However, in a multisite cross-sectional study by the Parkinson’s Progression Markers Initiative (PPMI) study group consisting of N = 158 LRRK2-PD (89% G2019S), N = 80 GBA1-PD (89% N370S), and N = 361 sPD early-stage patients (mean disease duration of 2.9 ± 1.9 years; 3.1 ± 2 years; and 2.6 ± 0.6 years, respectively), more (better) SBR DAT binding was observed in both genetic PD groups compared to sPD, restricted contra-laterally to the more affected side of the body [27], despite similar motor and cognitive symptoms between the groups. This evidence concerns the gene SLC6A3 and Parkinson disease.