SNCA and Parkinson disease: Parkinson’s disease (PD) is a movement disorder characterized pathologically by the loss of dopaminergic cells in the midbrain, and by the appearance of Lewy bodies (Braak et al., 1999; Braak et al., 2003), which are intracellular protein aggregates composed primarily of ubiquitin and α-synuclein (aSyn) (Spillantini et al., 1997; Spillantini et al., 1998).