Editing Cystic fibrosis (section)

===Gene therapy===
[[Gene therapy]] has been explored as a potential cure for CF. Results from clinical trials have shown limited success {{as of|2016|lc=y}}, and using gene therapy as routine therapy is not suggested.<ref name="pmid27314455">{{cite journal | vauthors = Lee TW, Southern KW, Perry LA, Penny-Dimri JC, Aslam AA | title = Topical cystic fibrosis transmembrane conductance regulator gene replacement for cystic fibrosis-related lung disease | journal = The Cochrane Database of Systematic Reviews | volume = 2016 | issue = 6 | pages = CD005599 | date = June 2016 | pmid = 27314455 | pmc = 8682957 | doi = 10.1002/14651858.CD005599.pub5 | veditors = Southern KW }}</ref> A small study published in 2015 found a small benefit.<ref name="pmid26149841">{{cite journal | vauthors = Alton EW, Armstrong DK, Ashby D, Bayfield KJ, Bilton D, Bloomfield EV, Boyd AC, Brand J, Buchan R, Calcedo R, Carvelli P, Chan M, Cheng SH, Collie DD, Cunningham S, Davidson HE, Davies G, Davies JC, Davies LA, Dewar MH, Doherty A, Donovan J, Dwyer NS, Elgmati HI, Featherstone RF, Gavino J, Gea-Sorli S, Geddes DM, Gibson JS, Gill DR, Greening AP, Griesenbach U, Hansell DM, Harman K, Higgins TE, Hodges SL, Hyde SC, Hyndman L, Innes JA, Jacob J, Jones N, Keogh BF, Limberis MP, Lloyd-Evans P, Maclean AW, Manvell MC, McCormick D, McGovern M, McLachlan G, Meng C, Montero MA, Milligan H, Moyce LJ, Murray GD, Nicholson AG, Osadolor T, Parra-Leiton J, Porteous DJ, Pringle IA, Punch EK, Pytel KM, Quittner AL, Rivellini G, Saunders CJ, Scheule RK, Sheard S, Simmonds NJ, Smith K, Smith SN, Soussi N, Soussi S, Spearing EJ, Stevenson BJ, Sumner-Jones SG, Turkkila M, Ureta RP, Waller MD, Wasowicz MY, Wilson JM, Wolstenholme-Hogg P | title = Repeated nebulisation of non-viral CFTR gene therapy in patients with cystic fibrosis: a randomised, double-blind, placebo-controlled, phase 2b trial | journal = The Lancet. Respiratory Medicine | volume = 3 | issue = 9 | pages = 684–691 | date = September 2015 | pmid = 26149841 | pmc = 4673100 | doi = 10.1016/S2213-2600(15)00245-3 }}</ref>

The focus of much CF gene therapy research is aimed at trying to place a normal copy of the ''CFTR'' gene into affected cells. Transferring the normal ''CFTR'' gene into the affected epithelial cells would result in the production of functional CFTR protein in all target cells, without adverse reactions or an inflammation response; this is known as somatic cell therapy. To prevent the lung manifestations of CF, only 5–10% of the normal amount of CFTR gene expression is needed.<ref name="pmid12397022">{{cite journal | vauthors = Ramalho AS, Beck S, Meyer M, Penque D, Cutting GR, Amaral MD | title = Five percent of normal cystic fibrosis transmembrane conductance regulator mRNA ameliorates the severity of pulmonary disease in cystic fibrosis | journal = American Journal of Respiratory Cell and Molecular Biology | volume = 27 | issue = 5 | pages = 619–627 | date = November 2002 | pmid = 12397022 | doi = 10.1165/rcmb.2001-0004oc | s2cid = 8714332 }}</ref> Multiple approaches have been tested for gene transfer, such as liposomes and viral vectors in animal models and clinical trials. However, both methods were found to be relatively inefficient treatment options,<ref name="pmid16296753">{{cite journal | vauthors = Tate S, Elborn S | title = Progress towards gene therapy for cystic fibrosis | journal = Expert Opinion on Drug Delivery | volume = 2 | issue = 2 | pages = 269–280 | date = March 2005 | pmid = 16296753 | doi = 10.1517/17425247.2.2.269 | s2cid = 30948229 }}</ref> mainly because very few cells take up the vector and express the gene, so the treatment has little effect. Additionally, problems have been noted in cDNA recombination, such that the gene introduced by the treatment is rendered unusable.<ref name="Online Mendelian Inheritance in Man">{{OMIM|219700|CYSTIC FIBROSIS; CF}}</ref> There has been a functional repair in culture of CFTR by CRISPR/Cas9 in intestinal stem cell organoids of cystic fibrosis patients.<ref name="pmid24315439">{{cite journal | vauthors = Schwank G, Koo BK, Sasselli V, Dekkers JF, Heo I, Demircan T, Sasaki N, Boymans S, Cuppen E, van der Ent CK, Nieuwenhuis EE, Beekman JM, Clevers H | title = Functional repair of CFTR by CRISPR/Cas9 in intestinal stem cell organoids of cystic fibrosis patients | journal = Cell Stem Cell | volume = 13 | issue = 6 | pages = 653–658 | date = December 2013 | pmid = 24315439 | doi = 10.1016/j.stem.2013.11.002 | doi-access = free }}</ref>