RecruitingDiagnostic testThe GBA Multimodal Study in Parkinson's DiseaseThis study plans to analyze the molecular and clinical mechanisms of the relationship between the GBA mutations and Parkinson's disease. This will be assessed through the use of advanced neuroimaging techniques called PET (positron emission tomography) to study the accumulation of the tau protein and the dysfunction of acetylcholine and dopamine in the brain of people with a mutation in the GBA gene, with and without Parkinson's disease. The ingestigators will also use a technology-based assessment to study the typing patterns as possible biomarkers of early motor dysfunctions.