Cystic fibrosis

DEFINITION

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Cystic fibrosis is a life-threatening disorder that causes severe damage to the lungs and digestive system.

An inherited condition, cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. These secreted fluids are normally thin and slippery. But in cystic fibrosis, a defective gene causes the secretions to become thick and sticky. Instead of acting as a lubricant, the secretions plug up tubes, ducts and passageways, especially in the lungs and pancreas.

Cystic fibrosis is most common in white people of Northern European ancestry, but also occurs in Hispanics, African-Americans and some Native Americans. It is rare in people of Asian and Middle Eastern origin.

Although cystic fibrosis requires daily care, most people with the condition are able to attend school and work, and have a better quality of life than in previous decades. Recent improvements in screening and treatments mean most people with cystic fibrosis now live into their 20s and 30s, and some are living into their 40s and 50s.

CAUSES

In cystic fibrosis, a defect (mutation) in a gene changes a protein that regulates the movement of salt in and out of cells. The result is thick, sticky mucus in the respiratory, digestive and reproductive systems, as well as increased salt in sweat. Many different defects can occur in the gene. The type of gene mutation is associated with the severity of the condition.

The affected gene, which is inherited from a child’s parents, is a recessive gene. Children need to inherit one copy of the gene from each parent in order to have the disease. If children inherit only one copy, they won’t develop cystic fibrosis, but will be carriers and possibly pass the gene to their own children.

SYMPTOMS

Cystic fibrosis signs and symptoms vary, depending on the severity of the disease. Even in the same person, symptoms may worsen or improve as time passes. In some children, symptoms begin during infancy. Other people may not experience symptoms until adolescence or adulthood.

Screening of newborns for cystic fibrosis is now performed in all 50 states. As a result, the condition is diagnosed within the first month of life, before symptoms develop. For people born before newborn screening was performed, it’s important to be aware of the signs and symptoms of cystic fibrosis.

People with cystic fibrosis tend to have a higher than normal level of salt in their sweat. Parents often can taste the salt when they kiss their children. Most of the other signs and symptoms of cystic fibrosis affect the respiratory system or the digestive system.

Respiratory signs and symptoms

The thick and sticky mucus associated with cystic fibrosis clogs the tubes that carry air in and out of your lungs. This can cause:

• A persistent cough that produces thick spit (sputum) and mucus
• Wheezing
• Breathlessness
• A decreased ability to exercise
• Repeated lung infections
• Inflamed nasal passages or a stuffy nose

Digestive signs and symptoms

The thick mucus can also block tubes that carry digestive enzymes from your pancreas to your small intestine. Without these digestive enzymes, your intestines can’t fully absorb the nutrients in the food you eat. The result is often:

• Foul-smelling, greasy stools
• Poor weight gain and growth
• Intestinal blockage, particularly in newborns (meconium ileus)
• Severe constipation

Frequent straining while passing stool can cause part of the rectum — the end of the large intestine — to protrude outside the anus (rectal prolapse). When this occurs in children, it may be a sign of cystic fibrosis. Parents should consult a physician knowledgeable about cystic fibrosis. Rectal prolapse in children may require surgery.

When to see a doctor

Talk to your doctor if your child:

• Isn’t growing properly
• Has a persistent cough that produces mucus
• Has repeated lung or sinus infections
• Has frequent fatty, bad-smelling stools
• Has rectal prolapse

Seek immediate medical care if your child has difficulty breathing.