How do people get cystic fibrosis?
Cystic fibrosis is a genetic disease. That means people inherit it from their parents through genes (or DNA), which also determine a lot of other characteristics including height, hair color and eye color. Genes, found in the nucleus of all the body's cells, control cell function by serving as the blueprint for the production of proteins.
The defective gene that is responsible for causing cystic fibrosis is on chromosome 7. To have cystic fibrosis, a person must inherit two copies of the defective CF gene—one copy from each parent. If both parents are carriers of the CF gene (i.e., they each have one copy of the defective gene), their child will have a 25% chance of inheriting both defective copies and having cystic fibrosis, a 50% chance of inheriting one defective copy and being a carrier, and a 25% chance of not having CF or carrying the gene.
Who gets cystic fibrosis?
Approximately 30,000 people in the United States have cystic fibrosis. An additional ten million more—or about one in every 31 Americans—are carriers of the defective CF gene, but do not have the disease. The disease is most common in Caucasians, but it can affect all races.
The severity of cystic fibrosis symptoms is different from person to person. The most common symptoms are:
- Very salty-tasting skin
- Persistent coughing, at times with phlegm
- Frequent lung infections, like pneumonia or bronchitis
- Wheezing or shortness of breath
- Poor growth/weight gain in spite of a good appetite
- Frequent greasy, bulky stools or diificulty in bowel movements
- Small, fleshy growths in the nose called nasal polyps
Sometimes people are told that they have asthma or chronic bronchitis when they really have cystic fibrosis. New research shows that the severity of CF symptoms is partly based on the types of CF gene mutations (defects). Scientists have found more than 1,500 different mutations of the CF gene.
How is CF diagnosed?
Most people are diagnosed with CF at birth or before the age of 2. A doctor who sees the symptoms will order either a sweat test or a genetic test to confirm the diagnosis.
A sweat test is the most common test used to diagnose cystic fibrosis. A small electrode is placed on the skin (usually on the arm) to stimulate the sweat glands. Sweat is then collected and the amount of chloride, a component of salt in the sweat, is measured. A high level of chloride—a score of more than 60 mmol/L (a measure of concentration)—means that the person has cystic fibrosis. Scores between 40 mmol/L and 60 mmol/L are considered to be on the borderline and need to be looked at on a case-by-case basis. Scores of less than 40 mmol/L are considered negative for CF. The best place to receive a reliable sweat test is at a Cystic Fibrosis Foundation-accredited care center .
In a genetic test , a blood sample or cells from the inside of the cheek is taken and sent to a laboratory to see if any of the various mutations of the CF gene are found. A genetic test is often used if the results from a sweat test are unclear.
How does CF affect the lungs?
Scientists have many different ideas about what goes wrong in the lungs of a person with cystic fibrosis, but it all begins with defective CF genes. Normally, the healthy CF gene makes a protein—known as CFTR (Cystic Fibrosis conductance Transmembrane Regulator)—that is found in the cells that line various organs, like the lungs and the pancreas. This protein controls the movement of electrically charged particles, like chloride and sodium (components of salt) in and out of these cells. When the protein is defective, as in cystic fibrosis, the salt balance in the body is disturbed. Because there is too little salt and water on the outside of the cells, the thin layer of mucus that helps keep the lungs free of germs becomes very thick and difficult to move. And because it is so hard to cough out, this mucus will clog the airways and lead to infections that damage lungs.
Is cystic fibrosis fatal?
Currently, there is no cure for cystic fibrosis. However, specialized medical care, aggressive drug treatments , and therapies , along with proper CF nutrition , can lengthen and improve the quality of life for those with CF.
The best way for people with cystic fibrosis to fight their disease is to work with their medical caregivers at a CF Foundation-accredited care center . The care center partners with people who have CF to help keep them in the best health possible.
What is a typical day for someone with CF?
Because the severity of CF differs widely from person to person, and CF lung infections flare up from time to time, there may not be a “typical” day. However, each day most people with CF:
- Take pancreatic enzyme supplement capsules with every meal and most snacks (even babies who are breastfeeding may need to take enzymes).
- Take multi-vitamins.
- Do some form of airway clearance at least once and sometimes up to four or more times a day.
- Take aerosolized medicines. These are liquid medications that are made into a mist or aerosol and then inhaled through a nebulizer.
What is the life expectancy for people who have CF?
There is no way to accurately predict how long people with cystic fibrosis will live, as many different factors may affect a person's health. Severity of disease and time of diagnosis are two such factors. Many people have a mild case of CF, while others can have moderate or severe cases. In addition, some adults with cystic fibrosis have only recently begun to use new treatments, while an infant diagnosed at birth will have the advantages of starting specialized treatments that were not available even a decade ago.
What treatments or therapies are available?
The best treatments and therapies for cystic fibrosis varies from person to person. CF medical caregivers at a CF Foundation-accredited care center will work closely with the person with CF to create an individualized plan as to what drugs and therapies are needed.
Since cystic fibrosis affects the lungs of most patients, a large part of the medical treatment is to clear mucus from the airways by using different airway clearance techniques. These techniques use vibrations to help loosen the mucus in the lungs so it can be coughed out. For more information, read Airway Clearance Techniques .
There are several medications that treat lung infections and can help people with cystic fibrosis breathe better. They are:
- Mucus-thinners – Medicine that thins mucus, making it easier to cough out.
- Antibiotics – Drugs that can kill or slow the growth of germs called bacteria.
- Anti-inflammatories – Drugs, like ibuprofen, help to reduce inflammation or swelling of the body tissues. People with CF have inflammation in their lungs. This is one cause of the lung damage.
- Bronchodilators – Medicine that opens the airways for easier breathing.
Does a lung transplant cure CF?
No. A lung transplant will not cure CF because the defective genes that cause the disease are in all of the cells in the body, not just in the lungs. At this time, scientists are not sure how to “fix” genes permanently (see gene therapy) . While a transplant does give a person with CF a new set of lungs, the rest of the cells in the body still have CF and may already be damaged by the disease. Further, organ rejection drugs can cause other health problems.
What about gene therapy? Is it a treatment for people with CF?
When scientists found the most common gene that causes CF in 1989, there was much excitement about the possibility of developing gene therapy. Gene therapy is the process by which healthy genes are delivered into cells and tissues of the body using such “vehicles” as a specially engineered virus. Researchers need to add enough healthy genes to override the effects of the defective ones. If it is successfully done, gene therapy has the potential of curing cystic fibrosis as it addresses the root cause of the disease (the faulty CF gene) and not merely the symptoms.
Scientists are currently exploring the use of gene therapy for many diseases but have had little success. That is because it has been very hard to find a safe and reliable way to deliver healthy genes into the cells and tissues of the body. For this reason, we cannot predict when and if gene therapy will become available as a treatment. Gene therapy, like any other medical research, must be safe and effective before it can be used as a treatment. Research is ongoing in both the clinic and the laboratory.