The RNASEH2C gene encodes a non-catalytic subunit of the RNase H2 ribonuclease complex. The other members of this complex are encoded by RNASEH2A and RNASEH2B. As a ribonuclease enzyme, this complex is involved in the cleavage of RNA from RNA-DNA hybrids formed during DNA replication. For example, the enzyme is believed to mediate the removal of RNA primers from lagging-strand Okazaki fragments during DNA replication.
By carrying out its function, the enzyme plays a role in preventing inappropriate immune system activation. Dysfunction of the gene results in the build-up of unneeded DNA and RNA in the cells. The body’s immune system mistakenly identifies this DNA and RNA as foreign antigens, thus triggering an immune response with severe pathological consequences. Mutations in the RNASEH2C gene are associated with Aicardi-Goutieres Syndrome 3, a rare encephalopathy characterized by microcephaly, delayed psychomotor development, chilblains, intracranial calcification and lymphocytosis in the cerebrospinal fluid.
The RNASEH2C gene is located on the long arm of chromosome 11. It spans a length of just 6 kb of DNA and its coding sequence is contained in four exons. The protein product encoded by this gene has a molecular mass of 17 kDa and consists of 164 amino acids. An additional isoform of the RNASEH2C protein exists due to alternative splicing and contains 163 amino acids. While the gene is widely expressed, overexpression is seen in peripheral blood mononuclear cells and monocytes. Homozygous mutations in the RNASEH2C gene are associated with Aicardi-Goutieres Syndrome 3. So far, the missense mutations p.R69W and p.K143I have been linked to the disorder.