SAMHD1 and Aicardi-Goutieres syndrome: Overall, mutations in one of the AGS-related genes were found in forty-eight out of fifty-one AGS patient (94%) as follows—59% of Italian AGS patients had mutations in RNASEH2B, 11% in IFIH1, 8% in TREX1, 8% in SAMHD1, 4% in RNASEH2A, 2% in RNASEH2C and 2% in ADAR1 (Figure 1 and Table 2).