SNCA and Parkinson disease: After the discovery of the key roles of alpha-synuclein in Lewy body pathology in PD and related disorders (MSA, PSP) and tau, phosphorylated-tau and amyloid-beta (1-42) in neurofibrillary tangles and plaques in Alzheimer’s disease (AD), major research efforts have been directed to the measurements of these proteins in body fluids, particularly in CSF.