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Stiff-man syndrome is a rare disorder of the central nervous system of unknown pathogenesis.We have previously reported the presence of autoantibodies against glutamic acid decarboxylase(GAD)in a patient with stiff-man syndrome,epilepsy,and insulin-dependent diabetes mellitus.GAD is an enzyme selectively concentrated in neurons secreting the neurotransmitter gamma-aminobutyric acid(GABA)and in pancreatic beta cells.We subsequently observed autoantibodies to GABA-ergic neurons in 20 of 33 patients with stiff-man syndrome.GAD was the principal autoantigen. In the group of patients positive for autoantibodies against GABA-ergic neurons,there was a striking association with organ-specific autoimmune diseases,primarily insulin-dependent diabetes mellitus.These findings support the hypothesis that stiff-man syndrome is an autoimmune disease and suggest that GAD is the primary autoantigen involved in stiff-man syndrome and the associated insulin-dependent diabetes mellitus.Our findings also indicate that autoantibodies directed against GABA-ergic neurons are a useful marker in the diagnosis of the disease. |
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