People affected by cystic fibrosis usually have an increased amount of salt in their sweat so diagnosis can be made by a sweat test. Alternatively, a test for the presence of specific enzymes in the intestine can be performed and testing for cystic fibrosis is routinely taken in newborn babies by checking for elevated levels of immunoreactive trypsinogen (IRT) in a blood sample. Genetic testing to identify mutations in the CFTR gene is also commonly used.
More than 1900 mutations have been identified in the CFTR gene. Over 500 of these mutations are known to cause cystic fibrosis. The severity of cystic fibrosis symptoms vary depending on the type of the mutation in the CFTR gene.
DeltaF508 is the most common mutation in cystic fibrosis cases across all ethnicities, but other mutations vary between different populations. The American College of Medical Genetics recommends screening for 23 mutations in the CFTR gene. The cystic fibrosis DNA test offered here tests for these 23 mutations, along with 16 other mutations. Nine mutations in the panel offered from this laboratory cause approximately 99% of all cases of cystic fibrosis in Ashkenazi Jewish individuals.
Prenatal testing (during pregnancy) and carrier testing (of both parents) is available and is recommended for those at an increased risk due to ethnicity, symptoms or a family history.
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Castellani C, Cuppens H, Macek M et al. (2008). Consensus on the use and interpretation of cystic fibrosis mutation analysis in clinical practice. Journal of Cystic Fibrosis. 7: 179-196.
Kornreich R, Ekstein J, Edelmann L, Desnick RJ (2004). Premarital and prenatal screening for cystic fibrosis: Experience in the Ashkenazi Jewish population. Genetics in Medicine 6: 415–420.