Since there is no specific tracer that depicts the GABAergic system, we chose to perform positron emission tomography (PET) with [11C]flumazenil(FMZ) that binds to the benzodiazepine binding site on the GABA-A receptor and [11C]CFT that binds to dopamine transporter, respectively, in early-stage PD patients. This evidence concerns the gene SLC6A3 and Parkinson disease.