Genetic studies further emphasize the role of glial cells in neurodegenerative diseases, with many AD risk genes expressed in microglia and astrocytes.14,15TREM2 and APOE, two strong genetic risk factors for late-onset AD (LOAD), have multifaceted roles in AD pathogenesis, including the modulation of inflammatory processes (reviewed in Martens et al.16 and Ulland and Colonna17). The gene discussed is APOE; the disease is Alzheimer disease.