TREM2 and Alzheimer disease: Some of the genes are linked to specific roles in BBB development, function, and regulation (Zhao et al., 2015) but have also been linked with AD associated changes, such as OCLN (Romanitan et al., 2007), COL4A1 (Pang et al., 2019; Xiao et al., 2021), NOTCH3 (Sassi et al., 2018), CSF1R (Sassi et al., 2018), TREM2 (Guerreiro et al., 2013), and TYROBP (Audrain et al., 2021).