Cystic Fibrosis

Cystic fibrosis (CF) is a genetic disorder that particularly affects the lungs and digestive system and makes kids who have it more vulnerable to repeated lung infections. Now, thanks to high-tech medical advances in drug therapy and genetics, children born with CF can look forward to longer and more comfortable lives. In the last 10 years, research into all aspects of CF has helped doctors to understand the illness better and to develop new therapies. Ongoing research may someday lead to a cure.

What Is Cystic Fibrosis?

Currently affecting more than 30,000 children and young adults in the United States, cystic fibrosis makes kids sick by disrupting the normal function of epithelial cells — cells that make up the sweat glands in the skin and that also line passageways inside the lungs, liver, pancreas, and digestive and reproductive systems.

The inherited CF gene directs the body's epithelial cells to produce a defective form of a protein called CFTR (or cystic fibrosis transmembrane conductance regulator) found in cells that line the lungs, digestive tract, sweat glands, and genitourinary system. When the CFTR protein is defective, epithelial cells can't regulate the way chloride (part of the salt called sodium chloride) passes across cell membranes. This disrupts the essential balance of salt and water needed to maintain a normal thin coating of fluid and mucus inside the lungs, pancreas, and passageways in other organs. The mucus becomes thick, sticky, and hard to move.

Normally, mucus in the lungs traps germs, which are then cleared out of the lungs. But in CF, the thick, sticky mucus and the germs it has trapped remain in the lungs, which become infected.

In the pancreas, thick mucus blocks the channels that would normally carry important enzymes to the intestines to digest foods. When this happens, the body can't process or absorb nutrients properly, especially fats. Kids with CF have problems gaining weight, even with a normal diet and a good appetite.

A Family's Risk for CF

Humans have 23 pairs of chromosomes made of the inherited genetic chemical deoxyribonucleic acid (DNA). The CF gene is found on chromosome number 7. It takes two copies of a CF gene — one inherited from each parent — for a child to show symptoms of CF. People born with only one CF gene (inherited from only one parent) and one normal gene are CF carriers. CF carriers do not show CF symptoms themselves, but can pass the problem CF gene to their children. Scientists estimate that about 12 million Americans are currently CF carriers. If two CF carriers have a child, there is a 1 in 4 chance that the child will have CF.

Almost 1,400 different mutations of the CF gene can lead to cystic fibrosis (some mutations cause milder symptoms than others). About 70% of people with CF have the disease because they inherited the mutant gene Delta F508 from both of their parents. This can be detected by genetic testing, which can be done in kids both before and after birth and in adults thinking about starting or enlarging their families.