Among the studies discussed in this review, a limited number have utilized human microglial cell cultures (e.g., references [36, 59, 90]), humanized knock-in mice (for molecules such as TREM2 [18, 20, 22] or LILRB4 [38]), or xenotransplantation of human microglia into AD mouse models (e.g., reference [77]), but such human-focused research remains relatively rare. This evidence concerns the gene LILRB4 and Alzheimer disease.