Cystic Fibrosis Research Paper

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Cystic Fibrosis (CF) is genetically inherited through a defective gene, which results in the body producing "abnormally thick and sticky fluid, called mucus. This mucus builds up in the breathing passages of the lungs and in the pancreas, the organ that helps to break down and absorb food." (PubMed Health, 2011)

Reports state that millions of Americans carry the defective Cystic Fibrosis gene however; most do not have any symptoms since the person with Cystic Fibrosis "must inherit two defective CF genes, one from each parent. An estimated 1 in 29 Caucasian-Americans have the CF gene. The disease is the most common, deadly, inherited disorder affecting Caucasians in the United States. It's more common among those of Northern or Central European descent." (PubMed Health, 2011)

The majority of children with Cystic Fibrosis are diagnosed by the time that they are two years of age however, a small percentage are not diagnosed until they are 18 years of age or older and are generally those with the milder form of Cystic Fibrosis. Symptoms of Cystic Fibrosis in infants include those stated as follows:

(1) Delayed growth;

(2) Failure to gain weight normally during childhood;

(3) No bowel movements in the first 24 to 48 hours of life; and (4) Salty-tasting skin. (PubMed Health, 2011)

Bowel-related symptoms include those as follows:

(1) Belly pain from severe constipation;

(2) Increased gas, bloating, or a belly that appears swollen (distended);

(3) Nausea and loss of appetite;

(4) Stools that are pale or clay colored, foul smelling, have mucus, or that float; and (5) Weight loss. (PubMed Health, 2011)

Reported as lung-related symptoms are those stated as follows:

(1) Coughing or increased mucus in the sinuses or lungs;

(2) Fatigue;

(3) Nasal congestion caused by nasal polyps;

(4) Recurrent episodes of pneumonia. (PubMed Health, 2011)

Symptoms in someone with cystic fibrosis include the following stated symptoms:

(1) Fever;

(2) Increased coughing;

(3) Increased shortness of breath;

(4) Loss of appetite;

(5) More sputum; and (6) Sinus pain or pressure caused by infection or polyps. (PubMed Health, 2011)

Later life symptoms include the following stated symptoms:

(1) infertility in men;

(2) Repeated inflammation of the pancreas (pancreatitis); and (3) Respiratory symptoms. (PubMed Health, 2011)

III. Pathophysiology

Cystic Fibrosis (CF) is described as an "inherited multisystem disorder of children and adults, characterized chiefly by obstruction and infection of airways and by maldigestion and its consequences." (Easy Pediatrics, 2012 ) CF is reported as inherited as "…an autosomal recessive trait. The CF gene codes for a protein of 1,480 amino acids called the CF transmembrane regulator (CFTR)." (Easy Pediatrics, 2012) It is reported that there are four "long-standing observations" considered pathophysiologically important as follows:

(1) Failure to clear mucous secretions;

(2) a paucity of water in mucous secretions;

(3) an elevated salt content of sweat and other serious secretions; and (4) chronic infection limited to the respiratory tract. (Easy Pediatrics, 2012)

Stated additionally in regards to the pathophysiology of Cystic Fibrosis is that there is "a greater negative potential difference across the respiratory epithelia of CF patients than across the respiratory epithelia of control subjects. Aberrant electrical properties were also demonstrated for CF sweat gland duct epithelium. The membranes of CF epithelial cells are unable to secrete chloride ions in response to cyclic adenosine monophosphate (cAMP) -- mediated signals and, at least in the respiratory tract, excessive amounts of sodium are absorbed through these membranes." (Easy Pediatrics, 2012)

IV. Etiology

More than 1000 potential changes can occur in CFTR, the gene associated with cystic fibrosis to result in cystic fibrosis however, it is reported that approximately 70% of patients with CF have the same defect or "F508" which is reported as a "deletion of 3 bases that causes the loss of the protein phenylaline." (Grossman and Grossman, 2005) Patients with a complete loss of the CFTR gene are stated to have a clinical phenotype representative of pancreatic disease, severe pulmonary disease, gastrointestinal problems, and interfiling in men with women having fertility problems. (Grossman and Grossman, 2005) Other patients have a partial loss of the gene with less severe phenotypes with gene defects classified into 4 or 5 categories stated to be dependent on the function and production of the gene. (Grossman and Grossman, 2005)

Grossman and Grossman report that typical manifestations of CF generally do not occur in patients who have at least 10% or more of CFTR function. There is stated to be lack of a 'definitive correlation" existing between the genotype and phenotype. (Grossman and Grossman, 2005) The majority of patients who have manifestations of CF have parents who do not have CF but are "heterozygotes or carriers of the disease." (Grossman and Grossman, 2005) A heterozygote is stated to have "1 dominant allele and 1 recessive allele." (Grossman and Grossman, 2005)

Where 2 persons who are heterozygous for CFTR have a child then this child may potentially have CF. (Grossman and Grossman, 2005) The Mendelian inheritance theory states that matings between carriers will results in 25% affected offspring or 25% chance of having a child with CF and 75% not having a child with CF. (Grossman and Grossman, 2005, paraphrased) There are a reported 7 to 10 million individuals in the U.S. who are CF carriers and who are not aware that they carry a mutated CFTR gene. (Grossman and Grossman, 2005, paraphrased)

V. Epidemiology

Assael et al. (2002) report a study on a population based in Veneto and Trentino involving neonatal screening for CF beginning in 1973 and ending in the early 1980s. The study is reported to have estimated the incidence in the region studied at 1 out of 2,650 live births each year. The data was analyzed on 593 patients born between 1938-2000 and living in the region who were followed by a single referral center.

The reported median time from birth to diagnosis of CF was 32 days. Median survival age was reported at 37.7 years with long-term survival to age 20 to 300 years and not being significant influenced by diagnosis mode, sex, or age at diagnosis for patients who were unscreened. Neonatal screening could not be attributed to improvement in long-term survival when compared with diagnosis by symptoms in early infancy. (Assael, et al., 2002)

VI. Diagnosis

There is reported to be a blood test available that assist in the detection of Cystic Fibrosis, which examines variations in a gene that causes the disease. Also used in diagnosing Cystic Fibrosis are the following tests:

(1) Immunoreactive trypsinogen (IRT) test is a standard newborn screening test for CF. A high level of IRT suggests possible CF and requires further testing;

(2) Sweat chloride test is the standard diagnostic test for CF. A high salt level in the patient's sweat is a sign of the disease;

(3) Chest x-ray and CT scan;

(4) Lung function tests;

(5) Tests measuring pancreatic function;

(6) Secretin stimulation test;

(7) Testing for Trypsin and chymotrypsin in stool; and (8) Upper GI and small bowel series. (PubMed Health, 2011)

VII. Treatment

Treatment of CF ideally will include an early diagnosis accompanied by a comprehensive treatment plan, which serves to improve the patient's quality of life and survival. Follow-up and monitoring are critically important and it is important as well that patients with CF be cared for a specialty clinics for CF. Children upon reaching adulthood should transfer to a CF specialty clinical for adults. Treatment for CF involves lung treatment including:

(1) Antibiotics to prevent and treat lung and sinus infections. They may be taken by mouth, or given in the veins or by breathing treatments. People with cystic fibrosis may take antibiotics only when needed, or all the time. Doses are usually higher than normal.

(2) Inhaled medicines to help open the airways

(3) DNAse enzyme therapy to thin mucus and make it easier to…

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