GBA1 and Parkinson disease: Aside from familial PD-related genes, the GBA gene (which encodes glucocerebrosidase: a lysosomal enzyme involved in glucosylceramide to ceramide conversion) has raised interest.84 As noted earlier, PD patients heterozygous for GBA report an increase in SPPD.18 No preclinical investigations have yet been published looking at the specific mutations seen in PD, though our unpublished data fail to demonstrate any reductions in mechanical and heat thresholds in the GBA (D409V/WT) mouse at either six or twelve months of age.