Cystic fibrosis (CF) is a genetic disorder caused by mutations in the CFTR (cystic fibrosis transmembrane conductance regulator) gene. The CFTR gene encodes a protein that plays a critical role in the function of sweat glands, the respiratory system, the digestive system, and other organs. Mutations in this gene lead to the production of a defective or non-functional CFTR protein, which results in the characteristic symptoms and complications of CF.
Here’s how it works:
- Normal CFTR Protein Function: In individuals without CF, the CFTR protein regulates the movement of chloride ions and water in and out of cells lining the airways, sweat ducts, and other mucous-producing organs. This helps maintain the balance of mucus, salt, and water in these tissues.
- Mutated CFTR Protein: In individuals with CF, mutations in the CFTR gene lead to a dysfunctional CFTR protein. As a result, the chloride ion channels don’t work properly. This disrupts the normal flow of salt and water in and out of cells, causing several problems:
- Thick, sticky mucus: The cells lining the airways produce thick, sticky mucus that can clog the airways, making it difficult to breathe and creating a breeding ground for bacteria, leading to frequent lung infections.
- Digestive issues: In the digestive system, thickened mucus can block the pancreatic ducts, preventing digestive enzymes from reaching the small intestine. This leads to poor digestion and nutrient absorption, as well as intestinal blockages.
- Symptoms: The accumulation of thick mucus in the respiratory and digestive systems is at the root of the symptoms associated with CF, including respiratory problems, frequent lung infections, digestive issues, and other complications.
It’s important to note that CF is an autosomal recessive genetic disorder, which means that a person must inherit two defective CFTR gene copies (one from each parent) to develop the condition. Individuals who inherit one normal and one mutated CFTR gene are carriers of CF but typically do not show symptoms of the disease.
The specific CFTR gene mutations can vary from person to person, and there are many different mutations associated with CF. Some mutations result in more severe symptoms than others. Genetic testing can identify which CFTR gene mutations a person has, which is useful for diagnosis and understanding the potential severity of the condition.