There are seven AGS genetic subgroups (AGS1-7), based on the mutations found in the following genes: 3′-5′ DNA exonuclease-TREX1, RNASEH2B, RNASEH2C, and RNASEH2A, SAM and HD domain-containing deoxynucleoside triphosphate triphosphohydrolase 1-SAMHD1, and adenosine deaminase acting on RNA 1-ADAR1, as well as on the RNA sensor IFN-induced helicase C domain-containing protein 1-IFIH1 (101, 110). Here, SAMHD1 is linked to Aicardi-Goutieres syndrome.