Cystic fibrosis (CF) is a genetic disorder inherited in an autosomal recessive manner, which means that both parents must carry the faulty gene for their child to be affected by the condition.

Specifically, CF arises from mutations in the CFTR gene, which encodes a protein that regulates the movement of salt and water in and out of cells. When this gene is faulty, it results in the production of thick, sticky mucus that accumulates in various organs, particularly the lungs and digestive system.

Each individual possesses two copies of the CFTR gene, one inherited from each parent. When both parents are carriers of a defective CFTR gene, the probabilities for their offspring are as follows:

• There is a 25% chance that the child will inherit two faulty genes and thus have cystic fibrosis.
• There is a 50% chance that the child will inherit one faulty gene and be a carrier of the condition.
• There is a 25% chance that the child will inherit two normal genes, meaning they will neither have cystic fibrosis nor be a carrier.

To clarify, if a child inherits one faulty CFTR gene, they will be a carrier but will not exhibit symptoms of the disease. Conversely, if they inherit two faulty genes, they will develop cystic fibrosis.

It is crucial to understand that being a carrier of CF, which means possessing one faulty CFTR gene, does not negatively impact an individual’s health. However, carriers have the potential to pass the faulty gene to their offspring. For individuals who are carriers or have a family history of cystic fibrosis, genetic counseling can offer valuable information and guidance.