The main objective of the study is to design and validate the blood based PDx gene expression and miRNA assay for the early diagnosis of Parkinson's disease patients. Differential diagnosis includes patients with Multiple System Atrophy, Progressive Supranuclear Palsy, Corticobasal Degeneration, Lewy Body Dementia, Essential Tremor and Normal Controls.

In this study, the PDx assay will be designed and validated in order to distinguish between Idiopathic Parkinson's disease (PD) to patients with similar symptoms and healthy controls. The differential diagnosis cohort includes patients diagnosed with Multiple System Atrophy (MSA), Progressive Supranuclear Palsy (PSP), Corticobasal Degeneration (CBD), Essential Tremor (ET) or Lewy Body Dementia (LBD) and Healthy Controls.

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 Parkinson's disease patients to the differential diagnosis cohort and healthy controls. Additional mRNA and miRNA markers will be explored. The primary aim of the study is to design and validate a clinical classifier that will aid the physician in the diagnosis of Parkinson's 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 patient's diagnosis.

Blood samples will be collected at specialized movement disorder clinics.

Medical history, clinical diagnostic features, family history in regard to Parkinson's disease, use of medication and routine imaging assessment (not mandatory) will be collected at the first and only patient visit.

Inclusion Criteria:

• Patient is able and willing to read the informed consent form
• Patient with clinical diagnosis of Idiopathic Parkinson's Disease according to Queen Square Brain Bank Criteria up to one year prior to enrollment in study
• Patient with diagnosis of MSA, PSP, CBD, Lewy Body Dementia, Essential Tremor or Healthy Control
• Men and Women aged 40-80 years
• Willing and able to comply with procurement of blood sample

Exclusion Criteria:

• Any medical, psychiatric or other conditions which, in the opinion of the investigator, would preclude participation
• Pregnancy

Movement disorder clinics