Objective of the trial. To define a sub-population which is at increased risk of developing Parkinson, beyond the fact of carrying Gaucher; in this sub-population the investigators shall conduct a comprehensive evaluation that includes a variety of non-invasive tests, whose purpose is to evaluate the state of the pre- Parkinson's disease signs, signs which can appear, even twenty years before the appearance of the disease, and also to compare them to a group of diagnosed Gaucher patients and a group of healthy people who are not carriers of Gaucher disease. A group of those carriers will be available for trial or for treatment, if there will be a medicine for the prevention of the development of Parkinson, obtainable.