What Causes CF?
CF is known as a recessive genetic disease which means that both parents must be carriers to have a child affected with CF.
A carrier does not have CF but does carry one CF gene. At the time of conception, a child inherits one set of genes from each parent, to have CF. If only one parent carries the CF gene, the children may be carriers but will not have CF.
When both parents are carriers, the odds are one-in-four that a child will have CF. There is a two-in-four chance a child will be a carrier, and a one-in-four chance a child will neither be a carrier nor have CF.
The defective gene responsible for CF is called CFTR, or Cystic Fibrosis Transmembrane Conductance Regulator. The most common defect is known as Δ F508 (delta 508). This defect is present in 96% of people with CF although many other mutations (well over 2000) have been identified.
Is There a Test to Detect CF Carriers?
Yes. Recent advances in gene research and the identification of the CF gene makes it possible to diagnose CF carriers. This involves a blood test which is sent to a specialized laboratory and analyzed for the 16 most common CF gene mutations.
Although there are well over 2000 mutations identified, the most common is Ð F508 which is found in approximately 96% of the "carrier" population. No other mutation is found in more than 4% of the 'carrier' population with most found in under 1% of the "carrier" population.
The test has a high degree of accuracy but is not 100% reliable because it may not pick up one of the rare mutations. It is best to check with your insurance company to determine the cost before proceeding.
It is also possible to detect the presence of CF in an unborn child, but this is generally reserved for cases in which both parents are known carriers. This, too, is done in conjunction with genetic counseling and physician recommendation. Newborn screening for CF is available in every state.
Symptoms of Cystic Fibrosis
What are Some Early Symptoms of CF?
CF has been called "the great masquerader" because its symptoms can be similar to other disorders such as asthma. The type and severity of symptoms often vary from person to person as does the age when they first appear.
Some early symptoms include:
- Excessively salty sweat
- Frequent or persistent cough
- Frequent or persistent respiratory infections
- Large, loose, clay-colored greasy stools
- Failure to thrive or delayed growth
- Large appetite or lack of appetite
About 10% of CF infants have what is called a meconiumileus or intestinal blockage at birth or shortly after birth. In young children, the presence of nasal polyps can also alert the physician that CF may be present.
People suspected of having CF are given a "sweat test" which measures the salt content of sweat and is almost 100% effective in diagnosing CF. The "sweat test" is a simple, painless, non-invasive procedure.
Why Do CF Symptoms Vary in Severity?
Just as every person is different, CF can affect each person differently. Some patients may have very few symptoms
and may not be diagnosed until their pre-teens or older. Others develop symptoms and complications early in life and experience progressive deterioration in health.
The reasons for the differences in severity are not always known but may be related to such things as the genetic defect itself, age at diagnosis, treatment compliance, inattention to nutritional needs as well as other genetic influences such as the person's immune response.
How is Cystic Fibrosis treated?
At present there is no cure for CF and treatment is aimed at treating the symptoms and preventing complications.
Current treatments include strict attention to growth and nutritional health. This is done by assessing the degree of malabsorption, attending to growth curves, using pancreatic enzymes to aid digestion, exercising as tolerated, and using nutritional supplements along with a well-rounded high calorie diet.
Respiratory therapy is of great importance to help clear secretions from the airways, prevent infection, and decrease lung damage. This includes manual CPT (chest percussion therapy) and mechanical devices such as nebulizers, percussors, flutter valves, and percussion vests to loosen secretions. In conjunction with this, medications (such as pulmozyme) to thin secretions and dilate the bronchi are used in an effort to loosen secretions and ease clearing.
CF researchers are investigating ways to replace the defective gene in the lungs and ultimately find a cure. The CF Foundation partnered with Vertex Pharmaceuticals in an effort to find medications that are aimed at replacing the defective gene. This effort has produced three medications that are somewhat effective in reducing the impact of the defective gene. They are kalydeco, orkambi, and most recently, trikafta. Although these medications have proven effective for many people with CF, researchers are hoping one or more of this trio will result in a long term beneficial treatment. Consequently, the pathway to a cure is very hopeful.
Currently the key to long-term survival in CF is the use of aggressive treatment of both nutritional deficiencies and bacterial infections with the possible addition of these new medications. This is an ongoing process even when things are going well. The emphasis is on maintaining optimal health and preventing complications.
Myths, Misconceptions, and General Information
CF is not contagious. The only way to "get" CF is to be born with it.
CF does not affect mental function or intelligence, and children with CF do not have to "live in a bubble" or be treated as invalids.
Although prone to lung infections, people with CF should be encouraged to live a so-called normal life attending school and socializing with friends, etc. General precautions should be taken to avoid prolonged exposure to people who have colds, the flu, or other infections.
Psycho-social development is another important aspect of living with CF. People with CF, especially children, should be encouraged to be as independent as possible, self-disciplined, and knowledgeable about the disease.