Preston Hall
4/15/2013
Biology 1010
Cystic Fibrosis (CF)
Cystic fibrosis is a disease passed down through families that causes thick, sticky mucus to build
up in the lungs, digestive tract, and other areas of the body. It is one of the most common chronic lung
diseases in children and young adults. It is a life-threatening disorder.
Cystic fibrosis (CF) is caused by a defective gene which causes the body to produce abnormally
thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and in
the pancreas, the organ that helps to break down and absorb food. This collection of sticky mucus
results in life-threatening lung infections and serious digestion problems.
The disease may also affect the sweat glands and a man's reproductive system. Millions of
Americans carry the defective CF gene, but do not have any symptoms. That's because a person with CF
must inherit two defective CF genes -- one from each parent. An estimated 1 in 29 Caucasian Americans
have the CF gene. The disease is the most common, deadly, inherited disorder affecting Caucasians in
the United States. It's more common among those of Northern or Central European descent. Most
children with CF are diagnosed by age 2. A small number, however, are not diagnosed until age 18 or
older. These patients usually have a milder form of the disease.
CF is caused by a mutation in the gene cystic fibrosis transmembrane conductance regulator
(CFTR). The most common mutation, ΔF508, is a deletion of three nucleotides that results in a loss of the
amino acid phenylalanine (F) at the 508th position on the protein. This mutation accounts for two-thirds
(66–70%) of CF cases worldwide and 90% of cases in the United States; however, there are over 1500
other mutations that can produce CF. Although most people have two working copies (alleles) of the
CFTR gene, only one is needed to prevent cystic fibrosis. CF develops when neither allele can produce a
functional CFTR protein. Thus, CF is considered an autosomal recessive disease.
In addition, there is increasing evidence that genetic modifiers besides CFTR modulate the
frequency and severity of the disease. One example is mannan-binding lectin, which is involved in innate
immunity by facilitating phagocytosis of microorganisms. Polymorphisms in one or both mannan-binding
lectin alleles that result in lower circulating levels of the protein are associated with a threefold higher
risk of end-stage lung disease, as well as an increased burden of chronic bacterial infections.
Symptoms
Symptoms in newborns may include:
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Delayed Growth
Failure to gain weight normally during childhood
No bowel movements in first 24 to 48 hours of life
Salty-tasting skin
Symptoms related to bowel function may include:
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Belly pain from severe constipation
Increased gas, bloating, or a belly that appears swollen (distended)
Nausea and loss of appetite
Stools that are pale or clay colored, foul smelling, have mucus, or that float
Weight loss
Symptoms related to the lungs and sinuses may include:
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Coughing or increased mucus in the sinuses or lungs
Fatigue
Nasal congestion caused by nasal polyps
Recurrent episodes of pneumonia. Symptoms in someone with cystic fibrosis include:
o Fever
o Increased coughing
o Increased shortness of breath
o Loss of appetite
o More sputum
Sinus pain or pressure caused by infection or polyps
Symptoms that may be noticed later in life:
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Infertility (in men)
Repeated inflammation of the pancreas (pancreatitis)
Respiratory symptoms
Signs and tests
A blood test is available to help detect CF. The test looks for variations in a gene known to cause the
disease. Other tests use to diagnose CF include:
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Immunoreactive trypsinogen (IRT) test is a standard newborn screening test for CF. A high level
of IRT suggests possible CF and requires further testing.
Sweat chloride test is the standard diagnostic test for CF. A high salt level in the patient's sweat
is a sign of the disease.
Other tests that identify problems that can be related to cystic fibrosis include:
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Chest x-ray or CT scan
Fecal fat test
Lung function tests
Measurement of pancreatic function
Secretin stimulation test
Trypsin and chymotrypsin in stool
Upper GI and small bowel series
Treatment
An early diagnosis of CF and a comprehensive treatment plan can improve both survival and quality of
life. Follow-up and monitoring are very important. If possible, patients should be cared for at cystic
fibrosis specialty clinics, which can be found in many communities. When children reach adulthood, they
should transfer to a cystic fibrosis specialty center for adults.
Treatment for lung problems includes:
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Antibiotics to prevent and treat lung and sinus infections. They may be taken by mouth, or given
in the veins or by breathing treatments. People with cystic fibrosis may take antibiotics only
when needed, or all the time. Doses are usually higher than normal.
Inhaled medicines to help open the airways
DNAse enzyme therapy to thin mucus and make it easier to cough up
High concentration of salt solutions (hypertonic saline)
Flu vaccine and pneumococcal polysaccharide vaccine (PPV) yearly (ask your health care
provider)
Lung transplant is an option in some cases
Oxygen therapy may be needed as lung disease gets worse
Lung problems are also treated with aerobic exercise or other therapies to thin the mucous and make it
easier to cough up out of the lungs. These include a Percussion Vest, manual chest percussion, A-capella,
or TheraPEP device.
Treatment for bowel and nutritional problems
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A special diet high in protein and calories for older children and adults
Pancreatic enzymes to help absorb fats and protein
Vitamin supplements, especially vitamins A, D, E, and K
Your doctor can suggest other treatments if you have very hard stools
Care and monitoring at home should include:
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Avoiding smoke, dust, dirt, fumes, household chemicals, fireplace smoke, and mold or mildew
Clearing or bringing up mucus or secretions from the airways. This must be done one to four
times each day. Patients, families, and caregivers must learn about doing chest percussion and
postural drainage to help keep the airways clear
Drinking plenty of fluids. This is particularly true for infants, children, in hot weather, when there
is diarrhea or loose stools, or during extra physical activity
Exercising two or three times each week. Swimming, jogging, and cycling are good options.
Expectations (prognosis)
Most children with cystic fibrosis are fairly healthy until they reach adulthood. They are able to
participate in most activities and should be able to attend school. Many young adults with cystic fibrosis
finish college or find employment.
Lung disease eventually worsens to the point where the person is disabled. Today, the average life span
for people with CF who live to adulthood is approximately 37 years, a dramatic increase over the last
three decades.
Death is usually caused by lung complications.
Complications
The most common complication is chronic respiratory infection.
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Bowel problems, such as gallstones, intestinal obstruction, and rectal prolapse
Coughing up blood
Chronic respiratory failure
Diabetes
Infertility
Liver disease or liver failure, pancreatitis, biliary cirrhosis
Malnutrition
Nasal polyps and sinusitis
Osteoporosis and arthritis
Pneumonia, recurrent
Pneumothorax
Right-sided heart failure
Prevention
There is no way to prevent cystic fibrosis. Screening those with a family history of the disease may
detect the cystic fibrosis gene in 60 - 90% of carriers, depending on the test used.