Editing Cystic fibrosis (section)

===Prenatal===
Women who are [[pregnant]] or couples planning a pregnancy can have themselves tested for the ''CFTR'' gene mutations to determine the risk that their child will be born with CF. Testing is typically performed first on one or both parents and, if the risk of CF is high, testing on the fetus is performed. The [[American College of Obstetricians and Gynecologists]] recommends all people thinking of becoming pregnant be tested to see if they are a carrier.<ref name="American College of Obstetricians and Gynecologists-2017">{{cite web|url=https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2017/03/carrier-screening-in-the-age-of-genomic-medicine |number=690 |title=Carrier Screening in the Age of Genomic Medicine|date=2017|website=American College of Obstetricians and Gynecologists|url-status=live|archive-url=https://web.archive.org/web/20170225052721/http://www.acog.org/Resources-And-Publications/Committee-Opinions/Committee-on-Genetics/Carrier-Screening-in-the-Age-of-Genomic-Medicine|archive-date=25 February 2017|access-date=22 February 2020}}</ref>

Because the development of CF in the fetus requires each parent to pass on a mutated copy of the ''CFTR'' gene and because CF testing is expensive, testing is often performed initially on one parent. If testing shows that the parent is a ''CFTR'' gene mutation carrier, the other parent is tested to calculate the risk that their children will have CF. CF can result from more than a thousand different mutations.<ref name="Lancet2016">{{cite journal | vauthors = Elborn JS | title = Cystic fibrosis | journal = Lancet | volume = 388 | issue = 10059 | pages = 2519–2531 | date = November 2016 | pmid = 27140670 | doi = 10.1016/S0140-6736(16)00576-6 | s2cid = 20948144 }}</ref> {{as of|2016}}, typically only the most common mutations are tested for, such as ΔF508.<ref name=Lancet2016/> Most commercially available tests look for 32 or fewer different mutations. If a family has a known uncommon mutation, specific screening for that mutation can be performed. Because not all known mutations are found on current tests, a negative screen does not guarantee that a child will not have CF.<ref name="pmid2014829">{{cite journal | vauthors = Elias S, Annas GJ, Simpson JL | title = Carrier screening for cystic fibrosis: implications for obstetric and gynecologic practice | journal = American Journal of Obstetrics and Gynecology | volume = 164 | issue = 4 | pages = 1077–1083 | date = April 1991 | pmid = 2014829 | doi = 10.1016/0002-9378(91)90589-j }}</ref>

During pregnancy, testing can be performed on the placenta ([[chorionic villus sampling]]) or the fluid around the fetus ([[amniocentesis]]). However, chorionic villus sampling has a risk of fetal death of one in 100 and amniocentesis of one in 200;<ref name="pmid2423826">{{cite journal | vauthors = Tabor A, Philip J, Madsen M, Bang J, Obel EB, Nørgaard-Pedersen B | title = Randomised controlled trial of genetic amniocentesis in 4606 low-risk women | journal = Lancet | volume = 1 | issue = 8493 | pages = 1287–1293 | date = June 1986 | pmid = 2423826 | doi = 10.1016/S0140-6736(86)91218-3 | s2cid = 31237495 }}</ref> a recent study has indicated this may be much lower, about one in 1,600.<ref name="pmid17077226">{{cite journal | vauthors = Eddleman KA, Malone FD, Sullivan L, Dukes K, Berkowitz RL, Kharbutli Y, Porter TF, Luthy DA, Comstock CH, Saade GR, Klugman S, Dugoff L, Craigo SD, Timor-Tritsch IE, Carr SR, Wolfe HM, D'Alton ME | title = Pregnancy loss rates after midtrimester amniocentesis | journal = Obstetrics and Gynecology | volume = 108 | issue = 5 | pages = 1067–1072 | date = November 2006 | pmid = 17077226 | doi = 10.1097/01.AOG.0000240135.13594.07 | s2cid = 19081825 }}</ref>

Economically, for carrier couples of cystic fibrosis, when comparing [[preimplantation genetic diagnosis]] (PGD) with natural conception (NC) followed by prenatal testing and abortion of affected pregnancies, PGD provides net economic benefits up to a maternal age around 40 years, after which NC, prenatal testing, and abortion have a higher economic benefit.<ref name="pmid19439290">{{cite journal | vauthors = Davis LB, Champion SJ, Fair SO, Baker VL, Garber AM | title = A cost-benefit analysis of preimplantation genetic diagnosis for carrier couples of cystic fibrosis | journal = Fertility and Sterility | volume = 93 | issue = 6 | pages = 1793–1804 | date = April 2010 | pmid = 19439290 | doi = 10.1016/j.fertnstert.2008.12.053 | doi-access = free }}</ref>