These include vascular disease, trauma, infection, primary or metastatic tumor, excess alcohol consumption, vitamin deficiency, Creutzfeldt-Jakob disease, and immune-mediated cerebellar ataxias such as multiple sclerosis, gluten ataxia, anti-GAD (glutamic acid decarboxylase) ataxia, and paraneoplastic cerebellar degenerations. The gene discussed is GAD1; the disease is paraneoplastic cerebellar degeneration.