The Search for Premotor PD Biomarkers. 1. In order to discover premotor PD biomarkers, it is necessary to first enrich for patient population more likely to develop PD. Patients with genetic susceptibility markers, for example, parkin and LRRK2 mutations, and clinical biomarkers, hyposmia, RBD, constipation, and depression. 2. Patients with genetic markers and clinical phenotypes will undergo screening for neuroimaging changes known to correlate with PD. 3. After verification with neuroimaging, various patient tissues where the presence of biochemical markers has already been verified will be acquired (blood, CSF, saliva, and skin). 4. Premotor PD biomarker assessment and identification will use changes in the levels of known biochemical markers, i.e., α-synuclein, uric acid, DJ-1, in addition to others identified through unbiased profiling.