SLC6A3 and Classical progressive supranuclear palsy: Among the 192 patients with Parkinsonism who visited the outpatient clinic during the study period, data were reviewed for PD patients, while excluding 21 patients with Parkinson-plus syndrome (9 with progressive supranuclear palsy, 8 with multiple system atrophy, and 4 with corticobasal degeneration) and 4 with drug-induced parkinsonism (confirmed by dopamine transporter imaging).