SAMHD1 and Aicardi-Goutieres syndrome: AGS is caused by loss-of-function mutations in the genes encoding the three prime repair exonuclease 1 (TREX1), the ribonuclease H2 subunit (RNASEH2)A, RNASEH2B, RNASEH2C, the phosphohydrolase SAM domain and HD domain-containing protein 1 (SAMHD1), or the dsRNA-specific adenosine deaminases acting on RNA1 (ADAR1) [158, 159].