Cystic fibrosis, or CF, is a fatal inherited illness caused by a mutation in a gene that leads to the buildup of thick, sticky mucus in the lungs and pancreas. The mucus makes breathing challenging and prevents correct nutrition by blocking the flow of digestive enzymes from the pancreas. Most patients eventually die in late adolescence or their early adult years from damage to the lungs caused by the buildup of scar tissue (fibrosis).
CF is a disease that affects numerous organ systems in the body. The defective gene involved in cystic fibrosis results in lower levels of chloride, a chemical compound that is important in the production of sweat, digestive juices, and mucus of regular consistency. Chloride regulates the flow of water in and out of cells, which is needed to produce mucus that is thin sufficient to act as a lubricant and sweat that contains regular amounts of salt.
When there's not sufficient chloride, the mucus that the tissues produce is thicker and stickier; it interferes with the proper functioning of the lungs, pancreas, sweat glands, and digestive tract. The thick mucus in the lungs provides a breeding ground for bacteria and fungi, which trigger inflammation and gradual destruction of lung tissue.
In the digestive system, the mucus blocks the ducts that convey digestive enzymes from the pancreas, a large gland located just below the stomach. Without these enzymes, the patient's body can't absorb nutrients from food as it passes via the digestive tract, a condition recognized as malabsorption. The thick mucus might also cause irreversible damage to the pancreas itself and trigger inflammation of the liver as well. In men, it might block the tubes that carry sperm from the testicles, thus leading to infertility.
Cystic fibrosis is primarily a disease of people of northern European ancestry; in reality it's the most typical fatal inherited illness among Caucasians in the United States, affecting one child in every 3,200. CF affects one in every 9,200 Hispanic kids, one in every 15-17,000 African American kids, and one in every 31,000 Asian American kids. As of 2008, there had been about 30,000 people with CF in the United States and about 70,000 in the world. Males and females are equally likely to be born with CF; however, females are more severely affected and tend to die at younger ages.
Cystic fibrosis is caused by a mutation in the CFTR gene located on chromosome 7. The gene itself was first identified in 1989. A child should inherit the defective gene from both parents in order to develop CF. If either parent has a regular CFTR gene, the child may be a carrier for the illness but will not have any symptoms of cystic fibrosis. You will find over 900 various recognized mutations of the CFTR gene.
You will find an estimated 10 million carriers of the defective gene in the United States, or almost one in every thirty-one people. If two carriers marry, they've a 25 percent chance of having a child with cystic fibrosis, along with a 50 percent chance of having a child who will be a carrier of the defective CFTR gene.
Some mutations of the CFTR gene trigger more severe symptoms than other people or may affect different body systems differently. In addition, the symptoms of CF vary somewhat with age. In newborns, the intestines might be blocked by meconium (a blackish-green stool that most babies pass in the first couple of days after birth). These children might also have such symptoms as failure to grow; bulky and greasy stools; and frequent respiratory infections. In older children and young adults, symptoms of CF might include:
Some complications of CF that occur in some patients include liver damage; polyps (tissue growths) in the nose caused by recurrent sinus infections; frequent headaches; pain in the abdomen; and diabetes resulting from damage to the pancreas.
It is feasible to diagnose CF before birth around the eleventh week of pregnancy by testing a little piece of tissue from the placenta, the temporary organ that allows for exchange of nutrients and waste products between the mother and baby. After the sixteenth week of pregnancy, the fetus can be tested by amniocentesis, a procedure that involves withdrawing a small quantity of fluid from the sac that surrounds the baby before birth.
Many hospitals have newborn screening programs to evaluate babies for CF. Even though the screening techniques are not diagnostic tests in the strict sense, they can be used to rule out CF in most babies. In addition, by identifying babies who should be tested further for CF, screening allows treatment for the illness to be started as early as feasible.
The sweat test has been considered the best diagnostic test for cystic fibrosis for over forty years. It measures the amount of chloride in the person's sweat. To perform the test, the physician applies a chemical that causes sweating on a small area of the person's arm or leg. An electrode is attached to the treated area and a mild electrical current is utilized to stimulate sweating. The patient might feel a tingling or warm sensation.
After about five minutes, the sweat from the treated area is collected on a piece of filter paper and sent to a laboratory for analysis. One benefit of the sweat test is that the values aren't changed as a person grows older or affected by temporary illness. Another more recent test that could be utilized to diagnose CF is genetic testing of a sample of the patient's blood for mutations in the CFTR gene.
There is no cure for CF. Treatment is aimed at thinning the mucus secretions, keeping the patient's airways clear, preventing infections, and maintaining adequate nutrition. Medications used to treat CF include:
Adults as well as children with CF generally need to follow a special high-calorie high-fat diet to maintain great health. A professional dietitian can work with the patient to include foods that the patient enjoys eating as well as meeting the calorie and fat requirements. Patients with CF also need to clear the mucus from their lungs a minimum of twice a day.
This clearing can be done by having the patient lie with his or her head over the edge of a bed and thumping or clapping on the back and chest for twenty to thirty minutes to shake the mucus loose so that the patient can cough it up. As an alternative to having a physical therapist or trained family member thumping the patient's chest, the patient can wear a device known as a ThAIRapy Vest, which contains a compressor that vibrates the patient's chest wall at set times to loosen the mucus. The vest costs about $16,000. CF patients with advanced lung disease may benefit from lung transplantation.
Cystic fibrosis is a fatal illness. The average life expectancy of patients is 36.8 years, with males on average living longer than females. This is a dramatic increase over the 1950s, when few patients with CF lived long enough to begin elementary school. About 80 percent of patients live to be adults; a couple of patients live into their forties. Most patients die of end-stage lung disease. Most males with CF (97 percent) can't father kids. Women with CF are more likely to be fertile; however, they must watch their diet very carefully during pregnancy and might find that pregnancy worsens the symptoms of CF.
There's no way to stop cystic fibrosis other than genetic testing of possible parents. Genetic screening of family members of a cystic fibrosis patient might detect the CF gene in between 60 and 90 percent of carriers, depending on which test is used. You will find still a couple of rare mutations of the CFTR gene that can't be identified by present tests.
Cystic fibrosis was the first disease that researchers attempted to treat by using gene therapy, a technique for replacing defective genes in the body's tissues with normal genes. In 1993, scientists utilized a typical cold virus in an attempt to deliver a healthy CFTR gene to the cells in the patient's airways. Even though this first attempt was not effective, other methods of gene delivery are now being tested, including nose drops, fat capsules, and solutions delivered by nebulizers.
Another avenue of research involves mapping the genome of the bacterium that causes most of the lung infections in CF patients. By cracking the bacterium's genetic code, researchers are hoping to develop better drugs for treating the infections that it causes.
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