Association Fibrose Kystique

What is cystic fibrosis?

A FATAL HEREDITARY DISEASE

Genetic risk factors

Cystic fibrosis (CF) is the fatal genetic disease most common among young Canadians; their number is estimated at 3,500. There would be 1,200 cases in Quebec.

In 2008, in Canada, cystic fibrosis affects on average one in every 3,600 newborns and one person in 25 is a carrier of the defective version of the gene associated with this disease. In Quebec, this proportion is one in 20. In most cases, people do not know they are carriers as they do not have cystic fibrosis and show none of its symptoms.

Because carriers have only one copy of the gene responsible for cystic fibrosis, they will never develop the disease. However, when two carriers of the defective gene have a child, there is a:

• 25% risk that the child will be born with cystic fibrosis;

• 50% risk that the newborn will not suffer from CF, but will be a carrier of the gene;

• 25% risk that the newborn will neither suffer, nor be a carrier of CF.

These probabilities are the same for each pregnancy produced by the union of the two carriers.

Vital organs that degenerate

CF affects several vital organs, but attacks mostly the lungs and the digestive system.

In healthy persons, the mucous in the body is fluid and helps keep lungs and airways clear, promoting the elimination of microbes and dust particles.

In persons suffering from CF, this mucous is thick and sticky; it obstructs bronchioles, making breathing more difficult. Air is therefore trapped in some of the bronchioles and the lungs are blocked by the mucous. Bacteria accumulate and proliferate in the bronchioles thus obstructed, resulting in severe and recurring infections, which in turn cause lung tissue to deteriorate. Pulmonary problems are the main cause of death of persons suffering from cystic fibrosis.

Similarly, mucous blocks fine pancreatic ducts; the pancreas is an organ located near the intestines, under the stomach. It secretes digestive enzymes which normally flow into the small intestine; these enzymes ensure digestion. When the orifices of the pancreas are blocked by the mucous, enzymes can no longer reach their destination and food leaves the intestine only partially digested, thus losing part of its nutritional value.

Symptoms

• Difficulty breathing.

• Persistent cough with expectoration of thick mucous.

• Extreme appetite associated with weight loss.

• Intestinal problems.

• Salty-tasting skin.

• Long lasting and recurrent pneumonia.

• Failure to thrive.

Cystic fibrosis was first described at the end of the 30s. At that time, it was recognized only after the death of the child, mostly from malnutrition or pneumonia.

In time, medical knowledge of cystic fibrosis has clearly improved. Yet it is still sometimes mistaken for other common diseases such as asthma, chronic bronchitis, recurrent pneumonia and celiac disease.

Screening

In Quebec, there is no systematic screening program for cystic fibrosis in newborns. In spring 2007, the Canadian Cystic Fibrosis Foundation (CCFF) tabled an expert report to the ministère de la Santé et des Services sociaux du Québec which recommended it. CCFF would like Quebec to follow the lead of Alberta, Ontario, Saskatchewan and British Columbia and adopt an early screening program using IRT and DNA tests.