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Cystic Fibrosis: Overview and Risk Factors

Cystic fibrosis (CF) is a systemic disease of the exocrine glands characterized by a progressive obstructive lung disease (bronchiectasis) and exocrine pancreatic insufficiency. The sweat glands, vas deferens, and other organs are also affected to varying degrees.

CF is the most common inherited genetic disorder in North America. In the United States, approximately 30,000 individuals have the condition and about 12 million people are carriers. Cystic fibrosis is also the most common cause of pancreatic insufficiency in children. Because normal absorption and digestion of nutrients, especially fat, are altered by pancreatic insufficiency, failure to thrive, malnutrition, and growth retardation are common clinical features in the absence of treatment. The median age of survival is approximately 35 years.

CF is caused by mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which controls the concentration of sodium and chloride across certain epithelial cell membranes. Its disruption causes abnormal sodium resorption and chloride secretion. This in turn produces thick mucus, which renders lungs susceptible to bacterial infections. Destruction of the pancreas is typically present at birth, resulting in the absence of digestive enzymes released into the digestive tract. Over 1,000 mutations of this gene have been identified; the most common is the DF508 mutation.

Risk Factors

Genetics. CF is an autosomal recessive condition. If both parents are carriers, a child has a 25% chance of having the disease and a 50% chance of also being a carrier. One in 25 Caucasians is a carrier. A family history of cystic fibrosis and unexplained infant death are also risk factors.

Race. The prevalence of CF is approximately 1 in 2,500 for Caucasians, 1 in 15,000 for African Americans, and 1 in 30,000 for Asian Americans.

 

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Cystic Fibrosis: Diagnosis >>