Notably, the C9 DAM, believed to be generated from mature microglia in neurodegenerative diseases, exhibited a transcriptional profile resembling immature microglia, in accordance with their “fetal like reprogramming” observed in Alzheimer's disease.[66] Moreover, we identified a series of genes whose up‐ or down‐regulation might influence the maturation of various microglial subtypes (Figure 5G). Here, C9 is linked to early-onset autosomal dominant Alzheimer disease.