Next to PLCG2, GWA studies of AD identified additional immune- and microglia-related genes that associate with AD, e.g. the triggering receptor expressed on myeloid cells 2 (TREM2) gene and pathway analysis based on these same GWA studies indicate that the immune system plays a key role in the development of AD [47]. The gene discussed is TREM2; the disease is Alzheimer disease.