SLC6A3 and Parkinson disease: DAT reduction correlates with dopamine neurons loss in the substantia nigra and striatum.26,114,115 This is why the striatal concentration of DAT, preferentially putamen DAT, is a highly sensitive parameter for detecting early phases of PD.39 DAT ligands are well-established markers that are useful in evaluating changes in presynaptic DAT sites in vivo and in vitro.