Cerebellar Dysfunction Associated Anti-glutamic Acid Decarboxylase Antibody

Glutamic acid decarboxylase (GAD) is an enzyme that catalyzes the decarboxylation of excitatory neurotransmitter, glutamate. Past couple decades, the autoimmunity against this enzyme was found to be related to many neurological conditions; stiff-person syndrome, limbic encephalitis, cerebellar ataxia, epilepsy, and abnormal eye movements. In this report, we describe a patient with history of subacute spontaneous dizziness with downbeat nystagmus and oscillopsia, who was diagnosed anti-GAD antibody-related cerebellar dysfunction.