GBA1 and Gaucher disease: Glucocerebrosidase (GBA1) gene mutations, encoding gluco-cerebrosidase 1 (GCase 1) which catabolizes glycolipid glucocerebroside to ceramide and glucose in lysosome (Bae et al., 2015) and responsible for Gaucher disease, are the most common genetic risk factor for PD (Taguchi et al., 2017).