RNASEH2ARibonuclease H2 subunit A, also known as RNase H2 subunit A, is an enzyme that in humans is encoded by the RNASEH2A gene.FunctionThe protein encoded by this gene is a component of the heterotrimeric type II ribonuclease H enzyme. The other two subunits are the non-catalytic RNASEH2B and RNASEH2C. RNaseH2 is the major source of ribonuclease H activity in mammalian cells and endonucleolytically cleaves ribonucleotides. It is predicted to remove Okazaki fragment RNA primers during lagging strand DNA synthesis and to excise single ribonucleotides from DNA-DNA duplexes.Clinical significanceMutations in this gene cause Aicardi–Goutières syndrome, an autosomal recessive neurological disorder characterized by progressive microcephaly and psychomotor retardation, intracranial calcifications, elevated levels of interferon-alpha and white blood cells in the cerebrospinal fluid.