Cystic Fibrosis

Cystic fibrosis (abbreviated CF), also called mucoviscidosis, is an autosomal recessive hereditary disease that affects the lungs, sweat glands and the digestive system. The disease can be diagnosed by a high salt concentration in a baby's sweat. The symptoms usually develop during early childhood. Both lungs and pancreas produce abnormally viscous mucus. The mucus in the lungs can become a growth medium for bacteria, resulting in chronic respiratory infections and eventual permanent damage to the lung tissue. As their lung function gets worse, they develop pulmonary hypertension and eventually cor pulmonale. Death usually occurs from severe infection or heart failure.

In addition to frequent pulmonary infections, persons with CF also have problems absorbing fat soluble vitamins. They also are lacking in pancreatic enzymes. They therefore need to be supplemented with vitamins A, D, E, and K as well as pancrease enzyme.

In its most common form, a single amino acid mutation leads to the production of an abnormal protein (CFTR = cystic fibrosis transmembrane conductance regulator) important in transporting chloride ions across epithelial cells found in the lung and intestinal tract. Since water follows ions by osmosis, this results in water depleted and viscous mucus.

Cystic fibrosis was first described as a disease in the late 1930s. It is the most common genetic disease among people with European ancestry. Approximately one in every 25 people carries one normal and one CF gene. Since cystic fibrosis is recessive, both copies of the gene have to be CF genes to cause the symptoms that occur in about 1 in every 2500 children. The high incidence of this lethal gene can be explained by the fact that CF carriers, who don't show any symptoms, enjoy some protection against cholera, since the extreme water loss in the intestines is prevented. People from areas where cholera is not a problem show a much lower incidence of CF.

By advanced medical procedures, the life expectancy of a newborn with cystic fibrosis increased from 4 years (in the 1960s) to 32 years today. These procedures include the intake of digestion enzymes, nutritional supplements, percussion and postural drainage of the lungs, improved antibiotics and inhalation of aerosols containing medication. A few attempts of gene therapy were initially successful, but failed to produce acceptable long-term results. Some sufferers of cystic fibrosis go on to have a heart-lung transplant.

External links:

• UK Cystic Fibrosis Trust
• GeneTests GeneReview on Cystic Fibrosis