GRN and frontotemporal dementia: GRN gene mutations have been associated to a wide spectrum of clinical phenotypes, mainly behavioral variant frontotemporal dementia (FTD), with typical TAR DNA‐binding protein 43 (TDP‐43) pathology, but also primary progressive aphasia, atypical Alzheimer's disease, and atypical parkinsonism, mainly corticobasal syndrome (CBS).1