Genome-wide bulk RNA sequencing of FACS-isolated microglia from 4-month-old GF 5xFAD males revealed increased expression of genes associated with AD-related activation (Axl, Cst7, Itgax, Cd9 or Clec7a), Aβ detection and clearance (Apoe and Trem2), and reduced expression of the homeostatic marker P2ry12 compared with those in SPF controls [109]. The gene discussed is TREM2; the disease is Alzheimer disease.