GRN and frontotemporal dementia: We immunostained for progranulin, CatD, and GCase with markers of neurons (NeuN), microglia (Iba1), and astrocytes (GFAP) in frontal cortex of controls and patients with FTD-GRN or sporadic FTLD-TDP type A. Consistent with a prior report [25], we observed strong progranulin immunoreactivity in microglia (Additional file 1: Fig. S3a), suggesting that high progranulin expression by reactive microglia may mask the progranulin haploinsufficiency of patients with GRN mutations.