Editing DNA sequencing (section)

===Early DNA sequencing methods===
The first method for determining [[DNA sequences]] involved a location-specific primer extension strategy established by [[Ray Wu]], a geneticist, at [[Cornell University]] in 1970.<ref>{{cite web|url=http://www.mbg.cornell.edu/faculty-staff/faculty/wu.cfm|title=Ray Wu Faculty Profile|archive-url=https://web.archive.org/web/20090304121126/http://www.mbg.cornell.edu/faculty-staff/faculty/wu.cfm|archive-date=2009-03-04|publisher=Cornell University}}</ref> DNA polymerase catalysis and specific nucleotide labeling, both of which figure prominently in current sequencing schemes, were used to sequence the cohesive ends of lambda phage DNA.<ref>{{cite journal | vauthors = Padmanabhan R, Jay E, Wu R | title = Chemical synthesis of a primer and its use in the sequence analysis of the lysozyme gene of bacteriophage T4 | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 71 | issue = 6 | pages = 2510–4 | date = June 1974 | pmid = 4526223 | pmc = 388489 | doi = 10.1073/pnas.71.6.2510 | bibcode = 1974PNAS...71.2510P | doi-access = free }}</ref><ref>{{cite journal | vauthors = Onaga LA | title = Ray Wu as Fifth Business: Demonstrating Collective Memory in the History of DNA Sequencing | journal = Studies in the History and Philosophy of Science | volume = 46 | pages = 1–14 | date = June 2014 | pmid = 24565976 | doi = 10.1016/j.shpsc.2013.12.006 | series = Part C }}</ref><ref name="pmid4553110">{{cite journal | vauthors = Wu R | title = Nucleotide sequence analysis of DNA | journal = Nature New Biology | volume = 236 | issue = 68 | pages = 198–200 | year = 1972 | pmid = 4553110 | doi = 10.1038/newbio236198a0 }}</ref> Between 1970 and 1973, Wu, scientist Radha Padmanabhan and colleagues demonstrated that this method can be employed to determine any DNA sequence using synthetic location-specific primers.<ref name="pmid4560009">{{cite journal | vauthors = Padmanabhan R, Wu R | title = Nucleotide sequence analysis of DNA. IX. Use of oligonucleotides of defined sequence as primers in DNA sequence analysis | journal = Biochem. Biophys. Res. Commun. | volume = 48 | issue = 5 | pages = 1295–302 | year = 1972 | pmid = 4560009 | doi = 10.1016/0006-291X(72)90852-2}}</ref><ref name="pmid4358929">{{cite journal | vauthors = Wu R, Tu CD, Padmanabhan R | title = Nucleotide sequence analysis of DNA. XII. The chemical synthesis and sequence analysis of a dodecadeoxynucleotide which binds to the endolysin gene of bacteriophage lambda | journal = Biochem. Biophys. Res. Commun. | volume = 55 | issue = 4 | pages = 1092–99 | year = 1973 | pmid = 4358929 | doi = 10.1016/S0006-291X(73)80007-5}}</ref><ref name="Bambara Padmanabhan Wu 1974">{{cite journal | vauthors = Jay E, Bambara R, Padmanabhan R, Wu R | title = DNA sequence analysis: a general, simple and rapid method for sequencing large oligodeoxyribonucleotide fragments by mapping | journal = Nucleic Acids Research | volume = 1 | issue = 3 | pages = 331–53 | date = March 1974 | pmid = 10793670 | pmc = 344020 | doi = 10.1093/nar/1.3.331 }}</ref> 

[[Walter Gilbert]], a biochemist, and [[Allan Maxam]], a molecular geneticist, at [[Harvard University|Harvard]] also developed sequencing methods, including one for "DNA sequencing by chemical degradation".<ref name="Maxam77" /><ref>Gilbert, W. [http://nobelprize.org/nobel_prizes/chemistry/laureates/1980/gilbert-lecture.pdf DNA sequencing and gene structure]. Nobel lecture, 8 December 1980.</ref> In 1973, Gilbert and Maxam reported the sequence of 24 basepairs using a method known as wandering-spot analysis.<ref>{{cite journal | vauthors = Gilbert W, Maxam A | title = The Nucleotide Sequence of the lac Operator | journal = Proc. Natl. Acad. Sci. U.S.A. | volume = 70 | issue = 12 | pages = 3581–84 | date = December 1973 | pmid = 4587255 | pmc = 427284 | doi = 10.1073/pnas.70.12.3581 | bibcode = 1973PNAS...70.3581G | doi-access = free }}</ref> Advancements in sequencing were aided by the concurrent development of [[recombinant DNA]] technology, allowing DNA samples to be isolated from sources other than viruses.<ref>{{Cite web |title=Chapter 5: Investigating DNA |url=https://wou.edu:443/chemistry/courses/online-chemistry-textbooks/ch450-and-ch451-biochemistry-defining-life-at-the-molecular-level/chapter-5-investigating-dna/ |access-date=2025-01-31 |website=Chemistry |language=en-US}}</ref>

