Insertions and Deletions
Insertions and Deletions are grouped together as a single class of events known as "Indels." They are combined because, when comparing different genomes, it is not possible to determine whether one genome had an insertion or the other had a deletion. In these events, at least one nucleotide is inserted into or deleted from the genome. For example, assume the sequence "GAT" is inserted into the middle of a section of the genome that normally reads "ACAATA", resulting in the sequence "ACAGATATA".
As in the case with SNVs, many insertions and deletions may exist within a given genome and discerning the significance of a given Indel will depend on its location. Indels within coding regions of a gene may result in a frameshift such that the entire protein is altered. Indels in non-coding regions range from having no observable effect to influencing whether nearby genes are transcribed at all.