SMPD1 and synucleinopathy: Polymorphisms in genes encoding lysosomal enzymes, acid sphingomyelinase (SMPD1 gene), and β-glucocerebrosidase (GBA, GBA1 gene), are also risk factors for synucleinopathies (Neumann et al., 2009; Dagan et al., 2015; Gan-Or et al., 2015).