GRN and Alzheimer disease: Together with the fact that CSF PGRN considerably overlaps between groups, these results show that, consistent with previous data (Nicholson et al, 2014; Körtvélyessy et al, 2015; Morenas‐Rodríguez et al, 2015; Wilke et al, 2017), CSF PGRN is not useful as a diagnostic marker in AD.