TREM2 and Alzheimer disease: Wang S. Y. et al. (2020), Wang Y. et al. (2020) found that knockout of Trem2 in a 5xFAD mouse model led to exacerbation of AD, with an increased burden of Aβ plaques in the hippocampus due to a dysfunctional response of microglia, in which they fail to accumulate around Aβ plaques.