Genetic Disorders of the Secretory Glands: Cystic Fibrosis - Essay Example

Cystic Fibrosis Cystic fibrosis (CF) is one of the deadliest genetic disorders of the secretory glands (Sheppard and Welsh, 1999, p. 23). It affects mainly the human digestive system, the liver, pancreas and the respiratory organs, mainly the lungs. The disease is mainly inherited via genes from parents to their offspring. As such, research indicates that any person who has the CF disorder must have inherited two abnormal genes that cause the disease with each parent donating either of the faulty genes. What is noted, however, is that a child may end up having the disease even if the parents do not have it. Other areas affected by the disease include the intestines, sex organs, and sinuses among others. Report indicate that the disease affects more than 30,000 children and teenagers in the US with high prevalence being seen among Caucasians who are affected to the tune of about over 60,000 patients according to Sheppard and Welsh, p. (23). Aetiology Cystic Fibrosis (CF) is a disorder caused by a fault in a gene called cystic fibrosis transmembrane conductance regulator (CFTR) that triggers the body to produce abnormal mucus that is thick and sticky (Bjourklund 2008, p. 4). Once the mucus has been produced, it clogs the respiratory track of the lungs and the pancreas. The buildup of mucus allows bacteria to start growing in the respiratory track leading to deadly lung diseases. If the bacteria are left to grow unstopped, serious lung problems that may be fatal might occur. The mucus may also block the ducts in the pancreas. It reported that if this occurs, the digestive enzymes that are produced from the pancreas would be blocked from reaching the small intestine (Bjourklund 2008, p. 4). This leads to digestive problems that may be fatal if left unattended. This is because pancreas-produced enzymes are vital for digestion. This implies that, without the enzymes, no digestion can take place within the small intestine. This also hinders absorption of proteins and fats into the body’s mainstream (Welsh and Smith 1995, p.16). In addition, the blockage of the track means that vitamins would pass through the body unabsorbed creative vitamin deficiency. The effect may make one develop swollen belly, bulky stool, severe pain, and intestinal gas. It is revealed that patients who suffer from CF disorder produce very salty sweat (Welsh and Smith 1995, p.16). This implies that such patients loose large quantity of salt from the body. Since salt is important as far as mineral balance is concerned, this balance of mineral content in the body would be lost making the patient develop other ailments such as dehydration, low blood pleasure, weakness, fatigue, heart stroke, increased heartbeat and sometimes death (Rosaler 2006, p.28). Anybody who suffers from CF syndrome is also said to be at high risk of suffering from diabetes, which is a deadly disease. Others end up developing a condition known as osteoporosis, which is characterized by thinning of the born. This is what makes such patients very weak and fatigued (Erlinger 2011, p.254). Since the disease also affects the sex organs of both males and females, it has been associated with infertility in men affected and difficulties in getting pregnant among women suffering from the disease (Orenstein 2003, p.42-44). Other symptoms associated with the disorder include weight loss, coughing, nasal congestion, fever, breathing problem, loss of appetite, increased sputum, high fever and delayed growth among children (Thursfield and Davies 2012, p.215). Molecular Basis (Mutation) As earlier stated cystic fibrosis (CF) is, a disorder caused by mutation of cystic fibrosis transmembrane regulator (CFTR) gene located along the arm of human chromosome. The gene is a type of protein that assists in the transportation of molecules such as chlorides, peptides, sugar, inorganic phosphates, and metal cations across membranes. CFTR also carries chlorides ions across the cell membranes of liver, lungs, pancreas, skin, reproductive organs, and digestive tracks. Thus, a defect in CFTR protein implies that there would be reduced or complete absence of chloride secretion in the body. The absence of chloride ion in the body results, in increased concentration of sodium in the body and water absorption as well as track surface liquid reduction. This impairs the removal of mucus resulting in CF syndrome (Monre 2001, p.14). Research indicates that approximately 70% of mutations seen among CF patients occur when the three base pairs of CFTR nucleotide sequence is deleted. This is because the deletion results in loss of phenylalanine amino acid in the protein. This is referred to as delta F508 since this amino acid is located at position 508. Findings also show patients who are homozygous for delta F508 mutation are the ones who develop the most severe symptoms of the disorder due to failure to transport the chloride ion. This triggers an imbalance of sodium and chloride ions required for maintenance on normal mucus layer that can be removed easily by the lungs and other organs. Once the imbalance is created, a thick, sticky layer of mucus develops that blocks the respiratory track leading to the lungs thereby trapping bacteria, which causes infections (Hodson, Geddes and Bush 2007, p.7-9). Factors Affecting the Cftr Phenotype It is reported that because CF is an autosomal recessive disease, therefore, for a mutated