Editing Cystic fibrosis (section)

===Carriers===
Up to one in 25 individuals of Northern European ancestry is considered a [[genetic carrier]].<ref name="Edwards" /> The disease appears only when two of these carriers have children, as each pregnancy between them has a 25% chance of producing a child with the disease. Although only about one of every 3,000 newborns of the affected ancestry has CF, since the CFTR gene's discovery in 1989, over 2,000 variants have been identified, but only about 700 of these have been recognized as responsible for causing CF.<ref name="pmid37699417">{{cite journal | vauthors = Graeber SY, Mall MA | title = The future of cystic fibrosis treatment: from disease mechanisms to novel therapeutic approaches | journal = Lancet | volume = 402 | issue = 10408 | pages = 1185–1198 | date = September 2023 | pmid = 37699417 | doi = 10.1016/s0140-6736(23)01608-2 | s2cid = 261623275 }}</ref> Current tests look for the most common mutations.<ref name="Edwards">{{cite journal | vauthors = Edwards QT, Seibert D, Macri C, Covington C, Tilghman J | title = Assessing ethnicity in preconception counseling: genetics--what nurse practitioners need to know | journal = Journal of the American Academy of Nurse Practitioners | volume = 16 | issue = 11 | pages = 472–480 | date = November 2004 | pmid = 15617360 | doi = 10.1111/j.1745-7599.2004.tb00426.x | s2cid = 7644129 }}</ref>

The mutant alleles screened by the test vary according to a person's ethnic group or by the occurrence of CF already in the family. More than 10 million Americans, including one in 25 white Americans, are carriers of one mutant allele of the CF gene. [[Cystic fibrosis and race|CF is present in other races]], though not as frequently as in white individuals. About one in 46 Hispanic Americans, one in 65 African Americans, and one in 90 Asian Americans carry a mutation of the CF gene.<ref name="Edwards"/>