SAMHD1 and Aicardi-Goutieres syndrome: AGS is an inherited encephalopathy characterized by the dysregulation of type 1 interferon (IFN) responses and upregulation of interferon-stimulated genes (ISGs) caused by irregularities in the intracellular nucleic acid sensing machinery TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, ADAR1, or IFIH1 [194].