APP and Alzheimer disease: In this study, we used magnetic-activated cell sorting (MACS) to isolate CD11b+ cells from the cortex of APP/PS1 (APPswe and PSEN1dE9) AD model mice, and identified a novel microglia-enriched circRNA (circDlg1), which was stably expressed and specifically upregulated in the microglia of APP/PS1 mice and AD patients.