An Observational Study of Parkinson's Disease and Other Synucleinopathies (EASE-PD)

Inclusion Criteria: * PD subjects must meet the following criteria to be eligible: 1. Age ≥ 40 years old, regardless of gender; 2. Primary PD is diagnosed according to MDS Clinical Diagnostic Criteria for Parkinson's Disease of the International Movement Disorders Association (MDS) in 2015 and the Diagnostic Criteria of Parkinson's Disease in China in 2016; 3. Hohen \& Yahr stage 1-3; 4. Receive standard treatment for at least 4 weeks before the screening visit (standard treatment is listed in the Chinese Guidelines for the Treatment of Parkinson's Disease (Fourth Edition)); 5. The subject or his/her legal representative is able to understand the content of the informed consent and provide a signed ICF. * MSA subjects must meet the following criteria to be eligible: 1. Age ≥ 40 years old, regardless of gender; 2. Patients with probable and possible MSA are diagnosed according to the Second Consensus Statement on the Diagnosis of Multiple System Atrophy and the Chinese Expert Consensus on the Diagnostic Criteria of Multiple System Atrophy in 2018; 3. The subject or his/her legal representative is able to understand the content of the informed consent and provide a signed ICF. * Healthy subjects must meet the following criteria to be eligible: 1. Age ≥ 40 years old, regardless of gender; 2. Volunteers who are in good health for their age as determined by clinical examination at the time of screening and who are free from dyskinesia as determined by a complete neurological assessment and from serious systemic disease as determined by a complete history; 3. Be able to understand the content of informed consent and agree to sign ICF. Exclusion Criteria: * Excluded if any of the following criteria is met: 1. Secondary Parkinsonism due to infection, vascular, drugs, poisons, trauma and other causes; 2. Malignant neoplasm (except basal or squamous cell skin cancer) diagnosed within the last 5 years; 3. Those with a known mental illness or substance abuse that will cause them to be unable to cooperate; 4. Patients with severe depression or suicidal behavior (including active attempt, interrupted attempt or attempted attempt) or suicidal thoughts in the past 6 months according to the clinical judgment of the investigator; 5. Pregnant or lactating women; 6. Prior treatment with drugs targeting α-synuclein; 7. Received an investigational drug or device within the previous 4 weeks; 8. The results of laboratory examination and serological virological examination are not suitable for enrollment according to the judgment of the investigator; 9. Other conditions judged by the investigator as not suitable for inclusion.