GBA1 and Parkinson disease: A reduction in GBA expression and activity is observed in the substantia nigra and cerebellum of patients with sporadic PD (Gegg et al., 2012), and the inhibition of GBA or its transporter Limp2 is sufficient to stimulate α-syn aggregation through autophagic inhibition (Rothaug et al., 2014; Du et al., 2015).