The link between neuroinflammation and neurodegenerative diseases is underlined by recent findings that genetic variants of immune receptor genes, including TREM2, a gene expressed only by microglia among CNS cells, are associated with Alzheimer’s disease, frontotemporal lobar degeneration, and possibly Parkinson’s disease [57]. The gene discussed is TREM2; the disease is early-onset autosomal dominant Alzheimer disease.