Editing Longevity (section)

===Genetics===
{{Further|Genetics of aging}}
[[Twin study|Twin studies]] have estimated that approximately 20-30% of the variation in human lifespan can be related to [[genetics]], with the rest due to individual behaviors and [[environmental factor]]s which can be modified.<ref>{{cite journal | vauthors = vB Hjelmborg J, Iachine I, Skytthe A, Vaupel JW, McGue M, Koskenvuo M, Kaprio J, Pedersen NL, Christensen K | display-authors = 6 | title = Genetic influence on human lifespan and longevity | journal = Human Genetics | volume = 119 | issue = 3 | pages = 312–321 | date = April 2006 | pmid = 16463022 | doi = 10.1007/s00439-006-0144-y | s2cid = 8470835 }}</ref> Although over 200 gene variants have been associated with longevity according to a US-Belgian-UK research database of human genetic variants<ref>{{Cite web|title=LongevityMap|url=http://genomics.senescence.info/longevity/|access-date=2013-09-23|work=Human Ageing Genomic Resources|publisher=senescence.info by [[João Pedro de Magalhães]]|date=n.d.|archive-date=2013-09-21|archive-url=https://web.archive.org/web/20130921223946/http://genomics.senescence.info/longevity/|url-status=live}}</ref> these explain only a small fraction of the heritability.<ref>{{cite journal | vauthors = Budovsky A, Craig T, Wang J, Tacutu R, Csordas A, Lourenço J, Fraifeld VE, de Magalhães JP | display-authors = 6 | title = LongevityMap: a database of human genetic variants associated with longevity | journal = Trends in Genetics | volume = 29 | issue = 10 | pages = 559–560 | date = October 2013 | pmid = 23998809 | doi = 10.1016/j.tig.2013.08.003 }}</ref>

[[Lymphoblast]]oid cell lines established from blood samples of [[centenarians]] have significantly higher activity of the DNA repair protein PARP ([[Poly ADP ribose polymerase]]) than cell lines from younger (20 to 70 year old) individuals.<ref name="pmid9587069">{{cite journal | vauthors = Muiras ML, Müller M, Schächter F, Bürkle A | title = Increased poly(ADP-ribose) polymerase activity in lymphoblastoid cell lines from centenarians | journal = Journal of Molecular Medicine | volume = 76 | issue = 5 | pages = 346–354 | date = April 1998 | pmid = 9587069 | doi = 10.1007/s001090050226 | s2cid = 24616650 }}</ref> The lymphocytic cells of centenarians have characteristics typical of cells from young people, both in their capability of priming the mechanism of repair after {{chem2|link=Hydrogen peroxide|H2O2}} sublethal [[DNA oxidation|oxidative DNA damage]] and in their PARP gene expression.<ref name="pmid17518695">{{cite journal | vauthors = Chevanne M, Calia C, Zampieri M, Cecchinelli B, Caldini R, Monti D, Bucci L, Franceschi C, Caiafa P | display-authors = 6 | title = Oxidative DNA damage repair and parp 1 and parp 2 expression in Epstein-Barr virus-immortalized B lymphocyte cells from young subjects, old subjects, and centenarians | journal = Rejuvenation Research | volume = 10 | issue = 2 | pages = 191–204 | date = June 2007 | pmid = 17518695 | doi = 10.1089/rej.2006.0514 }}</ref> These findings suggest that elevated PARP gene expression contributes to the longevity of centenarians, consistent with the [[DNA damage theory of aging]].<ref>{{cite book |vauthors=Bernstein H, Payne CM, Bernstein C, Garewal H, Dvorak K  |chapter=1. Cancer and aging as consequences of un-repaired DNA damage |chapter-url=https://www.novapublishers.com/catalog/product_info.php?products_id=43247  |editor-first=Honoka |editor-last=Kimura |editor2-first=Aoi |editor2-last=Suzuki |title=New Research on DNA Damages  |publisher=[[Nova Science Publishers, Inc.]] |date=2008 |isbn=978-1-60456-581-2 |pages=1–47 |oclc=213848806}}</ref>

[[File:Healthspan, parental lifespan, and longevity are highly genetically correlated.webp|thumb|upright 1.3|"Healthspan, parental lifespan, and longevity are highly genetically correlated."<ref name="Multivariate"/>]]
In July [[2020 in science|2020]], scientists used public [[List of biological databases|biological data]] on 1.75 m people with known lifespans overall and identified 10 [[Locus (genetics)|genomic loci]] which appear to intrinsically influence [[healthspan]], lifespan, and longevity – of which half have not been reported previously at [[Genome-wide association study|genome-wide significance]] and most being associated with [[cardiovascular disease]] – and identified [[Human iron metabolism|haem metabolism]] as a promising candidate for further research within the field. Their study suggests that high levels of iron in the blood likely reduce, and genes involved in metabolising iron likely increase healthy years of life in humans.<ref name="ironmeta">{{cite news |title=Blood iron levels could be key to slowing ageing, gene study shows |url=https://phys.org/news/2020-07-blood-iron-key-ageing-gene.html |access-date=18 August 2020 |work=phys.org |language=en |archive-date=16 March 2022 |archive-url=https://web.archive.org/web/20220316201154/https://phys.org/news/2020-07-blood-iron-key-ageing-gene.html |url-status=live }}</ref><ref name="Multivariate">{{cite journal |vauthors=Timmers PR, Wilson JF, Joshi PK, Deelen J |date=July 2020 |title=Multivariate genomic scan implicates novel loci and haem metabolism in human ageing |journal=Nature Communications |volume=11 |issue=1 |pages=3570 |bibcode=2020NatCo..11.3570T |doi=10.1038/s41467-020-17312-3 |pmc=7366647 |pmid=32678081 |doi-access=free}}</ref>