α-Synuclein consists of 140 amino acids and is a natively unfolded protein that spontaneously develops into amyloid fibrils.9 In the neuronal cells of both cellular and animal models, the α-synuclein is not only aggregated but also secreted via unconventional exocytosis under various stress conditions.10, 11, 12 In PD, Lewy body pathology spreads through a highly specific and predictable pattern in the brain; α-synuclein aggregation appears in a few discrete regions of the lower brain stem and the olfactory bulbs, whereas in the later stage it disseminates to larger brain areas.13 This evidence concerns the gene SNCA and Parkinson disease.