SNCA and Parkinson disease: Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized both by the loss of dopaminergic neurons in the substantia nigra pars compacta and the accumulation of intracellular protein inclusions primarily made up of alpha-synuclein (aSyn), known as Lewy bodies (Spillantini et al., 1997; Baba et al., 1998; Dauer and Przedborski, 2003; Goedert et al., 2012).