Recent GWASs have revealed that triggering receptor expressed on myeloid cells 2 (TREM2), located on chromosome 6 can be involved in AD, especially in LOAD. TREM2 is a member of immunoglobulin family, and it contains a single variable domain. TREM2 is located on the membrane of several immune cells, such as macrophages and dendritic cells. Its main ligand is DNA clamp loader is Replication Factor C-activating protein of 12 kilodaltons (DAP12), which can be involved in downstream signaling. Functions of TREM2 protein can include the clearance of apoptotic cells and immunosupression.174 In an Icelandic population, a rare variant (Arg47His) has been suggested to increase the risk of impairment in inflammation, leading to LOAD.175 Other variants located in exon 2 have been shown higher percentage in AD patients, such as Glu33X or Asp87 Asn. AD, associated with TREM2 can be associated with chronic brain inflammation with aberrations in microglial phagocytosis or inflammatory pathways.176
