Cystic fibrosis (also known as CF or mucoviscidosis) is an autosomal recessive genetic disorder affecting most critically the lungs, and also the pancreas, liver, and intestine. It is characterized by abnormal transport of chloride and sodium across an epithelium, leading to thick, viscous secretions.
An inherited condition, cystic fibrosis affects the cells that produce mucus, sweat and digestive juices. Normally, these secretions are 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 pancreas and lungs.
Approximately 30,000 children and adults in the United States have cystic fibrosis. An additional ten million more—or about one in every 31 Americans—are carriers of the defective CF gene, but do not have the disease. CF is most common in Caucasians, but it can affect all races.
A sweat test is the most common test used to diagnose cystic fibrosis and is considered the diagnostic "gold standard." A small electrode is placed on the skin (usually on the arm) to stimulate the sweat glands. Sweat is then collected and the amount of chloride, a component of salt in the sweat, is measured. A high level of chloride means that the person has cystic fibrosis.
Although there is no cure for CF, treatments have improved greatly in recent years. Until the 1980s, most deaths from CF occurred in children and teenagers. Today, with improved treatments, some people who have CF are living into their forties, fifties, or older.
In the pancreas, the mucus blockage can interfere with normal digestive processes and increase the risk of infection. Babies and children who have cystic fibrosis may not be able to absorb nutrients from food and may have below-normal growth and development. Weight loss and difficulty gaining or maintaining weight are common problems for people of all ages who have cystic fibrosis.
Early symptoms of cystic fibrosis include abnormally salty sweat or skin and a failure to thrive, which includes a poor appetite, lack of energy, and weight loss during infancy. Some babies who have cystic fibrosis are born with a blocked small intestine. Later symptoms include coughing up mucus and a lack of energy. Adults who have cystic fibrosis may have fertility problems.
Early treatment for CF can improve your quality of life and increase your lifespan. Treatments may include nutritional and respiratory therapies, medicines, exercise, and other treatments.
The affected gene, which is inherited from a child's parents, is a recessive gene. With recessive genes, children need to inherit two copies of the gene, one 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.
Almost 1,400 different mutations of the CF gene can lead to cystic fibrosis (some mutations cause milder symptoms than others). About 70% of people with CF have the disease because they inherited the mutant gene Delta F508 from both of their parents. This can be detected by genetic testing, which can be done in kids both before and after birth and in adults thinking about starting or enlarging their families.
As chronic infections reduce lung function, the ability to breathe often decreases. A person with CF may eventually begin to feel short of breath, even when resting. Despite aggressive medical therapy, lung disease develops in nearly all patients with CF and is a common cause of disability and shortened life span.