In line with the pronounced IFN-I signature in SAMHD1, RNASEH2B, and TREX1 patients, increased protein concentrations of IFN-a2 could be readily identified in the serum of these patients, but not in our RNU7-1-mutated AGS patients (Fig. 3c). This evidence concerns the gene RNU7-1 and Aicardi-Goutieres syndrome.