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.
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.
Symptoms of cystic fibrosis
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 lung function deteriorates, CF patients develop pulmonary hypertension and eventually cor pulmonale.
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. Cystic Fibrosis also causes a defect in the vas deferens causing sterility in approximately 98% of males with the disease.
Death usually occurs from severe infection or heart failure.
Treatment of cystic fibrosis
By advanced medical procedures, the median 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.
Recent medical research is beginning to show that an imbalance of essential fatty acids may play a role in Cystic Fibrosis. Tissue samples from both mice, and more recently humans, with CF show an excess of arachidonic acid (AA) and a deficiency of docosahexaenoic acid (DHA). Research has also indicated that healthy individuals with one copy of the CF gene and one copy of the normal gene have fatty acid levels in between those of CF patients and people with no CFTR gene mutations. Further research is needed to show how this is linked to the CFTR gene defect and what implications this may have on treatment of Cystic Fibrosis. Some sufferers of cystic fibrosis go on to have a lung transplant.