The development and progression of dementia have been associated with the accumulation of microglia with a distinct transcriptional phenotype defined by the expression of genes including Apoe, Spp1, Lpl, and Cst7 in mice and APOE, SPP1, CD81, and APOC1 in humans, which are called disease-associated microglia (DAMs) or Alzheimer’s disease microglia, though similar states have also been observed during normal aging (38, 50, 51). Here, CD81 is linked to early-onset autosomal dominant Alzheimer disease.