TREM2 and Alzheimer disease: Genome‐wide associated studies (GWASs) have identified a plethora of AD risk factors, which include triggering receptor‐expressed on myeloid cells 2 (Trem2), apolipoprotein E (APOE), ATP‐binding cassette transporter (ABCA) family, CD33, and complement pathway genes.[2] Intriguingly, more than half of the risk loci that clearly involve a specific gene are significantly enriched or uniquely expressed in immune cells, particularly microglia and macrophages.[3] This intriguing finding suggests that immune molecules play a pivotal role in the development and progression of the disease.[3]