Mutations in the gene glucosidase, beta acid 1 (GBA), encoding the lysosomal ceramide metabolism enzyme glucocerebrosidase (GCase), are the strongest genetic risk factor for PD and dementia with Lewy bodies, increasing risk of developing PD by approximately 5-fold in GBA mutation carriers compared to non-carriers [9–11]. The gene discussed is GBA1; the disease is Lewy body dementia.