SNCA and Parkinson disease: Mutated genes contribute to the pathogenesis of PD through various mechanisms (some still unknown): some by producing misfolded proteins (α-synuclein gene duplications, triplications and point mutations), others due to dysregulated mitochondrial homeostasis (Parkin, DJ1, PINK1 and FBXO7 mutations) or to altered lysosomal degradation (ATP13A2 and GBA mutations).