GBA1 and Lewy body dementia: The greatest risk factor, however, for both PD and the related α-synucleinopathy Dementia with Lewy Bodies (DLB), is mutations in the glucosylceramidase-beta (GBA) gene, which encodes the lysosomal enzyme glucocerebrosidase (GCase) (Clark et al., 2010; Tsuang et al., 2012), implicating aberrant sphingolipid metabolism in PD pathogenesis.