The identification of a correlation between AD and mutations in trigger receptor genes expressed on myeloid 2 (TREM2) and the myeloid cell surface antigen sialic acid binding Ig-like lectin 3 molecule supports for the first time the link between immune changes and AD pathogenesis (Bradshaw et al., 2013; Guerreiro et al., 2013; Jonsson et al., 2013). The gene discussed is TREM2; the disease is Alzheimer disease.