Cystic fibrosis appears in children who inherit both genes from the disease, one from each parent. A parent whose cells have only one gene can not be affected by cystic fibrosis. But when two people with this gene each have children, one or more of their children can inherit both genes and be born with cystic fibrosis.
In this case, for each birth, there is a 25% chance of cystic fibrosis, a 50% chance that the child is only carrying the gene, and a 25% chance that the child In Canada, in 2008, cystic fibrosis affects one in every 3,600 newborns. Geneticists estimate that one in every 25 people has the number of Canadians with the gene responsible for cystic fibrosis.
In Quebec, this proportion is 1 in 20. Generally, the parents of a child with cystic fibrosis do not have the disease. Often they do not know they carry the gene, and do not understand how they were able to pass it on to their baby. In August 1989, Canadian researchers discovered the normal gene that, when mutant, causes cystic fibrosis. If the child inherits a copy of this defective gene from each parent, some cells in the body will produce a protein that will not work normally.
Cystic fibrosis is not contagious and is not transmitted from one child to another.
Researchers are currently working on defining the exact role of this protein. What is sure until now is that it impedes the movement of salts and fluids through the membranes of the affected cells. This action produces the characteristic symptoms of cystic fibrosis, the accumulation of thick and dry mucus in the lungs, and obstruction of the pancreatic ducts. Cystic fibrosis is a hereditary disease and does not depend on the environment.
The birth order of the child, the age of the parents or the mother's diet during pregnancy do not determine whether or not the newborn will have cystic fibrosis.