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Cystic fibrosis (CF) is an inherited disease of mucus and sweat glands. It affects mostly lungs, pancreas, liver, intestines, sinuses, and sex organs.
Normally, mucus is a slippery, watery substance. It keeps the linings of certain organs moist and prevents them from drying out or getting infected. But in CF, an abnormal gene causes mucus to become thick and sticky. The mucus builds up in lungs and blocks the airways. This makes it easy for bacteria to grow and leads to repeated serious lung infections. Over time, these infections can cause serious damage to lungs.
The thick, sticky mucus can also block tubes, or ducts, in pancreas. As a result, digestive enzymes that are produced by pancreas cannot reach small intestine. These enzymes help break down the food. Without them, intestines cannot absorb fats and proteins fully, resulting in chronic malnutrition.
CF also causes your sweat to become very salty. As a result, your body loses large amounts of salt when you sweat. This can upset the balance of minerals in your blood and cause a number of health problems. Examples include dehydration (a condition in which your body doesn't have enough fluids), increased heart rate, tiredness, weakness, decreased blood pressure, heat stroke, and, rarely, death.
The symptoms of CF vary from person to person and over time. Sometimes you will have few symptoms. Other times, your symptoms may become more severe.
One of the first signs of cystic fibrosis (CF) that parents may notice is that their baby's skin tastes salty when kissed or the baby doesn't pass stool when first born.
Most of the other signs and symptoms of CF develop later. They are related to how CF affects the respiratory, digestive, or reproductive systems of the body.
Respiratory System Signs and Symptoms
People who have CF have thick, sticky mucus that builds up in their airways. This buildup of mucus makes it easier for bacteria to grow and cause infections. Infections can block the airways and cause frequent coughing that brings up thick sputum (spit) or mucus that's sometimes bloody.
People who have CF tend to have lung infections caused by unusual germs that don't respond to standard antibiotics. For example, lung infections due to bacteria called mucoid Pseudomonas are much more common in people who have CF. An infection caused by this bacteria may be a sign of CF.
People who have CF have frequent bouts of sinusitis, an infection of the air-filled spaces behind your eyes, nose, and forehead. Frequent bouts of bronchitis and pneumonia also occur. These infections can cause long-term lung damage.
As CF gets worse, you may develop more serious complications, such as pneumothorax, or collapsed lung; or bronchiectasis.
Some people who have CF also develop nasal polyps (growths in the nose) that may require surgery.
Digestive System Signs and Symptoms
Mucus that blocks tubes, or ducts, in your pancreas and prevents enzymes from reaching your intestines causes most digestive system signs and symptoms.
Without these enzymes, your intestines can't fully absorb fats and proteins. This can cause ongoing diarrhea or bulky, foul-smelling, greasy stools. Intestinal blockage also may occur, especially in newborns. Too much gas or severe constipation in the intestines may cause stomach pain and discomfort.
A hallmark of CF in children is poor weight gain and growth. These children are unable to get enough nutrients from their food due to the lack of enzymes to help absorb fats and proteins.
As CF gets worse, other complications may occur, such as:
Reproductive System Signs and Symptoms
Men who have CF are infertile because they're born without a vas deferens. This is the tube that delivers sperm from the testicle to the penis.
A woman who has CF may have a hard time getting pregnant because of mucus blocking her cervix or other CF complications.
Other Signs, Symptoms, and Complications
Other signs and symptoms of CF are related to an upset of the balance of minerals in your blood.
CF causes your sweat to become very salty. As a result, your body loses large amounts of salt when you sweat. This can cause dehydration (a condition in which your body doesn't have enough fluids), increased heart rate, tiredness, weakness, decreased blood pressure, heat stroke, and, rarely, death.
CF also can cause clubbing and low bone density. Clubbing is the widening and rounding of the tips of your fingers and toes. It develops late in CF because your lungs aren't moving enough oxygen into your bloodstream.
Low bone density also tends to occur late in CF. It can lead to a bone-thinning disorder called osteoporosis.
Doctors diagnose cystic fibrosis (CF) based on the results from various tests.
Most States screen newborns for CF using a genetic test or a blood test. The genetic test shows whether a newborn has faulty CFTR genes. The blood test shows whether a newborn's pancreas is working.
If a genetic test or blood test suggests CF, a doctor will confirm a diagnosis using a sweat test. This test is the most useful test for diagnosing CF. It measures the amount of salt in sweat.
For this test, doctors trigger sweating on a small patch of skin on an arm or leg. They rub the skin with a sweat-producing chemical and then use an electrode to provide a mild electrical current. This may cause a tingling or warm feeling.
Sweat is collected on a pad or paper and then analyzed. The sweat test usually is done twice. High salt levels confirm a diagnosis of CF.
If you or your child has CF, your doctor may recommend other tests, such as:
If you're pregnant, prenatal genetic tests can find out whether your fetus has CF. These tests include amniocentesis and chorionic villus sampling (CVS).
In amniocentesis, your doctor inserts a hollow needle through your abdominal wall into your uterus. He or she removes a small amount of fluid from the sac around the baby. The fluid is tested to see whether both of the baby's CFTR genes are normal.
In CVS, your doctor threads a thin tube through the vagina and cervix to the placenta. The doctor removes a tissue sample from the placenta using gentle suction. The sample is tested to see whether the baby has CF.
Cystic Fibrosis Carrier Testing
People who have one normal CFTR gene and one faulty CFTR gene are CF carriers. CF carriers usually have no symptoms of CF and live normal lives. However, carriers can pass faulty CFTR genes on to their children.
If you have a family history of CF or a partner who has CF (or a family history of it) and you're planning a pregnancy, you may want to find out whether you're a CF carrier.
A genetics counselor can test a blood or saliva sample to see whether you have a faulty CF gene. This type of testing can detect faulty CF genes in 9 out of 10 cases.
A defect in the CFTR gene causes cystic fibrosis (CF). This gene makes a protein that controls the movement of salt and water in and out of your body's cells. In people who have CF, the gene makes a protein that doesn't work right. This causes thick, sticky mucus and very salty sweat.
Research suggests that the CFTR protein also affects the body in other ways. This may help explain other symptoms and complications of CF.
More than a thousand known defects can affect the CFTR gene. What type of defect you or your child has may influence how severe CF is. Other genes also may play a role in how severe the disease is.
How Is Cystic Fibrosis Inherited?
Every person inherits two CFTR genes—one from each parent. Children who inherit a faulty CFTR gene from each parent will have CF.
Children who inherit a faulty CFTR gene from one parent and a normal CFTR gene from the other parent will be "CF carriers." CF carriers usually have no symptoms of CF and live normal lives. However, carriers can pass the faulty CFTR gene on to their children.
The following image shows how two parents who are both CF carriers can pass the faulty CFTR gene to their children.