The location of the CFTR gene on chromosome 7 In many localities all newborns are screened for cystic fibrosis 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 cystic fibrosis 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 CFTR is dysfunctional; the person is then diagnosed with cystic fibrosis. Genetic testing is also available to identify the CFTR mutations typically associated with cystic fibrosis. Many laboratories can test for the 30–96 most common CFTR mutations, which can identify over 90% of people with cystic fibrosis. People with CF have less thiocyanate and hypothiocyanite in their saliva and mucus (Banfi et al.). In the case of milder forms of CF, transepithelial potential difference measurements can be helpful. CF can also be diagnosed by identification of mutations in the CFTR 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 CFTR gene (carriers) or, in rare instances, in individuals with two normal copies of the CFTR gene. Due to these false positives, CF 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 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. Because 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 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. , 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 CF. 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 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 higher economic benefit.
medical cause of Bronchiectasis
medical cause of Bronchiolitis
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medical cause of Acute bronchitis
symptom of Idiopathic pulmonary fibrosis
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medical cause of Bronchiolitis obliterans