Understanding Cystic Fibrosis

What is Cystic Fibrosis?

Cystic fibrosis (CF) is an inherited disease that causes thick, sticky mucus to form in the lungs, pancreas and other organs. In the lungs, this mucus blocks the airways, causing lung damage and making it hard to breathe. In the pancreas, it clogs the pathways leading to the digestive system, interfering with proper digestion.

Cystic fibrosis is the second most common inherited disorder occurring in childhood in the United States, behind sickle cell anemia. More than 10 million Americans carry the defective cystic fibrosis gene without knowing it.

Approximately 30,000 people in the United States have CF. About 1,000 new cases of cystic fibrosis are diagnosed each year.

How Serious is Cystic Fibrosis?

The thick, sticky mucus produced by a person with CF blocks the airways in the lungs. This makes breathing difficult. Bacteria grows in the mucus, leading to life-threatening lung infections that can damage the lungs. The mucus also clogs the pancreas, which prevents normal digestion and leads to malnutrition. People with CF are also at increased risk of diabetes and osteoporosis.

In some people with CF, the disease begins in childhood. Others have a milder form of the disease and don't start getting sick until they are teenagers or adults. Lung function often starts declining in childhood, eventually leading to severe breathing problems. The most common cause of death in people with CF is respiratory failure.

The life expectancy of a person with CF is rising. Today some people with CF live into their 30s, 40s and beyond. The median age of survival—the age by which half of CF patients would be expected to survive—rose to 37.4 in 2008, up from 32 in 2000 and 25 in 1985.

What Causes Cystic Fibrosis?

A person must inherit two defective CF genes—one from each parent—to have CF.

Each time two carriers of the defective gene conceive, there is a:

  • 25 percent chance that their child will have cystic fibrosis
  • 50 percent chance that the child will inherit one defective gene and be a carrier but not have the disease
  • 25 percent chance that the child will not have the gene at all