IFIH1 and Aicardi-Goutieres syndrome: Interestingly, the Italian AGS population presented different mutation percentages compared to the frequency in a previously reported larger, international cohort [1]: The most frequent mutations found in our cohort are in RNASEH2B and IFIH1 genes (59% versus 36% globally, and 12% versus 3%, respectively), whereas the frequency of TREX1 mutations was lower (8% versus 22%).