Stiff-person syndrome following West Nile fever

Background: Stiff-person syndrome is a rare autoimmune disorder associated with antibodies against glutamic acid decarboxylase (GAD), the key enzyme in γ-aminobutyric acid synthesis. In most cases, a trigger cannot be identified. Objective: To describe a 41-year-old man who developed stiff-person syndrome and antibodies to GAD following acute West Nile virus infection. Design: A case report and a search in GenBank for common epitopes. Result: The search revealed a stretch of 12 amino acids in the NS1 protein of West Nile virus with a high degree of homology to the GAD65 region (an isoform of GAD) containing the PEVKEK motif. Conclusion: Cross-reactivity between antibodies directed against West Nile virus and GAD may have contributed to the development of stiff-person syndrome in this patient.