SNCA and Parkinson disease: The pathological hallmarks of PD are intracellular proteinaceous inclusions called Lewy bodies (LB) and Lewy neurites (LN) that are predominantly formed of misfolded and aggregated forms of the presynaptic protein α-Synuclein (α-Syn), and the loss of dopaminergic (DA) neurons in the substantia nigra (SN) (Spillantini et al., 1997; Lang and Lozano, 1998a,b).