oral corticosteroid ther-apy, but symptoms did not improve.