ADAR and nervous system disorder: ADARs are required during embryogenesis of mammals, since knock-out models for both ADAR1 and ADAR2 are not viable and die during embryonic development or shortly after birth due to over-stimulation of the immune system; hepatic and hematopoietic disorders (ADAR1 knockout); or from neurological disorders (ADAR2 knockout) [38,39,40,41].