Given the genetic divergence between many human and mouse AD risk genes, including CD33, CR1, apolipoprotein E (APOE), HLA‐DRB1, MEF2C, and OAS1, this chimeric model further serves as an important approach to assess the uniquely human responses of microglia to AD pathologies.6, 14, 15. The gene discussed is HLA-DRB1; the disease is Alzheimer disease.