SLC6A3 and Parkinson disease: The pathophysiology of Parkinson`s disease (PD) is characterized by the loss of dopaminergic cell bodies in the substantia nigra1,2 and the degeneration of nigrostriatal projections.3 The impairment of dopamine-related neurotransmission in the striatum is linked to most of the classical motor features (i.e. tremor, rigidity, and bradykinesia) of early PD.4 A key molecule for dopaminergic function is the dopamine transporter (DAT), which is localized on the plasma membrane of presynaptic cell bodies, axons and nerve terminals and removes free dopamine from the synaptic cleft.5