Question

How is cystic fibrosis detected? Can the diagnostic method be used for the detection of other genetic disorders? Explain your answer

Short answer

Cystic fibrosis is detected through methods like newborn screening, sweat tests, and genetic testing. Newborn screening measures the level of immunoreactive trypsinogen (IRT) in a newborn's blood, but it isn't specific enough for other genetic disorders. Sweat tests, on the other hand, specifically measure chloride concentrations in sweat and are exclusive to cystic fibrosis. Genetic testing analyzes DNA for mutations in the CFTR gene and can be used to detect other genetic disorders by targeting the associated genes and markers.

Step-by-step solution

1. Newborn Screening

Newborn screening is a test done on newborn infants to detect various genetic disorders, including cystic fibrosis. This test typically involves taking a blood sample from the heel of the newborn and measuring the level of immunoreactive trypsinogen (IRT) in the blood. Elevated IRT levels could indicate cystic fibrosis since the digestive system in people with CF produces more IRT than usual. With only the IRT test, it's not specific enough for detecting other genetic disorders, but other aspects of newborn screening can identify different conditions.

2. Sweat Test

The sweat test is a common diagnostic tool for confirming cystic fibrosis. This method measures the amount of chloride in the sweat. People with CF have a higher concentration of chloride in their sweat since the faulty CFTR protein is unable to regulate chloride and sodium transport across the cells, leading to the accumulation of salty sweat. Since this test specifically detects CF symptoms based on chloride concentration, it cannot be used to detect other genetic disorders.

3. Genetic Testing

Genetic testing for cystic fibrosis involves analyzing the DNA from blood or saliva samples to identify mutations in the CFTR gene. This can confirm a CF diagnosis and provide information about the specific CF-causing mutations. Genetic testing can indeed be used for detecting other genetic disorders, as long as the specific gene/s associated with those disorders are known and targeted during the test. In such cases, the DNA will be analyzed for mutations in different genes instead of the CFTR gene.

4. Conclusion

While cystic fibrosis can be detected using various methods such as newborn screening, sweat tests, and genetic testing, not all of these methods can be used for detecting other genetic disorders. Sweat tests are specifically tailored to measure chloride levels related to cystic fibrosis symptoms, rendering them unsuitable for detecting other conditions. On the other hand, newborn screening and genetic testing can be applied to a broader range of genetic disorders, as long as the associated genes and markers are targeted during the tests.