CFTR gene to manifest in a disease phenotype, the person must acquire the two copies of CFTR alleles. This implies that an individual who has only one of the muted genes would become a carrier of the disease. Such individuals would not show any signs of the disease despite carrying the trait of the CFTR gene. It is also noted that such individuals can pass the mutated genes to their children despite not having the CF disorder especially when they mate with a woman who happens to have traces of the CFTR gene. This explains why some parents may not reveal any signs of the disease in spite of it manifesting in their children (Hopkin 1998, p.17-19). Probability of passing CF disorder to a Child For CF disorder to occur, the two copies of the CFTR genes must be mutated (Hopkin 1998, p. 19). This implies that if both parents have the disorder, then it is automatic that their children will inherit the disease, which would manifest in phenotype. In addition, if both parents are carriers of CF, then there is a high probability of still passing the disease to children. This is because when a child happens to acquire a mutated CFTR chromosome from both parents, the child in question would end up having two mutated copies (Hopkin 1998, p. 19). In this regard, he or she would have CF disorder. However, if the child inherits one mutated chromosome from one of the parents and a normal one from the other parents, the child would end up becoming a carrier since he or she would only have acquired one mutated chromosome. Moreover, if the child inherits only normal chromosomes from the two parents, he or she would end up with two normal chromosomes, meaning he would be born free of the disorder (Hopkin 1998, p. 19). Diagnosis CF disorder is mainly diagnosed at birth in which babies are subjected to a screening test, sweat test and genetic testing (Rosaler 2006, p.33-36). Screening mainly entails performing a test on blood samples, in which case if the sample contains a high concentration of immunoreactive trypsin (IRT), the conclusion is that the child might be experiening CF mutation thereby calling for thorough analysis of the commonest mutations causing CF disorder. Sweat test, on the other hand, is done to determine the amount of salt in the sweat from which the result of the diagnosis is confirmed. In addition, children who show symptoms of intestinal blockage after birth may also be diagnosed few months after birth by subjecting them or CFTR test according to Monre (2001, p. 17-18). The disease may also be diagnosed during pregnancy in which either the father or mother or both are subjected to a screening test for the CFTR gene as a way of determining the risk of the unborn child having the CF disorder. For the mother, the test is usually done on the placenta or on the amniotic fluid using the chonic villus sampling. The test is sometimes performed on the fetus so as to establish the risk level (Rosaler 2006, p.33-36). Current Management Strategies Presently there is no known cure for CF disorder. However, certain strategies have been identified that can help in managing the condition. The strategies include performing regular exercise, physiotherapy of the chest, the use of salt supplements, and vitamin supplements, and the use of antibiotics. Other management strategies include a balance diet with high protein and fat levels, taking enzyme replacement drugs with food, and inhalation using nebulizer and compressed air pumps. However, patients are also advice to attend the nearest CF clinic for more professional advice (Welsh and Smith 1995, p.26-29). Other management strategies include avoiding smoking, fumes, dusty places, chemicals, smoke, and mildew. The patient should also engage in drinking plenty of water, clearing of mucus, and lung transplant among others (Welsh and Smith 1995, p.31). Future Directions for Therapy of Cystic Fibrosis Chest therapy is the most commonly applied therapy in the management of CF disorder. However, gene therapy is emerging as the best form of therapy likely to be adopted in future. The therapy involves putting the normal copy of CFTR gene onto the affected cells resulting in production of CFTR genes that are functional in the cells affected. For instance, research indicated that only 5-10% of normal copy of CFTR gene is enough to suppress manifestation of CF in lungs. It is for this reason that is preferred to chest therapy (Sheppard and Welsh, 1999, p.31-34). References Bjourklund, R. (2008) Cystic Fibrosis, Tarrytown, NY: Marshall Cavendish. Erlinger, S. (2011). Molecular repair of a defective CFTR protein in cystic fibrosis. Clinic and Research in Hepatology and Gastroenterology 35, 254-256. Hodson, M., Geddes, D., & Bush, A. (2007). Cystic Fibrosis. New York, NY: Hodder Arnold. Hopkin, K. (1998) Understanding Cystic Fibrosis. Hoboken, NJ: Univ. Press of Mississippi Press. Monre, J. (2001). Cystic Fibrosis. Mankato, MN: Capston. Orenstein, D. (2003). Cystic fibrosis: a guide for patient and family. Philadelphia, PA: Limpincott Williams & Wilkins. Rosaler, M. (2006). Cystic Fibrosis. New York, NY: The Rosen Publishing Group. Sheppard, D. & Welsh, M. (1999) Structure and Function of the CFTR Chloride Channel. Physiological Review 79 (1999): 23-45. Thursfield, R. & Davies J. (2012). Cystic Fibrosis: therapies targeting specific gene defects. Pediatric Respiratory Reviews 13(2012) 215-219. Welsh, M. & Smith, A. (1995). Cystic Fibrosis. Scientific American 273 (6): 52-59. Read More