SLC6A3 and Parkinson disease: DAT imaging in the nigrostriatal system is a well-established tool for the evaluation of dopaminergic function in neurodegenerative disorders, e.g., Parkinson's disease (PD) and Parkinson ́s plus-syndromes or the atypical parkinsonians (APS) (Palermo and Ceravolo 2019; Varrone and Halldin 2010).