Cystic fibrosis is an inherited disorder, mostly of young children. Sometimes the disease is not diagnosed until adolescence or adulthood. People with cystic fibrosis secrete very thick mucus from the windpipe, or tracheobronchial glands. They also have abnormal secretions of sweat and saliva. The pancreas may release enzymes improperly, a condition called pancreatic insufficiency. The lungs have changes similar to those in emphysema.

Different people have different levels of abnormalities in cystic fibrosis. Some people are very ill when they are quite young. Others can live many years with mild abnormalities. Half of males with cystic fibrosis now live to be over 30 years old. Half of females with cystic fibrosis survive beyond 28 years.

What is going on in the body?

Since the abnormally thick mucus prevents proper clearing of sputum and bacteria from the lungs, the person's lungs become chronically infected. The mucus blocks the secretion of enzymes used for digesting foods from the pancreas.

What are the causes and risks of the disease?

Cystic fibrosis is the most common serious genetic disease among Caucasian children. It occurs in about 1 of every 2,500 live births. The disease almost always occurs in Caucasians, and is equally common in males and females. It is chiefly a disease of infants and children, but more adult cases are being diagnosed.

Cystic fibrosis is an autosomal recessive trait. This means that both parents must pass on an abnormal gene for the child to be affected. One in 25 adults carries one copy of the cystic fibrosis gene. If both parents carry the gene, each child has a 25% risk of cystic fibrosis. If one parent has gene with no history of cystic fibrosis and the other parent has the disease, there is a 50% chance of the child being affected.