Genes encoding regulators of immunity, including TREM2, CR1, and many others, have been strongly implicated in AD susceptibility by human genetics (Bellenguez et al., 2022), and abundant evidence now supports a key role for many such genes among glial cells (Wang et al., 2015; Zhou et al., 2020; Keren-Shaul et al., 2017). This evidence concerns the gene CR1 and Alzheimer disease.