The previous study of CHIP in AD reported the potential presence of microglia-annotated cells having the same CHIP mutations as identified in blood, suggesting bone marrow-derived monocytes with CH may infiltrate into the brain and contribute to AD development.7,14 Using matched blood WGS and brain single-nucleus RNA-seq (snRNA-seq) data, we investigated the presence of microglia-annotated cells with the same mCA as in blood for the Religious Orders Study/Memory and Aging Project (ROS/MAP),15 (Fig. 2a). The gene discussed is C4B; the disease is Alzheimer disease.