Editing Telomere (section)

== Measurement ==

Several techniques are currently employed to assess average telomere length in eukaryotic cells. One method is the Terminal Restriction Fragment (TRF) southern blot.<ref>{{cite journal | vauthors = Allshire RC, Dempster M, Hastie ND | title = Human telomeres contain at least three types of G-rich repeat distributed non-randomly | journal = Nucleic Acids Research | volume = 17 | issue = 12 | pages = 4611–27 | date = June 1989 | pmid = 2664709 | pmc = 318019 | doi = 10.1093/nar/17.12.4611 | display-authors = 1 }}</ref><ref>{{cite journal | vauthors = Rufer N, Dragowska W, Thornbury G, Roosnek E, Lansdorp PM | s2cid = 23833545 | title = Telomere length dynamics in human lymphocyte subpopulations measured by flow cytometry | journal = Nature Biotechnology | volume = 16 | issue = 8 | pages = 743–7 | date = August 1998 | pmid = 9702772 | doi = 10.1038/nbt0898-743 | display-authors = 1 }}</ref> There is a Web-based Analyser of the Length of Telomeres ([https://www.ceitec.eu/chromatin-molecular-complexes/rg51/tab?tabId=125 WALTER]), software processing the TRF pictures.<ref>{{Cite journal |last1=Lyčka |first1=Martin |last2=Peska |first2=Vratislav |last3=Demko |first3=Martin |last4=Spyroglou |first4=Ioannis |last5=Kilar |first5=Agata |last6=Fajkus |first6=Jiří |last7=Fojtová |first7=Miloslava |date=December 2021 |title=WALTER: an easy way to online evaluate telomere lengths from terminal restriction fragment analysis |journal=BMC Bioinformatics |language=en |volume=22 |issue=1 |page=145 |doi=10.1186/s12859-021-04064-0 |doi-access=free |issn=1471-2105 |pmc=7986547 |pmid=33752601}}</ref> A Real-Time [[Polymerase chain reaction|PCR]] assay for telomere length involves determining the Telomere-to-Single Copy Gene (T/S) ratio, which is demonstrated to be proportional to the average telomere length in a cell.<ref>{{cite journal | vauthors = Cawthon RM | title = Telomere measurement by quantitative PCR | journal = Nucleic Acids Research | volume = 30 | issue = 10 | pages = 47e–47 | date = May 2002 | pmid = 12000852 | pmc = 115301 | doi = 10.1093/nar/30.10.e47 }}</ref>

Tools have also been developed to estimate the length of telomere from [[whole genome sequencing]] (WGS) experiments. Amongst these are TelSeq,<ref>{{cite journal |doi= 10.1093/nar/gku181 |title=Estimating telomere length from whole genome sequence data |journal=Nucleic Acids Research |year=2014 | vauthors = Ding Z |volume=42 |issue=9 |pages=e75 |pmid=24609383 |pmc=4027178 }}</ref> Telomerecat<ref>{{cite journal |doi= 10.1038/s41598-017-14403-y |title=Telomerecat: A ploidy-agnostic method for estimating telomere length from whole genome sequencing data. |journal=Scientific Reports |year=2018 | vauthors = Farmery J |volume=8 |issue=1 |pages=1300 |pmid=29358629 |pmc=5778012 |bibcode=2018NatSR...8.1300F }}</ref> and telomereHunter.<ref>{{cite journal |doi= 10.1186/s12859-019-2851-0 |title=TelomereHunter–in silico estimation of telomere content and composition from cancer genomes. |journal=BMC Bioinformatics |year=2019 | vauthors = Feuerbach L |volume=20 |issue=1 |pages=272 |pmid=31138115 |pmc=6540518 |doi-access=free }}</ref> Length estimation from WGS typically works by differentiating telomere sequencing reads and then inferring the length of telomere that produced that number of reads. These methods have been shown to correlate with preexisting methods of estimation such as PCR and TRF. [[Flow-FISH]] is used to quantify the length of telomeres in human white blood cells. A semi-automated method for measuring the average length of telomeres with Flow FISH was published in Nature Protocols in 2006.<ref>{{cite journal | vauthors = Baerlocher GM, Vulto I, de Jong G, Lansdorp PM | title = Flow cytometry and FISH to measure the average length of telomeres (flow FISH) | journal = Nature Protocols | volume = 1 | issue = 5 | pages = 2365–76 | date = December 2006 | pmid = 17406480 | doi = 10.1038/nprot.2006.263 | s2cid = 20463557 }}</ref>

While multiple companies offer telomere length measurement services, the utility of these measurements for widespread clinical or personal use has been questioned.<ref>{{Cite news|url=https://www.nytimes.com/2011/05/19/business/19life.html|title=A Blood Test Offers Clues to Longevity|first=Andrew|last=Pollack|newspaper=The New York Times|date=May 18, 2011}}</ref><ref>{{cite journal | vauthors = von Zglinicki T | title = Will your telomeres tell your future? | journal = BMJ | volume = 344 | pages = e1727 | date = March 2012 | pmid = 22415954 | doi = 10.1136/bmj.e1727 | s2cid = 44594597 }}</ref> Nobel Prize winner [[Elizabeth Blackburn]], who was co-founder of one company, promoted the clinical utility of telomere length measures.<ref>{{cite journal |doi=10.1038/news.2011.330 |title=Spit test offers guide to health |journal=Nature |year=2011 | vauthors = Marchant J |doi-access=free }}</ref>