Cystic fibrosis is transmitted to a child when both parents carry the recessive gene but do not have the disease. When such a couple has children, there is a 25 percent chance that one of their children will develop cystic fibrosis; there is a 50 percent chance that the child will carry the gene, but will not have the disease; and a 25 percent chance that the child will be totally unaffected.
Cystic fibrosis is the most common fatal hereditary disorder for Caucasians in the U.S. About 1 in 2500 Caucasians are affected, and more than 10 million people (one in 31 Americans; one in 28 Caucasians) is an unknowing, symptomless carrier of the defective gene.
The average lifespan of a person affected with CF is between 28 and 30 years of age. As with any "average" this means that some with this disease now live well beyond this age. With the introduction of medications and drainage procedures, children with CF, who years ago would have died before reaching adulthood, are now often living into mid-adulthood and beyond. The cause of death in CF patients is usually respiratory tract infections or respiratory distress, coupled with enlargement of the right side of the heart (cor pulmonale).