Back to Home What is the cause of Cystic Fibrosis? HOW IS CYSTIC FIBROSIS INHERITED? Cystic Fibrosis is a inherited disease and is not contagious. A person gets Cystic Fibrosis when he or she inherits two mutated CFTR genes (as their called) one from each parent. The presence of two mutant genes (g) is needed for Cystic Fibrosis to appear. Each parent carries one defective gene (g) and one normal gene (G). The single normal gene is sufficient for normal function of the mucus glands, and the parents are therefore Cystic Fibrosis-free. Each child has a 25 percent risk of inheriting two defective genes and getting Cystic Fibrosis, a 25 percent chance of inheriting two normal genes, and a 50 percent chance of being an unaffected carrier like the parents. Back to Home This web site is intended for your own informational purposes only. No person or entity associated with this web site purports to be engaging in the practice of medicine through these web pages. The information you obtain is not intended as a substitute for the advice of a physician or other health care professional. If you have an illness or medical problem, contact your health provider.