TREX1 is an ER‐located exonuclease that digests both dsDNA and single‐stranded DNA, thereby preventing cGAS activation by degrading cytosolic DNA.[16, 17, 18]Trex1−/− fibroblasts and macrophages express elevated interferon‐stimulated genes, whereas Trex1‐deficient or Trex1‐nuclease‐deficient mice display Aicardi‐Goutières syndrome (AGS)‐like phenotypes, which can be reversed by the deletion of cGas, Mita or Ifnb1. The gene discussed is TREX1; the disease is Aicardi-Goutieres syndrome.