The Facts about Cystic Fibrosis

Cystic fibrosis (CF) is a chronic, progressive, and frequently fatal genetic disease of the mucus glands. Approximately 30,000 Americans, 3,000 Canadians and 20,000 Europeans have CF, according to the Cystic Fibrosis Foundation. The disease primarily affects the respiratory and digestive systems of children and young adults; although the sweat glands and reproductive system are also usually involved. People with CF typically have a lifespan of about 30 years.

Cystic fibrosis occurs mostly in Caucasians whose ancestors came from northern Europe, although it affects all races and ethnic groups. About 2,500 babies are born with CF each year in the United States, and approximately 1 in every 20 Americans carries an abnormal "CF gene" with no ill effects. For the most part these 12 million people are unaware that they are carriers.

What are the Signs and Symptoms of CF?
Babies born with CF genes usually have symptoms during their first year, but sometimes indicators of the disease do not show up until adolescence or even later. CF symptoms vary from child to child. Infants or young children should be tested for CF if they have persistent diarrhea; bulky, foul-smelling, greasy bowel movements; frequent wheezing or pneumonia; a chronic cough with thick mucus; salty-tasting skin or poor growth. CF should be suspected in babies born with an intestinal blockage called meconium ileus.

CF does not follow the same pattern in all patients, but the basic problem is the same – an abnormality in the glands that produce or secrete sweat and mucus. Sweat cools the body. Mucus lubricates the respiratory, digestive and reproductive systems, and prevents tissues from drying out to help protect against infections. People with CF lose excessive amounts of salt when they sweat. This can upset the balance of minerals in the blood, which may cause abnormal heart rhythms. Going into shock is also a risk.

The mucus of CF patients is very thick and builds up in the intestines and lungs. This results in malnutrition, poor growth, frequent respiratory infections, breathing difficulties, and eventually permanent lung damage CF can cause various other medical problems, including sinusitis, polyps inside the nose, rounding and enlargement of fingers and toes (called clubbing), pneumothorax (rupture of lung tissue), coughing up blood, heart enlargement, abdominal pain and discomfort and rectal prolapse. Liver disease, diabetes, inflammation of the pancreas, and gallstones also occur in some people with CF. Lung disease is the usual cause of death in most patients.

How is CF Diagnosed?
The most common test for CF is called the sweat test. It measures the amount of salt in the sweat. In this test, the skin – usually on the arm – is made to sweat by using a chemical called pilocarpine and applying a mild electric current. The skin is covered with gauze or paper to collect the sweat and wrapped in plastic. After 30 to 40 minutes the plastic is removed and the sweat is analyzed. Higher-than-normal amounts of sodium and chloride suggest that the person has cystic fibrosis.

A small percentage of people with CF have normal sweat chloride levels; they can only be diagnosed by chemical tests for the presence of the mutated gene. The sweat test might not work well in newborns because they do not produce enough sweat. In that case, another type of test can be used. Some of the other tests that can assist in the diagnosis of CF are chest x-rays, lung function tests, and sputum (phlegm) cultures. Stool examinations can help identify the digestive abnormalities that are typical of CF.

How Is CF Treated?
At present there is no treatment for the basic causes of CF, but several drugs are being investigated. In the meantime, the doctors can ease the symptoms of CF or slow the progress of the disease so the patient's quality of life is improved. People with CF receive antibiotic therapy combined with various treatments to clear the thick mucus from the lungs. For patients whose disease is very advanced, lung transplantation is sometimes an option.

Not too long ago CF was always fatal in childhood, but better treatment methods developed over the past 20 years have increased the average lifespan of CF patients to nearly 30 years. These treatment approaches include the following:

Management of Lung Problems
A major focus of CF treatment is the obstructed breathing that causes frequent lung infections. Physical therapy, exercise, and medications are used to reduce the mucus blockage of the lung's airways.

• Chest therapy consists of bronchial, or postural, drainage, which is done by placing the patient in a position that allows drainage of the mucus from the lungs. At the same time, the chest or back is clapped and vibrated to dislodge the mucus and help it move out of the airways. This process is repeated over different parts of the chest and back to loosen the mucus in different areas of each lung. This procedure has to be done for children by family members but older patients can learn to do it by themselves.
• Mechanical aids that help chest physical therapy are available commercially. Exercise also helps to loosen the mucus, stimulate coughing to clear the mucus, and improve the patient's overall physical condition.
• Medications used to help breathing are often aerosolized (misted) and can be inhaled. These medicines include bronchodilators to widen the breathing tubes, mucolytics to thin the mucus, and decongestants to reduce swelling in the breathing tube membranes. A recent advance, already approved by the Food and Drug Administration, is an inhaled aerosolized enzyme that thins the mucus by digesting the cellular material trapped in it.
• Antibiotics to fight lung infections also are used and may be taken orally or in aerosol form, or by injection into a vein.