Two years later in 1975, [[Frederick Sanger]], a biochemist, and [[Alan Coulson]], a genome scientist, developed a method to sequence DNA.<ref>{{Cite journal |last1=Sanger |first1=F. |last2=Coulson |first2=A. R. |date=1975-05-25 |title=A rapid method for determining sequences in DNA by primed synthesis with DNA polymerase |url=https://www.sciencedirect.com/science/article/abs/pii/0022283675902132 |journal=Journal of Molecular Biology |volume=94 |issue=3 |pages=441–448 |doi=10.1016/0022-2836(75)90213-2 |pmid=1100841 |issn=0022-2836|url-access=subscription }}</ref> The [[Sanger sequencing|technique]] known as the "Plus and Minus" method, involved supplying all the components of the DNA but excluding the reaction of one of the four bases needed to complete the DNA.<ref>{{Cite book |last=Cook-Deegan |first=Robert |title=The gene wars: science, politics, and the human genome |date=1995 |publisher=Norton |isbn=978-0-393-31399-4 |edition=1. publ. as a Norton paperback |location=New York NY}}</ref>

In 1976, Gilbert and Maxam, invented a method for rapidly sequencing DNA while at Harvard, known as the Maxam–Gilbert sequencing.<ref>{{Cite web |last=Johnson |first=Carolyn Y. |title=A physicist, biologist, Nobel laureate, CEO, and now, artist |url=https://www.bostonglobe.com/metro/2015/03/12/wally-gilbert-physicist-biologist-nobel-laureate-ceo-and-now-artist/b3OsCNVvHZOYCi48Dz4z6H/story.html |date=2015-03-12 |access-date=2025-02-03 |work=[[The Boston Globe]] |language=en-US}}</ref> The technique involved treating radiolabelled DNA with a chemical and using a polyacrylamide gel to determine the sequence.<ref>Heather JM, Chain B. The sequence of sequencers: The history of sequencing DNA. Genomics. 2016 Jan;107(1):1-8. doi: [https://pmc.ncbi.nlm.nih.gov/articles/PMC4727787/#:~:text=The%20plus%20and%20minus%20technique,before%20the%20next%20missing%20nucleotide 10.1016/j.ygeno.2015.11.003]. Epub 2015 Nov 10. PMID: 26554401; PMCID: PMC4727787.</ref>

In 1977, Sanger then adopted a primer-extension strategy to develop more rapid DNA sequencing methods at the [[Medical Research Council (United Kingdom)|MRC Centre]], [[Cambridge]], UK. This technique was similar to his "Plus and Minus" strategy, however, it was based upon the selective incorporation of chain-terminating dideoxynucleotides (ddNTPs) by [[DNA polymerase]] during in vitro [[DNA replication]].<ref>{{cite book |doi=10.1016/B978-0-12-815499-1.00013-2 |chapter=Nucleic acid analysis in the clinical laboratory |title=Contemporary Practice in Clinical Chemistry |date=2020 |last1=Deharvengt |first1=Sophie J. |last2=Petersen |first2=Lauren M. |last3=Jung |first3=Hou-Sung |last4=Tsongalis |first4=Gregory J. |pages=215–234 |isbn=978-0-12-815499-1 }}</ref><ref>{{cite journal |last1=Heather |first1=James M. |last2=Chain |first2=Benjamin |title=The sequence of sequencers: The history of sequencing DNA |journal=Genomics |date=January 2016 |volume=107 |issue=1 |pages=1–8 |doi=10.1016/j.ygeno.2015.11.003 |pmid=26554401 |pmc=4727787 }}</ref><ref>{{cite journal |last1=Elsayed |first1=Fadwa A. |last2=Grolleman |first2=Judith E. |last3=Ragunathan |first3=Abiramy |last4=Buchanan |first4=Daniel D. |last5=van Wezel |first5=Tom |last6=de Voer |first6=Richarda M. |last7=Boot |first7=Arnoud |last8=Stojovska |first8=Marija Staninova |last9=Mahmood |first9=Khalid |last10=Clendenning |first10=Mark |last11=de Miranda |first11=Noel |last12=Dymerska |first12=Dagmara |last13=Egmond |first13=Demi van |last14=Gallinger |first14=Steven |last15=Georgeson |first15=Peter |last16=Hoogerbrugge |first16=Nicoline |last17=Hopper |first17=John L. |last18=Jansen |first18=Erik A.M. |last19=Jenkins |first19=Mark A. |last20=Joo |first20=Jihoon E. |last21=Kuiper |first21=Roland P. |last22=Ligtenberg |first22=Marjolijn J.L. |last23=Lubinski |first23=Jan |last24=Macrae |first24=Finlay A. |last25=Morreau |first25=Hans |last26=Newcomb |first26=Polly |last27=Nielsen |first27=Maartje |last28=Palles |first28=Claire |last29=Park |first29=Daniel J. |last30=Pope |first30=Bernard J. |last31=Rosty |first31=Christophe |last32=Ruiz Ponte |first32=Clara |last33=Schackert |first33=Hans K. |last34=Sijmons |first34=Rolf H. |last35=Tomlinson |first35=Ian P. |last36=Tops |first36=Carli M.J. |last37=Vreede |first37=Lilian |last38=Walker |first38=Romy |last39=Win |first39=Aung K. |title=Monoallelic NTHL1 Loss-of-Function Variants and Risk of Polyposis and Colorectal Cancer |journal=Gastroenterology |date=December 2020 |volume=159 |issue=6 |pages=2241–2243.e6 |doi=10.1053/j.gastro.2020.08.042 |pmid=32860789 |pmc=7899696 |hdl=2066/228713 |hdl-access=free }}</ref> Sanger published this method in the same year. <ref name="Sanger1977" />