GRN and frontotemporal dementia: Interestingly, it has been recently described that CSF progranulin but not serum/plasma progranulin, is reduced also in GRN-negative FTD (Wilke et al., 2017): this reduction seems extend beyond the recognized modification of CSF progranulin levels by the SNP rs5848 (Nicholson et al., 2014) and it is not directly linked to tau alterations.