This study aims to study the natural progression of P-SYN quantification by conducting skin biopsies in patients with Parkinson's Disease (PD) and REM sleep behavior disorder (RBD). Participation will be over an 18-month period and will include skin biopsies and clinical examinations every six months. Subjects will be male or female between the ages of 50-100 and have a diagnosis of PD or RBD.

This is an observational study to further characterize and quantify disease severity
and impact (including change over time) in individuals with either segmental, multifocal, or generalized dystonia. Subjects will be aged 12-65 years old and clinically diagnosed with isolated (or primary) dystonia. Participation will include 2 visits over 120 days in which subjects will be asked to answer questions about their dystonia and related symptoms.

This is a study of oral "CVN424" at two dose levels in Parkinson's Disease (PD) patients with motor fluctuations (wearing off of PD medications). Participation will last about 14 weeks. Patients must be at least 30 and have considerable wearing off periods.

This study will test if bemdaneprocel (the "study drug") is safe and effective in improving symptoms in participants with Parkinson's Disease. The symptoms of PD are due to a loss of cells that make a specific chemical in your brain called dopamine. The study drug is a cell therapy that contains live brain cells that produce dopamine. This study will last 5 to 8 years, and depending on randomization group between 23-32 study visits.