Management of Digestive Problems
The digestive problems in CF are less serious and more easily managed than those in the lungs. A well-balanced, high-caloric diet, low in fat and high in protein, and pancreatic enzymes (which help digestion) are often prescribed. Supplements of vitamins A, D, E, and K are given to ensure good nutrition. Enemas and mucolytic agents are used to treat intestinal obstructions.

Genetics: A Cause and an Answer?
Genes are the basic units of heredity, and diseases such as CF that are caused by inherited genes are called genetic diseases. Genes cause cells to make particular proteins, most of which have important life-sustaining roles. A mutation can cause the body to make a defective protein or no protein at all. The result is a loss of some essential biological function and that leads to disease. Children may inherit altered genes from one or both parents. To have CF, a child must inherit two abnormal genes – one from each parent.

Gene therapy for CF is not yet possible but impressive progress is being made to treat the gene abnormality that causes CF. In the laboratory, scientists have been able to grow cells from CF patients and add the normal gene into these cells to correct some of the abnormal function.

Scientists are still looking for answers to many questions about gene therapy: How can we get the protective genes into the patient's lungs? What will be the long-term results of this treatment? Which abnormalities can be corrected? How long will the corrections last? And most importantly, can gene therapy cure or prevent lung disease in CF?

Can We Detect CF Before a Baby is Born?
We can find out whether a baby is likely to have CF by using prenatal genetic tests, but the tests cannot detect all of the CF gene mutations. Also, because the tests are very expensive and have certain risks to the mother, they are not used for all pregnant women. If there is another child with CF in the family, the expectant mother may ask for a prenatal test to see if the fetus has CF genes from both parents, is a carrier for one gene, or is free of the CF genes.

Two special prenatal tests can be done to test for CF genes. In amniocentesis, cells from the amniotic fluid surrounding the baby in the mother's womb are tested to see if the CF genes are present. In chorionic villus biopsy, cells from the tissue that will eventually form the placenta are tested for the CF genes.

Can We Prevent CF?
At this time, preventing CF is not possible. In babies with two abnormal CF genes, the disease is already present at birth in organs such as the pancreas and liver, but only develops in the lungs after the baby is born. Someday, we might be able to use gene therapy to prevent the lung disease from developing.

Since CF occurs only when both parents pass on a CF gene to a child, couples who are carriers might decide not to have children. However, as noted, current tests can detect only some of the more than 400 gene mutations and so the tests are only 80% to 85% accurate. Potential parents who carry the defective gene might also choose to have children. Progress in gene therapy and the realization that not all CF mutations are life-threatening should reassure couples.

How Can Patients, Families and Friends Cope with CF?
CF education helps patients and their families face the physical and emotional effects of the disease and encourages CF patients to lead active, fulfilling lives. Educational programs and materials suitable for patients of various ages and their parents are available from local CF centers and from local chapters of the CF Foundation.

Patients and their families and friends should know that:

• CF parents should not feel guilty or responsible for causing their child's disease; they could not have prevented it.
• Parents should treat their children with CF as normally as possible. They shouldn't be over-protective but should encourage them to be active and self-reliant.
• Family and friends should remember that CF is not contagious; nobody can get it from a patient.
• In families with CF, brothers, sisters and first cousins of the CF patient should be tested to see if they carry a defective gene, especially if they seem to have a chronic lung or digestive problem. Carriers of the abnormal gene should get genetic counseling.
• Individuals with CF have normal sexual development and can expect to have a normal sex life. However, most, but not all, men are infertile and cannot have children. Women with CF can have children, although they may be less fertile than women without CF.
• Patients and families should work closely with doctors and other medical specialists to develop self-management skills to improve their quality of life.

Above all, CF patients and their families should keep a positive attitude. Scientists continue to make significant advances in understanding the genetic and physiological disturbances in CF and in developing new treatment approaches such as gene therapy. The outlook is bright for further improvements in the care of CF patients and, perhaps, even the discovery of a cure.

Information provided by the National Institutes of Health/National Heart, Lung, and Blood Institute

For more information, see the HealthLink article Despite Breakthroughs, Cystic Fibrosis Answers Remain Elusive.

Each year, Medical College of Wisconsin physicians care for more than 180,000 patients, representing nearly 500,000 patient visits. Medical College physicians practice at Children's Hospital of Wisconsin, Froedtert Memorial Lutheran Hospital, the Milwaukee VA Medical Center, and many other hospitals and clinics in Milwaukee and southeastern Wisconsin.