Cystic Fibrosis (CF) is an
inherited disease that causes problems with a group of glands, called the
exocrine glands. Exocrine glands normally produce thin, slippery
secretions. In CF, the secretions are thick and sticky. CF mainly
causes problems in the respiratory and digestive systems, but other systems are
affected as well.
Normally, glands in the airway walls of
your lungs produce thin, slippery mucous for a specific purpose - to help trap
dust and bacteria that we inhale on a daily basis. This thin mucous is then
moved up towards the trachea (windpipe) by tiny beating hairs called cilia where
it can be coughed up or swallowed. In CF lungs this mucous is thick and sticky,
making it harder for the cilia to do their job of sweeping the mucous away from
your lungs. This thick mucous then builds up in the airways and plugs them up.
This can cause air trapping, airway closure and infection.
Thick mucous may also block the
ducts of the pancreas. The pancreas is a gland located below and behind the
stomach. It is one of the important organs of the digestive tract.
It supplies enzymes needed to digest food. When openings from the
pancreas are blocked, enzymes cannot reach the small intestine. As a result,
food is only partially digested and the nutritional value reduced. In fact, 85%
of people with CF don't secrete enough enzymes to completely
digest food. This leads to weight loss and poor growth.
Thick sticky mucous can also block the ducts of the liver called bile ducts. Bile ducts are small tubes that carry bile form the liver. Bile is used for fat digestion.
Parts of the reproduction system, sinuses and sweat glands are also affected by CF. Cystic Fibrosis is a multiple organ disease.
For people with CF, life includes a daily routine of therapy and visits to the CF clinic. Otherwise, most CF individuals lead normal lives in terms of education, physical activity and social relationships.
At the moment there is no cure for CF, but there is hope. Thanks to advancements in research and clinical care, increasing numbers of children are surviving into adulthood. Nearly 60% of all individuals with CF in Canada are adults.
Since 1989 when Canadian researchers discovered the gene
responsible for CF, global research to find a cure for the disease has brought
us closer and closer to a solution.
Over the last decade, major improvements and
discoveries in therapy have greatly enhanced the quality of life—and life
expectancy—for people with CF and there is a good reason to feel optimistic
about the future.
Genetics of CF
DNA
CF is one of the most common hereditary diseases, meaning you are born with it. One in every 3,600 children born in Canada has cystic fibrosis.
The CF gene is recessive which means a person must inherit two defective genes in order to have CF. Therefore, if you have CF you must have received one CF gene from each of your parents. It is estimated that one in every 25 Canadians is a carrier of the CF gene. A person who is a carrier has only one copy of the CF gene and therefore does not have CF. But this person can pass on the gene to his or her children.
When two people who are carriers of the CF gene have a child, there is a 25% chance the child will
be born with CF, a 50% chance the child will not have CF but will be a carrier
and a 25% chance that the child will not have CF and will not be a carrier. This
risk is the same for each pregnancy.
How is a CF Diagnosis made?
If there is asuspicion of CF, a "sweat test" is often the first test done. This testanalyzes the salt content of sweat. A high salt content points to adiagnosis of CF. A person may or may not have other symptoms.
A genetic analysis from a blood sample is also used to confirm the diagnosis of CF. There are over 1,800 mutations in the gene responsible for CF, but people are usually tested for 30 of the ones that are most common. Genetic tests can be done to make a prenatal diagnosis as well.
Signs and Symptoms of CF
Because CF affects more than one
body system, a person with CF may experience a variety of symptoms. The
following are some of the most common:
a constant cough which produces thick mucous
weight loss or failure to gain weight
skin which tastes salty
excessive stooling pattern and
large, bulky, foul smelling stools
frequent chest infections which may include pneumonia
wheezing and shortness of breath
clubbing
infertility or decreased fertility
Reference
David M. Orenstein. Cystic Fibrosis: A Guide for Patients and Family. 2nd ed. Philadelphia: Lippincott-Raven;1997.
Cystic Fibrosis Canada 2221 Yonge Street, Suite 601 Toronto, Ontario M4S 2B4 Telephone: (416)485-9149 or 1 800 378-2233 www.cysticfibrosis.ca
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