Molecular and Functional Imaging in Monogenic PD Study This study is focused on finding a biomarker for Parkinson's Disease (PD). A biomarker is like a signal that helps doctors identify and understand a disease. PD is a condition that affects the brain, leading to symptoms like slow movement, stiffness, and shaking because of nerve cell problems. The cause of PD is unknown, and there's no existing biomarker for it. Some people get PD due to genetic mutations, and studying these cases can help find treatments. The study involves using imaging tests like PET (Positron Emission Tomography), SPECT (Single Photon Emission Computed Tomography), and MRI (Magnetic Resonance Imaging) to see changes in the brain.

• Participants will have four visits over three months, each lasting about six hours.
• Visits include scans, an optional lumbar puncture, and blood samples.
• Participants must agree to travel to the research site and follow specific health guidelines.

Note: People with certain medical conditions or using specific medications may not be eligible. Participants must be able to understand study procedures and follow contraceptive guidelines if applicable.