TREX1 and Aicardi-Goutieres syndrome: AGS is caused by mutations in genes involved in nucleic acid metabolism such as those encoding the Three Prime Repair Exonuclease 1 (TREX1) (Rice et al., 2007), the RNASEH2 (Crow et al., 2006) and the triphosphohydrolase SAMHD1 (Coquel et al., 2018).