GRN and Parkinson disease: Though C9orf72, GRN and MAPT mutations most often result in bvFTD, they occasionally result in other neurodegenerative syndromes including primary progressive aphasia, amyotrophic lateral sclerosis, corticobasal syndrome, progressive supranuclear palsy, and parkinsonism (Le Ber et al., 2008; Kelley et al., 2009; Convery et al., 2019).