Striatal DAT deficiency is commonly assessed by DAT PET ligands like 11C-CFT, 18F-CFT, 11C-PE2I, and 11Caltropane, as well as SPECT ligands like 123I-Iodoflupan and 123I-β– CIT, 123I-FP-CIT, with 99–100% sensitivity and specificity in identifying dopamine deficits in the early stages of PD (Palermo and Ceravolo, 2019). Here, SLC6A3 is linked to Parkinson disease.