Gene insertion, the incorporation of exogenous genetic material into a genome, can occur naturally or can be artificially induced.

In nature, mobile elements called insertion sequences exist. They encode only the information necessary for their insertion into DNA. Depending upon the insertion sequence, they can insert at specific regions or at random. As they do not carry other genes, they tend not to be used as tools of genetic research. However, since both their insertion and exit from DNA can be disruptive, leading to the development of mutations, knowledge of their behavior is relevant to researchers. One of the disruptions, insertional duplication, is the duplication of a short region of the insertion sequence flanking the sequence itself. If the insertion sequence subsequently exits the genome, this duplicated area may be left behind, which can be disruptive if the host region of DNA codes for a protein...