RCVRN and Parkinson disease: Infectious and autoimmune conditions sit between these poles: in the limited samples with imaging, Japanese encephalitis and post-COVID parkinsonism generally showed reduced uptake in the patients who were actually scanned (96, 97, 113, 116, 117); and autoimmune encephalitis (e.g., IgLON5, anti-NAE, anti-GlyR, anti-recoverin) shows reduced presynaptic signal in almost all reported cases (172, 175–178, 180, 181).