SPECT shows normal density of presynaptic DAT in healthy controls, patients with essential tremor and in drug-induced or psychogenic parkinsonism [104–106], whereas reduced DAT uptake is indicative of nigrostriatal degeneration and is detected in PD, PDD, MSA and PSP patients versus controls [105, 107, 108]. Here, SLC6A3 is linked to Parkinson disease.