There are more than 1,000 mutations of the gene for cystic fibrosis. The disease affects nearly all the body's glands that secrete fluids into a duct. It also affects many organs.
Some symptoms of cystic fibrosis include:
- Mucus blocks the small airways of the lungs, which become inflamed and sometimes infected.
- Frequent sinus infections because the sinuses fill with thickened mucus
- The lymph nodes swell
- Thick secretions can block the bile ducts in the liver. This can lead to swelling and tenderness (inflammation) of the liver and eventual scarring (cirrhosis). Cirrhosis can put pressures on the veins of the liver, causing the veins at the lower end of the esophagus to get large and fragile. These veins can rupture and bleed.
- The gall bladder can become blocked
- Thick secretions can block the pancreas entirely preventing digestive enzymes from reaching the intestines to help break down and absorb food. This can cause nutritional deficiencies as fats, proteins and vitamins are poorly absorbed. Children with cystic fibrosis grow more slowly than other children.
- Thick secretions that require surgery to remove in some newborns can block the small intestine. Between 15 and 20% of newborns with cystic fibrosis have meconium ileus, a serious blockage of the small intestine. They are also more prone to twisting of the intestine on itself or an incompletely developed intestine.
Other possible symptoms include:
- A big appetite that does not lead to weight gain
- Delayed puberty
- Excessive sweating in hot weather or during a fever (This sweating puts the patient at greater risk of dehydration.)
- Frequent lung or respiratory infections and a greater risk of developing a collapsed lung
- Greasy, bulky stools
- Loss of physical endurance
- Persistent coughing that sometimes produces phlegm
- Skin that tastes very salty or carries salt crystals
- Wheezing or shortness of breath
One of the first signs of cystic fibrosis in a baby is slowness to gain weight in the weeks after birth. Because of a lack of pancreatic enzymes for proper digestion, the baby does not get enough nutrition to thrive. The baby may also have a distended stomach and small muscles.
Nearly half the children with cystic fibrosis are diagnosed when they are taken to the doctor because of frequent coughing, wheezing and respiratory tract infections. The coughing can be accompanied by gagging, vomiting and disturbed sleep.
Over time, the chest becomes barrel-shaped. The lack of oxygen causes the fingers to be bigger at the tips. The area under the fingernails looks bluish.
Because of the digestive problems that cystic fibrosis creates, a variety of nutritional complications can develop. These include night blindness, rickets, anemia (a lack of iron in the blood) and bleeding disorders. About 15% of adults with cystic fibrosis develop diabetes that requires treatment with insulin.
The condition also affects the reproductive system. More than 95% of men with cystic fibrosis are sterile. Although many women with cystic fibrosis are able to conceive children, the impact of the disease on their lungs and health may make carrying a child to term quite difficult.
Causes and Risk Factors
A defective gene causes cystic fibrosis. The gene controls the production of a protein that controls how salt is carried across the membranes that separate cells. People with one copy of the defective gene carry it but have no symptoms, which is the case for more than 10 million Americans. However, those who receive a copy of the defective gene from both parents will develop cystic fibrosis.
Cystic fibrosis affects Caucasians five times more often than it does African Americans. It is rare in Asian-American children. It affects boys and girls equally.