More recently, Sayed et al. (2021) found that microglia from AD patients with R47H TREM2 were hyperactivated consistent with increased TREM2 signaling, and they generated mice expressing heterozygous R47H and found this exacerbated tauopathy, consistent with the toxic gain‐of‐function of R47H found here. Here, TREM2 is linked to Alzheimer disease.