Test For Cystic Fibrosis
Cystic Fibrosis (also known as CF, mucovoidosis, or mucoviscidosis) is a hereditary disease affecting the exocrine (mucus) glands of the lungs, liver, pancreas, and intestines, causing progressive disability due to multisystem failure.
Thick mucus in the lungs production results in frequent lung infections. Diminished secretion of pancreatic enzymes is the main cause of poor growth, greasy stools, and deficiency in fat-soluble vitamins. Males can be infertile due to the condition congenital bilateral absence of the vas deferens. Often, symptoms of CF appear in infancy and childhood. Meconium ileus is a typical finding in newborn babies with CF.
Individuals with CF can be diagnosed prior to birth by genetic testing. Newborn screening tests are increasingly common and effective (although false positives may occur, and children need to be brought in for a sweat test to distinguish disease vs carrier status). The diagnosis of CF may be confirmed if high levels of salt are found during a sweat test, although some false positives may occur.
There is no known cure for CF, and most individuals with cystic fibrosis die young: many in their 20s and 30s from lung failure. The predicted median age of survival for a person with CF is 37 years. However, with the continuous introduction of many new treatments, the life expectancy of a person with CF is increasing to ages as high as 40 or 50. Lung transplantation is often necessary as CF worsens.
Cystic fibrosis is one of the most common life-shortening genetic diseases. In the United States, 1 in 4,000 children is born with CF. It is most common among western European populations; one in twenty-two people of Mediterranean descent is a carrier of one gene for CF, making it the most common genetic disease in these populations. In 1997, about 1 in 3,300 caucasian children in the United States was born with cystic fibrosis. In contrast, only 1 in 15,000 African American children suffered from cystic fibrosis, and in Asian Americans the rate was even lower at 1 in 32,000.
CF is caused by a mutation in the gene, cystic fibrosis transmembrane conductance regulator (CFTR). The product of this gene is a chloride ion channel important in creating sweat, digestive juices, and mucus. Although most people without CF have two working copies (alleles) of the CFTR gene, only one is needed to prevent cystic fibrosis. CF develops when neither allele can produce a functional CFTR protein. Therefore, CF is considered an autosomal recessive disease.
Symptomatic diseases
Lung and sinus disease
Lung disease results from clogging the airways due to mucosa buildup and resulting inflammation. Inflammation and infection cause injury to the lungs and structural changes that lead to a variety of symptoms. In the early stages, incessant coughing, copious phlegm production, and decreased ability to exercise are common. Many of these symptoms occur when bacteria that normally inhabit the thick mucus grow out of control and cause pneumonia. In later stages of CF, changes in the architecture of the lung further exacerbate chronic difficulties in breathing.
Other symptoms include coughing up blood (hemoptysis), changes in the major airways in the lungs (bronchiectasis), high blood pressure in the lung (pulmonary hypertension), heart failure, difficulties getting enough oxygen to the body (hypoxia), and respiratory failure requiring support with breathing masks such as bilevel positive airway pressure machines or ventilators. In addition to typical bacterial infections, people with CF more commonly develop other types of lung disease. Among these is allergic bronchopulmonary aspergillosis, in which the body's response to the common fungus Aspergillus fumigatus causes worsening of breathing problems. Another is infection with Mycobacterium avium complex (MAC), a group of bacteria related to tuberculosis, which can cause further lung damage and does not respond to common antibiotics.
Mucus in the paranasal sinuses is equally thick and may also cause blockage of the sinus passages, leading to infection. This may cause facial pain, fever, nasal drainage, and headaches. Individuals with CF may develop overgrowth of the nasal tissue (nasal polyps) due to inflammation from chronic sinus infections. These polyps can block the nasal passages and increase breathing difficulties.
Gastrointestinal, liver and pancreatic disease
Prior to prenatal and newborn screening, cystic fibrosis was often diagnosed when a newborn infant failed to pass feces (meconium). Meconium may completely block the intestines and cause serious illness. This condition, called meconium ileus, occurs in 10% of newborns with CF. In addition, protrusion of internal rectal membranes (rectal prolapse) is more common in CF because of increased fecal volume, malnutrition, and increased intra–abdominal pressure due to coughing.
The thick mucus seen in the lungs has a counterpart in thickened secretions from the pancreas, an organ responsible for providing digestive juices which help break down food. These secretions block the movement of the digestive enzymes into the duodenum and result in irreversible damage to the pancreas, often with painful inflammation (pancreatitis). The lack of digestive enzymes leads to difficulty absorbing nutrients with their subsequent excretion in the faeces, a disorder known as malabsorption. Malabsorption leads to malnutrition and poor growth and development because of calorie loss. Individuals with CF also have difficulties absorbing the fat-soluble vitamins A, D, E, and K. In addition to the pancreas problems, people with cystic fibrosis experience more heartburn, intestinal blockage by intussusception, and constipation. Older individuals with CF may also develop distal intestinal obstruction syndrome when thickened feces cause intestinal blockage.
