Glutamic acid decarboxylase (GAD) is the main target of humoral autoimmunity in patients with insulin-dependent diabetes mellitus (IDDM) and stiff-person syndrome. Wereviewed the case of a 46-year-old womanwhohad cerebellar ataxia before getting stiff-person syndromeand IDDMwith high anti-GAD autoantibody titers. This was a rare case in which there were both the clinical symptomsof stiff-person syndromeand cerebellar ataxia. In western blot analysis her serum reacted with 65-kDa proteins from

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... t cerebellum, cerebral cortex, and spinal cord. Autoantibodies to GADmay cause functional impairment of y-aminobutyric acid (GABA)neurons in the spinal cord as well as in the cerebellum. (Internal Medicine 40: 968-971, 2001)