Mutations in any of the following nine genes may result in the AGS phenotype: TREX1 (AGS1, OMIM #225,750), RNASEH2B (AGS2, OMIM #610,181), RNASEH2C (AGS3, OMIM #610,329), RNASEH2A (AGS4, OMIM #606,034), SAMHD1 (AGS5, OMIM #612,952), ADAR (AGS6, OMIM #615,010), IFIH1 (AGS7, OMIM #615,846), LSM11 (AGS8, OMIM #619,486), and RNU7-1 (AGS9, OMIM #619,487). The gene discussed is SAMHD1; the disease is Aicardi-Goutieres syndrome.