CGAS and Aicardi-Goutieres syndrome: Analysis of mice with partial-loss-of-function AGS disease mutations in Rnaseh2a and Rnaseh2b, as well as experiments using Rnaseh2b knockout cells established that RNase H2 function is necessary to prevent activation of the IFN response and ISG expression in a cGAS/STING-dependent manner (Mackenzie et al. 2016; Pokatayev et al. 2016).