Gluten Ataxia Associated with Dietary Protein Cross-Reactivity with GAD-65

Abstract

Cross-reactivity occurs when antibodies formed against an antigen have amino acid sequence homology with another target protein. This allows antibodies formed against the antigen to also bind to similar proteins that share structural similarity. Autoimmune reactions to gluten can lead to sporadic ataxia in susceptible genotypes due to cross-reactivity. With gluten ataxia, dietary consumption of gluten proteins induce immunological cross-reactivity with glutamic-acid decarboxylase-65 (GAD-65) target proteins found in the cerebellum. Implementation of a strict gluten-free diet has been shown to improve the expression of this form of ataxia with most patients in this subgroup. However, there are some subjects that have limited clinical responses to only a strict gluten-free diet. Dietary protein cross-reactivity to other food proteins, besides gluten, that also share structural similarity to GAD-65 may also play a role in this reaction. In this case report, we report of a patient suffering from gluten-ataxia in which a gluten-free diet alone did not generate significant clinical outcomes until other foods that cross-react with GAD-65 were also removed from their diet.

Keywords

• idiopathic sporadic ataxia
• GAD-65
• cross-reactivity