Determine whether there are biomarkers associated with PD susceptibility and/or progression in exosome‐proteomes;Determine if leucine‐rich repeat kinase 2 (LRRK2) expression and/or phosphorylation are significantly lowered in the exosomes of individuals treated with the potent LRRK2 kinase inhibitor sunitinib (a multikinase inhibitor compound), to establish an assay for on‐target effects for future LRRK2 inhibitor clinical trials. Here, LRRK2 is linked to Parkinson disease.