Cystic Fibrosis

Cystic Fibrosis (CF) is an inheritable autosomal recessive disorder that affects the exocrine gland function, making it one of the most common life-shortening diseases. In white people it is the most common lethal inherited disease. Most carriers are asymptomatic. The most frequent mutation that originates this condition is to be found on chromosome 7, on the gene that codes for the protein cystic fibrosis transmembrane conductance regulator (CFTR).

People with cystic fibrosis typically have an abnormally thick mucus layer that builds up in the lungs and digestive tract. It is one of the most common chronic lung diseases in children and young adults. Approximately 80% of deaths result from loss of lung function linked to inflammation due to chronic bacterial infection (principally Pseudomonas aeruginosa). Additional frequent problems concern chronic respiratory infections, pancreatic enzyme insufficiency and associated complications in untreated patients.

Mutations
Approximately 70 percent of the mutations in cystic fibrosis patients correspond to a specific deletion of three base pairs, which results in the loss of a phenylalanine residue at amino acid position 508 of the putative product of the cystic fibrosis gene. This mutation (ΔF508) affects the maturation and function of a protein that functions as a chloride channel and is regulated by cyclic adenosine monophosphate (cAMP). The cAMP-regulated transport of chloride, across epithelial cell membranes on mucosal surfaces, is deficient. As a result, the chloride secretion decreases and the reabsorption of sodium and water by the cell increases.

Many other mutation causing cystic fibrosis have been discovered (over one thousand). This is why the direct diagnosis of the disease may be less efficent if the mutation is unknown.

Symptoms
Symptoms in newborns may include delayed growth, failure to gain weight normally in childhood, no bowel movements in first 24 to 48 hours of life and salty-tasting skin. Symptoms related to the respiartory system can include increased mucus in sinuses or lungs, recurrent episodes of pneumonia and sinus pain or pressure caused by infection or polyps.

Frequency and Mortality
About 30,000 people in the United States have cystic fibrosis and around 1,000 new cases of cystic fibrosis are diagnosed each year. 

Currently, the median age of survival is 36.9 years, being the median age of survival significantly higher in males than in females.