SNCA and Parkinson disease: Recent data have shown that α-synuclein pathology spreads throughout the brain and affects several brain regions in PD patients (Braak et al., 2004), including the SN, OB, brainstem, limbic system and neocortex, in a disease-stage dependent manner (Braak and Braak, 2000; Amino et al., 2005; Orimo et al., 2007; Dickson et al., 2009; Jellinger, 2011).