Our analysis included 406 de novo PD participants (PD diagnosis within the last 2 years and untreated at enrollment) in the PPMI cohort, comprising 140 (34.5%) women and 266 (65.5%) men, with an average age of 59.6 ± 10.0 years at PD onset; 188 healthy control (HC) volunteers, comprising 67 (35.6%) women and 121 (64.4%) men; and 61 participants who had dopamine transporter scans without evidence of dopaminergic deficit (SWEDD), comprising 23 (37.7%) and 38 (62.3%) men (see Supplementary Table 1). Here, SLC6A3 is linked to Parkinson disease.