Editing Human genome (section)

== Mitochondrial DNA ==

The human [[mitochondrial DNA]] is of tremendous interest to geneticists, since it undoubtedly plays a role in [[mitochondrial disease]]. It also sheds light on human evolution; for example, analysis of variation in the human mitochondrial genome has led to the postulation of a recent common ancestor for all humans on the maternal line of descent (see [[Mitochondrial Eve]]).

Due to the damage induced by the exposure to Reactive Oxygen Species mitochondrial DNA (mtDNA) has a more rapid rate of variation than nuclear DNA. This 20-fold higher mutation rate allows mtDNA to be used for more accurate tracing of maternal ancestry.{{Citation needed|date=January 2020}} Studies of mtDNA in populations have allowed ancient migration paths to be traced, such as the migration of [[Indigenous peoples of the Americas|Native Americans]] from [[Siberia]]<ref>{{cite journal | vauthors = Nielsen R, Akey JM, Jakobsson M, Pritchard JK, Tishkoff S, Willerslev E | title = Tracing the peopling of the world through genomics | journal = Nature | volume = 541 | issue = 7637 | pages = 302–310 | date = January 2017 | pmid = 28102248 | pmc = 5772775 | doi = 10.1038/nature21347 | bibcode = 2017Natur.541..302N }}</ref> or [[Polynesia]]ns from southeastern [[Asia]].{{Citation needed|date=January 2020}} It has also been used to show that there is no trace of [[Neanderthal]] DNA in the European gene mixture inherited through purely maternal lineage.<ref>{{Cite web | vauthors = Sykes B | date = 9 October 2003 | url = http://genome.wellcome.ac.uk/doc_WTD020876.html | title = Mitochondrial DNA and human history | publisher = The Human Genome | access-date = 19 September 2006 | url-status = dead | archive-url = https://web.archive.org/web/20150907140051/http://genome.wellcome.ac.uk/doc_WTD020876.html | archive-date = 7 September 2015 | df = dmy-all }}</ref> Due to the restrictive all or none manner of mtDNA inheritance, this result (no trace of Neanderthal mtDNA) would be likely unless there were a large percentage of Neanderthal ancestry, or there was strong positive selection for that mtDNA. For example, going back 5 generations, only 1 of a person's 32 ancestors contributed to that person's mtDNA, so if one of these 32 was pure Neanderthal an expected ~3% of that person's autosomal DNA would be of Neanderthal origin, yet they would have a ~97% chance of having no trace of Neanderthal mtDNA.{{Citation needed|date=January 2020}}