SNCA and Parkinson disease: For example, α-synuclein is at least partly degraded in lysosomes through the activity of the lysosomal enzymes including cathepsins (McGlinchey and Lee, 2015; Prieto Huarcaya et al., 2022), and decreased activities of glucocerebrosidase (GCase) (Balducci et al., 2007; Alcalay et al., 2015), cathepsin D (Parnetti et al., 2014; Kang et al., 2021), β-glucocerebrosidase (Parnetti et al., 2017), and α-gal (Alcalay et al., 2018; Wu et al., 2008) have been reported in cerebrospinal fluid (CSF), plasma or blood of sporadic PD patients.