Outcomes required reporting on at least one of the following domains: motor function (e.g., Movement Disorder Society-Unified Parkinson's Disease Rating Scale {MDS-UPDRS}), non-motor symptoms (e.g., Non-Motor Symptoms Scale {NMSS}), cognitive function (e.g., Montreal Cognitive Assessment {MoCA}, Scales for Outcomes in Parkinson's disease-Cognition {SCOPA-COG}), or neurobiological markers (e.g., high-sensitivity C-reactive protein {hs-CRP}, Dopamine Transporter Scan {DaTscan}). The gene discussed is SLC6A3; the disease is Parkinson disease.