TREX1 and Aicardi-Goutieres syndrome: We also develop a 3D assembloid model to study glial interactions in a cellular model of embryonic brain development revealing that TREX1-KO microglia disrupt an intermediate step in the oligodendrocyte lineage—i.e., the pre-oligodendrocyte progenitor cell (pre-OPC) to OPC progression—indicating the possibility of microglia-driven pathologies in AGS.