GAD1 and vitamin B12 deficiency: The differential diagnoses for this subacute progressive cerebellar syndrome included metabolic disorders (e.g., vitamin B12 deficiency, hypothyroidism), immune-mediated cerebellar ataxias (e.g., celiac disease, paraneoplastic syndromes, anti-GAD-associated ataxia), and chronic infections (e.g., fungal infections, central nervous system tuberculosis).