For instance, recessive mutations in RNAse H1, an enzyme digesting the RNA components of DNA-RNA hybrids, present in both the nucleus, together with RNAse H2, responsible for Aicardi–Goutieres syndrome, as well as mitochondria, where only RNAse H1 is found. The gene discussed is RNASEH1; the disease is Aicardi-Goutieres syndrome.