In frontotemporal dementia caused by progranulin gene (GRN) mutation (FTD-GRN), deficits in PGRN lead to pathological processes, including TDP-43 accumulation [54], lysosomal dysfunction, complement activation, neuroinflammation, and astrogliosis, as well as accumulation of neuronal debris [44,54,55], as illustrated in Figure 1A. The absence of PGRN drives age-related changes in microglia, shifting the neuroimmune cells from a healthy to a disease-specific state. Here, GRN is linked to frontotemporal dementia.