Given the strong neuroinflammatory phenotypes in AD, it is not surprising that many AD-associated risk genes identified through genome-wide association studies, e.g. CD33, INPP5D, CLU, CR1, SPI1, ABCA7, EPHA1, the MS4A gene cluster, and TREM2 have been implicated in the adaptive and innate immune systems [220–223]. Here, CLU is linked to Alzheimer disease.