The location of the<unk> TR gene on chromosome 7 In many localities all newborns are screened for<unk>  within the first few days of life, typically by blood test for high levels of immunoreactive trypsinogen. Newborns with positive tests or those who are otherwise suspected of having<unk>  based on symptoms or family history, then undergo a sweat test. An electric current is used to drive pilocarpine into the skin, stimulating sweating. The sweat is collected and analyzed for salt levels. Having unusually high levels of chloride in the sweat suggests<unk> TR is dysfunctional; the person is then diagnosed with<unk> . Genetic testing is also available to identify the<unk> TR mutations typically associated with<unk> . Many laboratories can test for the 30–96 most common<unk> TR mutations, which can identify over 90% of people with<unk> . People with<unk>  have less thiocyanate and hypothiocyanite in their saliva and mucus (Banfi et al.). In the case of milder forms of<unk> , transepithelial potential difference measurements can be helpful.<unk>  can also be diagnosed by identification of mutations in the<unk> TR gene. In many cases, a parent makes the diagnosis because the infant tastes salty. Immunoreactive trypsinogen levels can be increased in individuals who have a single mutated copy of the<unk> TR gene (carriers) or, in rare instances, in individuals with two normal copies of the<unk> TR gene. Due to these false positives,<unk>  screening in newborns can be controversial. By 2010 every US state had instituted newborn screening programs and as of 2016, 21 European countries had programs in at least some regions. Prenatal Women who are pregnant or couples planning a pregnancy can have themselves tested for the<unk> TR gene mutations to determine the risk that their child will be born with<unk> . Testing is typically performed first on one or both parents and, if the risk of<unk>  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. Because development of<unk>  in the fetus requires each parent to pass on a mutated copy of the<unk> TR gene and because<unk>  testing is expensive, testing is often performed initially on one parent. If testing shows that parent is a<unk> TR gene mutation carrier, the other parent is tested to calculate the risk that their children will have<unk> .<unk>  can result from more than a thousand different mutations. , typically only the most common mutations are tested for, such as ΔF508 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<unk> . 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; a recent study has indicated this may be much lower, about one in 1,600. Economically, for carrier couples of<unk> , 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 higher economic benefit.
Cystic fibrosis
Bronchiolitis
Primary ciliary dyskinesia
Coeliac disease
Adventitial cystic disease
Johanson–Blizzard syndrome
Yokkaichi asthma
Alpha-1 antitrypsin deficiency