In the past two decades α-synuclein hasbeen the center of focus in understanding the etiology of a group of overlappingneurodegenerative disorders called α-synucleinopathies, which includesParkinson’s disease (PD), Parkinson’s disease dementia (PDD), dementia withLewy bodies (DLB), multiple system atrophy (MSA) and a number of less-well characterizedneuroaxonal dystrophies. This evidence concerns the gene SNCA and multiple system atrophy.