The discovery of the RNA editing process in a wide range of organisms
has challenged the classical view of a co-linear flow of genetic information
from DNA via RNA to proteins, commonly referred to as the "central dogma"
of molecular biology.
RNA editing was initially described in trypanosomes where it modifies different mRNAs by the deletion and/or insertion of uridines in specific positions. Then, it has been also discovered in various organisms and generally classified in "insertion/deletion editing" (which involves the insertion or deletion of specific nucleotides) or "substitution editing" (which involves the change of a specific nucleotide).
To date, different RNA editing types have been identified. Although evolutionary unrelated, they occur in the nucleus as well as in organelles of different organisms (few events have also been described in viruses).