Cystic Fibrosis Term Paper
- Length: 10 pages
- Subject: Genetics
- Type: Term Paper
- Paper: #70538479
Excerpt from Term Paper :
cystic fibrosis. There are eleven references used for this paper.
There are a number of fatal diseases which a person can be born with in the world today. One of the most debilitating is Cystic Fibrosis. It is important to examine its history, symptoms, diagnostic procedures, treatments and prognosis in order to gain a better understanding of this disease.
Cystic fibrosis is a "recessive disorder common among Caucasians. Although the disease was known in the 1930's, it was only in the late 1980's that the molecular mechanisms about its development were established (Tsui)." In the United States, "one in 2500 people in the general population is born with cystic fibrosis (http://www.phd.msu.edu/DNA/cf_fam.pdf)."
Cystic fibrosis is sometimes referred to as '65 roses.' This nickname "came from a little boy who overheard his mom talking about the condition on the phone. He thought that each time his mom said 'cystic fibrosis,' she was talking about 65 roses (http://kidshealth.org/teen/diseases_conditions/digestive/cystic_fibrosis.html)."
Occurrence of Cystic Fibrosis
In the United States, in "Caucasians with cystic fibrosis:
50% have two copies of ?F508 (the most common mutation)
40% have one copy of the deletion and one other mutation.
10% do not have the ?F508 deletion.
In cystic fibrosis carriers of other ethnic backgrounds, the ?F508 deletion is present in:
45% of Italians
30% of African-Americans
30% of Ashkenazi Jews (http://www.phd.msu.edu/DNA/cf_fam.pdf)."
Cystic fibrosis presents with a number of symptoms. These symptoms can "include:
No meconium stool in first 24 hr. Of life
Stools, pale or clay colored and foul smelling
Stools - floating
Skin may taste salty (infants)
Persistent respiratory infections such as pneumonia
Coughing or wheezing
Clubbing of the fingers or toes
Causes of Symptoms
Meconium is a "black, tarry stool-like substance that comes out soon after birth, within the first few days of life (http://www.cysticfibrosis.com/info/index.html)." When a baby is unable to expel this meconium due to a blockage in the bowel, it is referred to as a Meconium Ileus. In a baby with cystic fibrosis, the meconium may not be expelled, "due to the intestinal secretions causing a blockage. Meconium Ileus occurs in approximately 15% of the cases, is a very serious condition, and requires surgery to eliminate the problem within a few hours, or the baby will not survive (http://www.cysticfibrosis.com/info/index.html)."
Patients with cystic fibrosis may not be able to "digest their food correctly due to pancreatic insufficiency, resulting in the production of greasy, bulky, foul-smelling stools (http://www.cysticfibrosis.com/info/index.html)."
Cystic fibrosis may cause a condition known as 'Failure to Thrive', during which a child is unable to "gain weight or grow in height normally (http://www.cysticfibrosis.com/info/index.html)."
Patients with cystic fibrosis may experience reoccurring lung and sinus infections, and have a large amount of secretions in the respiratory system. The formation of secretions occurs when the patient is "unable to clear them because they are thick, and often infected (http://www.cysticfibrosis.com/info/index.html)." These chronic respiratory infections may cause the patient to cough frequently, and patients who also suffer from asthma may experience wheezing.
Sufferers may have nasal congestion from "chronic sinusitis and/or polyps, with nasal polyps requiring surgery.
The patient may be infected with Pseudomonas aeruginosa or Burkholderia cepacia. Bad, or foul-smelling breath may be noticed, that no amount of teeth brushing or breath fresheners can get rid of, usually due to respiratory (lung and/or sinus) infections, such as Pseudomonas aeruginosa, but may also be due to improper digestion (http://www.cysticfibrosis.com/info/index.html)."
The basic symptom is "salty sweat. The patient may also dehydrate easily, find it difficult to gain weight due to malabsorption and fighting infection, experience stomach aches, and have vitamin or mineral deficiency due to malabsorption, especially Vitamin K (http://www.cysticfibrosis.com/info/index.html)."
In the past 10 years there have been a number of advances in the diagnosis of cystic fibrosis due to research in molecular biology and genetics.
Early diagnosis "of the disease not only can lead to the most appropriate medical management of the patient but also allows for genetic counseling and pulmonary surveillance (Andolsek)."
The "traditional diagnostic criteria for cystic fibrosis include the following: persistently elevated concentrations of electrolytes in sweat along with characteristic clinical findings (such as typical gastrointestinal or pulmonary disease and perhaps obstructive azoospermia) or a family history (Andolsek)."
