GRN and Parkinson disease: The phenotypic spectrum of variants in GRN and MAPT often includes atypical parkinsonism that might even predominate over the clinical presentation.1 Interestingly, both GRN and MAPT represent PD susceptibility/risk loci discovered through association studies, and their protein products are functionally related to PD proteins.29,30 Thus, at least GRN and MAPT should be tested routinely in PD patients.