The investigators have recently discovered a metabolic biomarker which predicts Parkinson's disease (PD) at the early stages in patients and in animal models. The aim of BIOPARK is to investigate how the biomarker evolves in advanced PD stage, when diagnosis confirmation is higher, an in de novo PD patients who come from a different geographical area than those of the publication (since it is known that the metabolome is largely influenced by lifestyle). They will also evaluate if the biomarker is able to distinguish patients with a parkinsonian syndrome often confused with parkinson's disease, i.e. Multiple System Atrophy (MSA).