Thickened secretions also may cause liver problems in patients with CF. Bile secreted by the liver to aid in digestion may block the bile ducts, leading to liver damage. Over time, this can lead to cirrhosis, in which the liver fails to rid the blood of toxins and does not make important proteins such as those responsible for blood clotting.
Endocrine disease and growth
The pancreas contains the islets of Langerhans, which are responsible for making insulin, a hormone that helps regulate blood glucose. Damage of the pancreas can lead to loss of the islet cells, leading to diabetes that is unique to those with the disease. Cystic Fibrosis Related Diabetes (CFRD), as it is known as, shares characteristics that can be found in Type 1 and Type 2 diabetics and is one of the principal non-pulmonary complications of CF. Vitamin D is involved in calcium and phosphorus regulation. Poor uptake of vitamin D from the diet because of malabsorption leads to the bone disease osteoporosis in which weakened bones are more susceptible to fractures. In addition, people with CF often develop clubbing of their fingers and toes due to the effects of chronic illness and low oxygen in their tissues.
Poor growth is a hallmark of CF. Children with CF typically do not gain weight or height at the same rate as their peers, and occasionally are not diagnosed until investigation is initiated for poor growth. The causes of growth failure are multi–factorial and include chronic lung infection, poor absorption of nutrients through the gastrointestinal tract, and increased metabolic demand due to chronic illness.
Infertility
Infertility affects both men and women. At least 97 percent of men with cystic fibrosis are infertile but are not sterile and can have children with assisted reproductive techniques. These men make normal sperm but are missing the tube (vas deferens), which connects the testes to the ejaculatory ducts of the penis. Many men found to have congenital absence of the vas deferens during evaluation for infertility have a mild, previously undiagnosed form of CF. Some women have fertility difficulties due to thickened cervical mucus or malnutrition. In severe cases, malnutrition disrupts ovulation and causes amenorrhea.
Diagnosis and monitoring
Cystic fibrosis may be diagnosed by many different categories of testing including those such as, newborn screening, sweat testing, or genetic testing. As of 2006 in the United States, 10 percent of cases are diagnosed shortly after birth as part of newborn screening programs. The newborn screen initially measures for raised blood concentration of immunoreactive trypsinogen. Infants with an abnormal newborn screen need a sweat test in order to confirm the CF diagnosis. Trypsinogen levels can be increased in individuals who have a single mutated copy of the CFTR gene (carriers) or, in rare instances, even in individuals with two normal copies of the CFTR gene. Due to these false positives, CF screening in newborns is somewhat controversial. Most states and countries do not screen for CF routinely at birth. Therefore, most individuals are diagnosed after symptoms prompt an evaluation f
Test For Cystic Fibrosis
This lost salt forms the basis for the sweat test. [2] How this malfunction of cells in cystic fibrosis causes the clinical manifestations of CF is not well understood.
Cystic fibrosis - Wikipedia, the free encyclopedia
However, most women's test results are normal. Cystic fibrosis cannot be treated before birth. The purpose of having this information about your developing baby is so you can ...
Cystic Fibrosis Carrier Testing: The Decision is Yours
Cystic Fibrosis Foundation - 2009, Sweat Test ... Overview. The sweat test has been the “gold standard” for diagnosing cystic fibrosis (CF) for more than 40 years.
Cystic Fibrosis Foundation - Sweat Test
FDA Approves First DNA-based Test to Detect Cystic Fibrosis. Rockville, MD: National Press Office; May 16, 2005. Press Release P05-23. Update Date: 5/1/2007
MedlinePlus Medical Encyclopedia: Cystic fibrosis
Cystic Fibrosis Foundation - 2009, Testing for Cystic Fibrosis
Cystic Fibrosis Foundation - Testing for Cystic Fibrosis
Overview of cystic fibrosis, one of the most common recessive genetic diseases in the US
Cystic Fibrosis
Lear about the sweat chloride test used to diagnose cystic fibrosis, a genetic disease common in Caucasians.
Sweat Chloride Test for Cystic Fibrosis Information on MedicineNet.com
The cystic fibrosis sweat test is the least invasive form of testing for Cystic Fibrosis|cystic fibrosis.
Cystic Fibrosis Sweat Test - OrganizedWisdom Health
Carrier testing is a special test involving the cystic fibrosis gene. Genes are found in the body's cells, and each gene contains a molecular code that determines how cells function.
What is cystic fibrosis ?
Because cystic fibrosis can affect several organs, other tests may be helpful.
