High Quality Content by WIKIPEDIA articles! RNA silencing (also called as post-transcriptional gene silencing PTGS) refers to a family of gene silencing effects by which the expression of one or more genes is downregulated or entirely suppressed by the introduction of an antisense RNA molecule. The most common and well-studied example is RNA interference, in which endogenously expressed microRNA or exogenously derived small interfering RNA induces the degradation of complementary messenger RNA. It also plays an important role in defending plants against viruses. Enzymes detect double stranded RNA (that is not normally found in cells) and digest it into small pieces that are not able to cause disease.