Editing Cystic fibrosis (section)

===Gene modulators===
Several small molecules that aim at compensating various mutations of the ''CFTR'' gene are under development. CFTR [[Gene modulation|modulator therapies]] has been used instead of other types of genetic therapies. These therapies focus on the expression of a genetic mutation instead of the mutated gene itself. Modulators are split into two classes: potentiators and correctors. Potentiators act on the CFTR ion channels that are embedded in the cell membrane, and these drugs help open up the channel to allow transmembrane flow. Correctors are meant to assist in the transportation of nascent proteins, proteins that are formed by ribosomes before it is morphed into a specific shape, to the cell surface to be implemented into the cell membrane.<ref name=Ram2019>{{cite journal | vauthors = Ramsey BW, Downey GP, Goss CH | title = Update in Cystic Fibrosis 2018 | journal = American Journal of Respiratory and Critical Care Medicine | volume = 199 | issue = 10 | pages = 1188–1194 | date = May 2019 | pmid = 30917288 | pmc = 6519861 | doi = 10.1164/rccm.201902-0310UP | id = {{ProQuest|2230820891}} }}</ref>

Most target the transcription stage of genetic expression. One approach has been to try and develop medication that get the ribosome to overcome the [[stop codon]] and produce a full-length CFTR protein. About 10% of CF results from a premature stop codon in the DNA, leading to early termination of protein synthesis and truncated proteins. These drugs target [[nonsense mutation]]s such as G542X, which consists of the amino acid [[glycine]] in position 542 being replaced by a stop codon. Aminoglycoside antibiotics interfere with protein synthesis and error correction. In some cases, they can cause the cell to overcome a premature stop codon by inserting a random amino acid, thereby allowing the expression of a full-length protein. Future research for these modulators is focused on the cellular targets that can be affected by a change in a gene's expression. Otherwise, genetic therapy will be used as a treatment when modulator therapies do not work given that 10% of people with cystic fibrosis are not affected by these drugs.<ref name="pmid20818846">{{cite journal | vauthors = Dietz HC | title = New therapeutic approaches to mendelian disorders | journal = The New England Journal of Medicine | volume = 363 | issue = 9 | pages = 852–863 | date = August 2010 | pmid = 20818846 | doi = 10.1056/NEJMra0907180 | s2cid = 5809127 | doi-access = free }} Free full text</ref>

[[Elexacaftor/ivacaftor/tezacaftor]] was approved in the United States in 2019 for cystic fibrosis.<ref name=FDA2019Tx>{{Cite web|url=https://www.fda.gov/news-events/press-announcements/fda-approves-new-breakthrough-therapy-cystic-fibrosis|title=FDA approves new breakthrough therapy for cystic fibrosis | author = Office of the Commissioner |date=24 October 2019|website=FDA|language=en|access-date=13 November 2019}}</ref> This combination of previously developed medicines can treat up to 90% of people with cystic fibrosis.<ref name=Ram2019/><ref name=FDA2019Tx/> This medication restores some effectiveness of the CFTR protein so that it can work as an ion channel on the cell's surface.<ref name="Cystic Fibrosis Foundation-2">{{Cite web|url=https://www.cff.org/Life-With-CF/Treatments-and-Therapies/Medications/CFTR-Modulator-Therapies/|title=CFTR Modulator Therapies | location = Bethesda, Md. | publisher = Cystic Fibrosis Foundation |language=en|access-date=13 November 2019}}</ref>