What is cystic fibrosis?

Cystic fibrosis is an inherited condition that is caused by mutation of a gene found at the chromosome 7. It is more common among people of Northern European ancestry. The disease causes sticky mucus to build up in the lungs, digestive system and other organs. This causes lung infections, problems with digesting food and a number of related conditions such as diabetes, liver problems, osteoporosis and infertility in males.

Disease genetics

The gene associated with cystic fibrosis was found in 1989. The commonest gene mutation is called f508del or ΔF508. This mutation is found in 70% of people in North America, whereas in Greece it is estimated to exist in 50-55% of the population. Almost 2000 mutations causing cystic fibrosis have been found.

The gene that is related to cystic fibrosis codes for the production of the protein Cystic Fibrosis Transmembrane Regulator (CFTR). Dysfunction of this gene results in problematic production or function of a protein that regulates the transfer of chloride ion between cells. As a result, sticky mucous is produced that blocks the ducts of glands in various organs.

Inheritance

Cystic fibrosis is inherited in an autosomal recessive manner. People who suffer from the disease have mutations in both copies of the gene for the CFTR. Those with a single working copy are carriers and otherwise healthy.

  • If both parents are carriers, there is a 25% chance that the child suffers from cystic fibrosis, 50% that the child is a healthy carrier and 25% that the child is healthy and has no mutation.
  • If one parent has cystic fibrosis and the other is a carrier, then the child has 50% chance of having the disease and 50% chance of being a healthy carrier.
  • If only one parent is a carrier and the other does not have the mutation, then there is no chance of having a child that suffers from the disease but there is 50% chance that the child is a healthy carrier.
  • Finally, if both parents have the disease, then all children are going to have cystic fibrosis.

Frequency

It is estimated that 50-60 children per year are born with cystic fibrosis in Greece, whereas the carriers represent 4-5% of the general population (almost 500.000 Greeks). The most common mutation found in the Greek population is the f508del or Δf508.

Symptoms

The main characteristic of the disease is the production of sticky mucus that blocks the glands of various organs, mainly the lungs and pancreas. This results in severe pancreatic failure from an early age and serious chronic lung infections that gradually destroy the lungs and lead to respiratory failure.

Disease prognosis

  • There is no radical treatment for Cystic Fibrosis. The management of the disease depends on the symptoms and their severity and differs for each patient.
  • With appropriate treatment 8 out of 10 children with Cystic Fibrosis could leave up to the age of 50 or more.
  • Most people live a normal life provided that they take treatment. However, there might be exacerbation of their symptoms. Most patients die from complications of the disease mainly from respiratory or cardiac failure.

Diagnosis

  1. Genetic diagnosis
    The genetic test for Cystic Fibrosis checks for the presence of Δf508 mutation or other mutations for the disease.
  2. Sweat test
    Cystic fibrosis patients have abnormally high levels of salt in their sweat. The test can be performed even from the first few days of life is there are symptoms suggestive of the disease. The sweat test measures the amount of chloride (a component of salt) in the sweat. There are no needles involved in this test.
  3. Prenatal test

The prenatal test for Cystic Fibrosis is performed with chorionic villus sampling (CVS) or amniocentesis if both parents are carriers of a mutation, if the couple already has an affected child or is there are findings at the fetal ultrasound such as echogenic bowel.

For more information you could visit the following website: www.cysticfibrosis.gr