SNCA and Parkinson disease: These proposals must be developed primarily as a function of the two pathological features that constitute the PD signature: (i) neuronal loss in the substantia nigra pars compacta (SNpc) with dopaminergic denervation of the striatum, and (ii) intracellular protein misfolding and aggregation into pathological inclusions called Lewy bodies (LBs), the main component of which is alpha-synuclein (α-syn) [7].