What is Cystic Fibrosis?

Cystic Fibrosis is an inherited condition that affects many functions of the body: breathing, digestion and reproduction. This lifelong condition usually becomes more severe with age and can affect both males and females. See Diagram

In CF, the glands that produce mucus, saliva and intestinal fluids do not work properly. People with Cystic Fibrosis have secretions that are thick and sticky rather than thin and watery. This type of mucus in the lungs interferes with the removal of dust and germs which leads to breathing problems and infections. Along the digestive tract, secretions may clog the tubes leading from the pancreas to the intestine where essential enzymes work to breakdown food elements. If the enzymes cannot reach the food, then it cannot be broken down fully and essential nutrients are lost before they can be used by the body. Secretions can also coat other parts of the digestive tract and these may block the absorption of nutrients and occasionally cause serious intestinal blockage. Both of these processes can result in slow or poor growth and low weight gain. Other systems can be affected by similar secretion blockages.

The symptoms and severity of Cystic Fibrosis differ from person to person. The majority of patients have both respiratory and digestive problems, while some people may only have respiratory symptoms.

Most people with CF are diagnosed in childhood. Some, with mild or unrecognised symptoms may not be diagnosed until adolescence or adulthood. Common symptoms include chronic cough, wheezing, sinus infections, excessive mucus production, recurrent pneumonia, poor growth, and skin that is salty to the taste.

The diagnosis of CF is usually made when a "sweat test" is performed on the surface of the skin and high levels of salt (i.e., sodium and chloride ions) are detected. Genetic testing can also be used to diagnose CF.

In 1989 scientists announced that they had isolated the gene responsible for Cystic Fibrosis. A copy of this gene must be contributed by each parent in order for a child to be affected. The gene carries the code which directs cells to produce a protein that regulates the movement of chloride back and forth across cell membranes through what are called 'chloride channels'. This protein is called the cystic fibrosis transmembrane conductance regulator (CFTR).

Chloride is one of the most essential elements to the body and it is distributed throughout every cell. [Chloride is a companion ion to sodium, which, when combined forms sodium chloride, or common table salt.] Because the chloride ion concentration cannot be regulated by passing through the chloride channels, a number of problems arise. The main organs affected by this chloride ion transport problem are the lungs, liver, pancreas, small intestine and reproductive system.

It is ironic that about 70 per cent of cystic fibrosis cases are caused by the deletion on only three nucleotides (DNA building blocks) from the gene. And yet this deletion results in a defect to the chloride channels which leads to widespread organ malfunction.

To date, there is no cure for Cystic Fibrosis. Better treatment strategies help to improve the length and quality of life of people with CF by controlling their symptoms. Hospitalisation may be required for the treatment of lung infections. Physiotherapy plays a major role by helping to remove mucus from the lungs, and this greatly enhances breathing. Pancreatic enzymes are taken with meals to help digestion. To maintain weight, frequent, high-calorie meals and snacks are recommended. These strategies concentrate on the two functional systems where the greatest numbers of problems arise: respiratory and gastrointestinal systems.

Hospitals which specialise in CF care have multi-disciplinary teams composed of professionals who have expertise in CF care. These teams are often comprised of many types of doctors (paediatricians, respiratory physicians, gastroenterologists, and endocrinologists), CF specialist nurses, physiotherapists, dieticians, pharmacists, social workers, and psychologists. The concentration of resources into expert regional centres results in better long term care for CF patients.

Much of the treatment for cystic fibrosis can also take place in the home. This involves regular physiotherapy to clear the lungs, and oral antibiotics to treat mild flare-ups. In addition, some antibiotics may now be inhaled using special breathing apparatus. This treatment should be done frequently and may also be done at home.

In recent years, it has been possible to deliver intravenous antibiotic treatment at home, with close supervision by the specialist hospital unit.

General practitioners play a major role in that they can provide back-up and vigilance, plus they can liaise with the hospital and other services on the patients' behalf.

References:

Cystic Fibrosis Gene Testing in Ireland. Prof Andrew Green, Director, National Centre for Medical Genetics, Our Lady’s Children’s Hospital, Crumlin, Dublin 12, Ireland.