Final answer:
To diagnose cystic fibrosis, a sweat test is used to examine the levels of sodium and chloride present in perspiration. Cystic fibrosis is caused by a mutation in the CFTR gene, which impairs the salt transport and results in the accumulation of thick mucus. Elevated sweat chloride levels, which are not influenced by temperature, serve as a key diagnostic indicator of the condition.
Step-by-step explanation:
To diagnose cystic fibrosis, a condition in which increased levels of sodium and chloride are present in perspiration, a sweat test is used. Cystic fibrosis is a genetic noninfectious disease caused by a mutation in the CFTR gene, which leads to the production of a dysfunctional protein affecting the transport of sodium chloride in and out of cells. This results in the production of thick and sticky mucus, particularly noticeable in the lungs and digestive system, which can lead to respiratory infections and malabsorption issues.
The symptoms of cystic fibrosis are due to a malfunctioning membrane ion channel known as the cystic fibrosis transmembrane conductance regulator or CFTR. In healthy individuals, the CFTR protein behaves as an integral membrane protein transporting Cl- ions out of cells. However, in people with cystic fibrosis, the CFTR gene mutation causes a defective channel protein that fails to integrate properly into the membrane, impairing ion transport and leading to hyperchloremia, which is high levels of chloride, notably in sweat.
It is important to note that while temperature can affect the amount of sodium and chloride lost through perspiration, the elevated levels found in the sweat of those with cystic fibrosis are due to the underlying genetic condition and not environmental factors. Therefore, analysis of sweat chloride levels is a key diagnostic tool for identifying cystic fibrosis.