To date, variants in at least 9 genes have been identified, which together underlie most cases of Aicardi–Goutières syndrome (AGS): TREX1 (MIM: 225750), RNASEH2A (MIM: 610333), RNASEH2B (MIM: 610181), RNASEH2C (MIM: 610329), SAMHD1 (MIM: 612952), ADAR1 (MIM: 615010), IFIH1 (MIM: 615846), LSM11 (MIM: 619486), and RNU7-1 (MIM: 619487) (122–127). The gene discussed is SAMHD1; the disease is Aicardi-Goutieres syndrome.