Sweat testing is the main diagnostic tool used to determine classic cystic fibrosis, however additional tests must be utilized to determine atypical forms of cystic fibrosis.
Complications in Diagnosis
There may be complications in diagnosing patients with an atypical form of the disease, including "patients who present with cystic fibrosis late in childhood or in adulthood. These patients may lack characteristic gastrointestinal and pulmonary symptoms, and may have less widely known complications such as pancreatitis, congenital absence of the vas deferens and nasal polyps (Andolsek)."
Additional Diagnostic Tests
Health care practitioners may administer a number of additional tests in order to determine cystic fibrosis. These tests can include "sweat testing, genotyping, semen analysis, sinus radiographs, tests of exocrine pancreatic function, nasal potential-difference measurements, and bronchoalveolar lavage. The correlation of the genotype with phenotype, as well as rational use of clinical signs and laboratory tests is used to both diagnose and rule out cystic fibrosis (Andolsek)."
The "encoded gene product known as the cystic fibrosis transmembrane conductance regulator (CFTR) has been identified through gene mapping and cloning techniques. Studies have shown however, that CFTR mutations are more profound than cystic fibrosis alone by inducing pancreatic disorder (Tsui)."
In conditions of single gene disorders such as cystic fibrosis, "the chromosomes, or karyotype, are expected to be normal, 46, XX or 46, XY and therefore, chromosome studies are not recommended for these patients (http://med.usd.edu/som/genetics/curriculum/1DCHROM2.htm)."
Understanding Cystic Fibrosis
While most people are able to breath without difficulty, and rarely even think about the act, those suffering from cystic fibrosis find it an almost daily struggle. "Thick, gooey mucus clogs the lungs of most people with the disease and serves as a breeding ground for bacteria. Chronic infections lead to respiratory failure - typically caused by the usually harmless bacterium called Pseudomonas aeruginosa - which kills most people with cystic fibrosis while they are in their 20s or early 30s. This suggests that either the lungs of cystic fibrosis patients are particularly hospitable to bacteria or normal defenses against infection are somehow weakened (Damaris)."
There are currently more than 30,000 cystic fibrosis patients in the United States, and more than "12 years after researchers identified the mutated gene responsible for the disease, scientists are still struggling to determine how its function relates to the pathology of cystic fibrosis (Damaris)."
Family History and Carriers
Cystic fibrosis is "a hereditary disease. To inherit cystic fibrosis, two abnormal genes, one from each parent are passed on. Genetic testing can show whether a person carries the common gene changes known to cause cystic fibrosis by analyzing DNA from a small amount of cells or blood (http://www.cysticfibrosis.com/info/index.html)." The easiest methods of collecting cells for genetic testing are using a cheekbrush kit to obtain cells from the mouth or drawing a blood sample. The DNA "from these cells can be isolated and used in the laboratory to test for the presence of cystic fibrosis gene mutations (http://www.cysticfibrosis.com/info/index.html)."
While it is important for anyone who has a family history of cystic fibrosis to be tested as a carrier, "80% of children with cystic fibrosis are born to parents with no prior history of the disease. Testing can detect about 80-90% of the carriers of cystic fibrosis. While testing may not be able to provide complete information on carrier status for all individuals, if a person is found to have a mutation then he or she is a carrier, and if there is not identifiable mutation, the chance of being a carrier is much less, but not zero (http://www.phd.msu.edu/DNA/cf_fam.pdf)."
In patients who have a "family history of cystic fibrosis, it is best to test the person with cystic fibrosis first and determine which mutations her or she has. Relatives can then be tested to see if they carry the same mutation. If a close relative does not have these same mutations, the chance for them to be a carrier is quite small (http://www.phd.msu.edu/DNA/cf_fam.pdf)."
Changes in the Body
The body of a patient who has cystic fibrosis undergoes a number of changes. Each gene has its own specific DNA code, which defines the gene's role. DNA is composed of "four building blocks called bases. These bases are joined in a specific order for each gene, and when a change occurs in the arrangement of the bases, it can cause the gene not to work properly. A structural gene change which can cause a disease or a birth defect is called a mutation (http://www.phd.msu.edu/DNA/cf_fam.pdf)." As previously noted, a person with cystic fibrosis inherits the mutated cystic fibrosis gene from each parent. This mutated gene is large, and currently there are "over 700 cystic fibrosis mutations know, most of which are very rare. The most common mutation is referred to as the ?F508 deletion (http://www.phd.msu.edu/DNA/cf_fam.pdf)." The form of genetic testing used in determining this…