GRN and Parkinson disease: In most cases, PD and MSA are pathologically linked to α-synucleinopathy, with the exceptions of parkin RBR E3 ubiquitin protein ligase (PRKN) and LRRK2 [13]; PSP, CBD and FTDP-17 associated with MAPT gene mutations (FTDP-17 (MAPT)) are linked to tauopathy; Perry syndrome and FTDP-17 associated with progranulin (GRN) gene mutations (FTDP-17 (GRN)) are linked to TAR DNA-binding protein of 43 kDa (TDP-43) proteinopathy.