Editing Expression vector (section)

===Gene therapy===
{{main|Vectors in gene therapy}}
[[Gene therapy]] is a promising treatment for a number of diseases where a "normal" gene carried by the vector is inserted into the genome, to replace an "abnormal" gene or supplement the expression of particular gene. Viral vectors are generally used but other nonviral methods of delivery are being developed. The treatment is still a risky option due to the viral vector used which can cause ill-effects, for example giving rise to [[insertional mutation]] that can result in cancer.<ref>{{cite web |url=http://www.ornl.gov/sci/techresources/Human_Genome/medicine/genetherapy.shtml |title=Gene therapy |work=Human Genome Project }}</ref><ref>{{cite news |url=https://www.theguardian.com/society/2003/oct/17/research.sciencenews |title=Doctors discover why gene therapy gave boys cancer |author=Ian Sample |work=Guardian |date=17 October 2003 }}</ref> However, there have been promising results.<ref>{{cite news |url=https://www.theguardian.com/science/2013/apr/30/gene-therapy-trials-heart-patients|title= Pioneering gene therapy trials offer hope for heart patients|author=Sarah Boseley |work=Guardian |date=30 April 2013 }}</ref><ref>{{Cite journal | last1 = Fischer | first1 = A. | last2 = Hacein-Bey-Abina | first2 = S. | last3 = Cavazzana-Calvo | first3 = M. | doi = 10.1038/ni0610-457 | title = 20 years of gene therapy for SCID | journal = Nature Immunology | volume = 11 | issue = 6 | pages = 457–460 | year = 2010 | pmid = 20485269| s2cid = 11300348 }}</ref>