Editing Chromosomal translocation (section)

==History==
Chromosomal translocations – in which a segment of one chromosome breaks off and attaches to another – were first observed in the early 20th century. In 1916, American zoologist William R. B. Robertson documented a chromosomal fusion in grasshoppers (now known as a [[Robertsonian translocation]]).<ref name=":19">{{Cite journal |last1=HROMAS |first1=ROBERT |last2=WILLIAMSON |first2=ELIZABETH |last3=LEE |first3=SUK-HEE |last4=NICKOLOFF |first4=JAC |date=2016 |title=Preventing the Chromosomal Translocations That Cause Cancer |journal=Transactions of the American Clinical and Climatological Association |language=en |volume=127 |pages=176–195 |pmc=5216476 |pmid=28066052}}</ref> In 1938, Karl Sax demonstrated that X-ray irradiation could induce chromosomal translocations, observing radiation-induced fusions between different chromosomes in plant cells.<ref name=":19" /> During the 1940s, Barbara McClintock’s maize cytogenetics experiments revealed the breakage–fusion–bridge cycle of chromosomes, further illuminating mechanisms of chromosomal rearrangement.<ref name=":5">{{Cite journal |last=Oviedo de Valeria |first=Jenny |date=1994-08-02 |title=Problemas multiplicativos tip transformacion lineal: tareas de compra y venta |url=https://doi.org/10.24844/em0602.06 |journal=Educación matemática |volume=6 |issue=2 |pages=73–86 |doi=10.24844/em0602.06 |issn=2448-8089}}</ref> A major breakthrough came in 1960 with the discovery of the [[Philadelphia chromosome]] in [[chronic myelogenous leukemia]] – the first consistent chromosomal abnormality linked to a human cancer.{{citation needed|date=March 2025}} In 1973, Janet Rowley identified the Philadelphia chromosome as a translocation between chromosomes 9 and 22, definitively linking a specific chromosomal translocation to leukemia <ref>{{Cite journal |last=Rowley |first=Janet D. |date=June 1973 |title=A New Consistent Chromosomal Abnormality in Chronic Myelogenous Leukaemia identified by Quinacrine Fluorescence and Giemsa Staining |url=https://www.nature.com/articles/243290a0 |journal=Nature |language=en |volume=243 |issue=5405 |pages=290–293 |bibcode=1973Natur.243..290R |doi=10.1038/243290a0 |issn=1476-4687|url-access=subscription }}</ref>

In subsequent decades, technological advances greatly enhanced the detection and understanding of translocations. The introduction of chromosome banding techniques in the 1970s (e.g. [[Q-banding]] and [[G banding|G-banding]]) allowed more precise identification of individual chromosomes and their abnormalities in karyotypes.<ref name=":6">{{Cite web |last=Case |first=Sean |date=2020-07-27 |title=History and Evolution of Cytogenetics |url=https://www.thermofisher.com/blog/behindthebench/history-and-evolution-of-cytogenetics/#:~:text=Starting%20in%20the%201970s,%20fluorescent,These%20staining |access-date=2025-03-13 |website=Behind the Bench |language=en-US}}</ref> The development of fluorescence in situ hybridization ([[Fluorescence in situ hybridization|FISH]]) in the early 1980s enabled researchers to label specific DNA sequences with fluorescent probes on chromosomes, dramatically improving the mapping of translocation breakpoints.<ref name=":6" /> In the 21st century, high-throughput DNA sequencing (such as whole-genome sequencing) has made it possible to detect translocations at single-nucleotide resolution, leading to the discovery of numerous previously undetected translocations across different cancers and genetic disorders.<ref name=":5" />