 This is a prospective observational study. Blood samples and clinical data will be collected at the first and only study visit. The expression levels of 5 to 6 genes will be analyzed by blinding technicians concerning the diagnosis, demographic data and clinical data, which will be revealed after sending PDx gene expression values to the clinical sites. The gene expression levels will be compared between Parkinsons disease patients to the differential diagnosis cohort and healthy controls. The primary aim of the study is to design and validate a clinical classifier that will aid the physician in the diagnosis of Parkinsons disease patients. The analysis will be performed in two stages: Stage 1 Exploration analysis and Stage 2 Validation. After one year of taking a blood sample, the study physician will contacted to confirm the patients diagnosis. 