TREM2 and Alzheimer disease: As described by He et al., among the 50 AD-related risk loci identified through genome-wide association analysis (GWAS), more than half were significantly enriched or specifically expressed in immune cells, particularly microglia and macrophages, such as Age and apolipoprotein E (APOE), triggering receptors expressed on myeloid cells 2 (TREM2), and ATP-binding cassette subfamily A (ABCA) [117].