Editing Gene knockout (section)

==Types==

===Conditional knockouts===
{{Main|Conditional gene knockout}}
A conditional gene knockout allows gene deletion in a tissue in a tissue specific manner. This is required in place of a gene knockout if the null mutation would lead to [[embryonic death]],<ref>{{Cite journal|last1=Le|first1=Yunzheng|last2=Sauer|first2=Brian|date=2001-03-01|title=Conditional gene knockout using cre recombinase|journal=Molecular Biotechnology|volume=17|issue=3|pages=269–275|doi=10.1385/MB:17:3:269|pmid=11434315|s2cid=41578035|issn=1073-6085}}</ref> or a specific tissue or cell type is of specific interest. This is done by introducing short sequences called loxP sites around the gene. These sequences will be introduced into the germ-line via the same mechanism as a knockout. This germ-line can then be crossed to another germline containing [[Cre recombinase|Cre-recombinase]] which is a viral enzyme that can recognize these sequences, recombines them and deletes the gene flanked by these sites.<ref>{{Cite journal |last=Kos |first=Claudine H. |date=June 2004 |title=Methods in Nutrition Science: Cre/loxP System for Generating Tissue-specific Knockout Mouse Models |url=https://academic.oup.com/nutritionreviews/article-lookup/doi/10.1111/j.1753-4887.2004.tb00046.x |journal=Nutrition Reviews |language=en |volume=62 |issue=6 |pages=243–246 |doi=10.1111/j.1753-4887.2004.tb00046.x}}</ref> Other recombinases have since been created and employed in conditional knockout experiments.<ref>{{Cite journal |last1=Tian |first1=Xueying |last2=Zhou |first2=Bin |date=January 2021 |title=Strategies for site-specific recombination with high efficiency and precise spatiotemporal resolution |journal=Journal of Biological Chemistry |volume=296 |pages=100509 |doi=10.1016/j.jbc.2021.100509 |doi-access=free |issn=0021-9258 |pmc=8050033 |pmid=33676891}}</ref>