SNCA and Parkinson disease: For instance, the role of α-Syn in triggering PD pathology is quite clear in specific genetic forms of PD resulting from mutations in the SNCA gene or α-Syn overexpression (misfolding proteins aggregate and propagate through a prion-like mechanism) [25,26,27,28,29,30]; this is not the same in sporadic PD, where α-Syn pathology could be considered a compensatory, or even a protective, effect [6].