SLC6A3 and Parkinson disease: 123I-FP-CIT dopamine transporter (DAT) single-photon emission computed tomography (SPECT) accurately detects presynaptic dopaminergic deficits and is highly sensitive for the diagnosis of Parkinson’s disease (PD) and parkinsonian syndromes, including dementia with Lewy bodies (DLB), progressive supranuclear palsy (PSP), corticobasal degeneration syndrome (CBS), and parkinsonism-predominant multiple system atrophy (MSA-P) [1].