Apoe Screening Test - Literature review Example

Apoe Screening Test Apolipoprotein E (Apoe) is an important multifunctional protein responsible for transporting the cholesterol via the cell membrane (Alfred, 2002). The metabolism of apolipoproteins in humans varies and depends on two genetic polymorphs by synthesizing Apoe (Muller, 2003). Protein apolipoprotein E is synthesized by the gene Apoe. The gene has three forms: E2, E3, and E4. A genetic test can be carried on Apoe to the check the possibility of a patient developing Alzheimer disease that is highly likely in patients with the E4 form of the gene. Apolipoprotein E is also believed to have some association with atherosclerosis, coronary heart disease, and diabetes. Apoe screening is a predictive test that tells the possibility of Alzheimer disease in a patient (Williams, 1990). This screening technique is also recommended for brain injury patients and can be used in studies of high potential risk cardiovascular persons (Roy, 2004). Testing the Apoe genotype plays a predictive role in dealing high-risk sports athletes to minimize likely damage factors (Jordan, 2005). This essay with help of adequate scientific knowledge will determine the suitability of Apoe screening and relation of the apolipoprotein to another related disease. Atherosclerosis refers to the hardening of the arteries, which occurs when cholesterol and fat build up in the artery (Gavan, 2005). Over time these hard structures may form plaques that cause problems through the body. Hardening of arteries is associated with aging. It starves the tissues of blood and oxygen that may result in heart attack and stroke (June 2005). At the young age, atherosclerosis can be related to increased cholesterol levels. Other risks of atherosclerosis are diabetes, high blood pressure and genetic inheritance of the hardening arteries genes. Atherosclerosis can be associated to the apolipoproteins E. All likely relationships of Apoe genotype with atherosclerosis have been reported earlier. Presence of atherosclerosis was found to be most probable to the carriers of E4 Apoe as compared to the carriers of Apoe E2 and E3 (Simons, 2005). An autopsy study in young adults who had died from carotid artery atherosclerosis confirmed the susceptibility of the alleles. An observation that Apoe E2 carriers have higher serum levels of Apoe and HDL (High-density lipids) cholesterol has opposed to Apoe E4 was noted. Various isoforms exert different antioxidant effects that influence the possibilities of the atherosclerosis occurrence in an individual (Lyn & Stevenson 2002). By and large, evidence from studies accrued from human beings supports that Apoe gene plays some role in atherosclerosis. Considering that Apoe proteins are concerned with the transport of cholesterol it easily points to the proposition above. A role in reverse cholesterol transport is the liable explanation to cause of atherosclerosis by the Apoe genes (Sammy, 2001). Cholesterol, waxy steroid fat, when deposited in the arteries they reduce its diameter and hence block blood passage causing the arteries to harden (Argwings, 2003). This deposition of cholesterol was found to be common in persons with the E4 allele of the Apoe (Mahler, 2005). This is the more reason atherosclerosis could be associated to the apolipoproteins. However, it is not obvious that the presence of an E4 allele is an automatic indication that one will automatic be affected by atherosclerosis rather it is the indication of high likelihood. Atherogenetic nature of the Apoe protein is however significant, though a direct connection has not yet been established. Apoe screening, in this case, it holds some hope in assessing the connection that is almost visible but invisible. Alzheimer’s disease is an irreversible, continuous brain disease (Martins, 2005). It is characterized by occurrence of plaques and tangles and loss of connection between the brain’s nerve cells, and death of the nerve cells. Alzheimer's occurs in two types, the early -onset, and the late-onset. Early-onset Alzheimer's disease is an example of a mutated gene disease. They are believed to be caused by gene disorders as a result of mutation. Early-onset Alzheimer’s disease is common to people between ages 30 to 60 (Leigh, 2006). The early-onset disease has no known cause but it is alleged to be caused by inherited genes. Genes play an exceptional role in human beings. Their role in Alzheimer's disease cannot be ignored. Studies centered on Alzheimer’s disease and apolipoproteins E has caused exhilaration in the research centers and the general public. Genes function together with environmental processes to determine traits inherited from our parents (Roberts & Taylor, 1990). Sporadic Alzheimer’s disease is far more common. It is related to Apoe gene found on chromosome 19. The Apoe genes occur in various forms but only three are significant in this case: Apoe2, Apoe3, and Apoe4. People who are carriers of Apoe3 and Apoe4 are affected by both alleles at the same time (Peters, 1994). Allele Apoe4 just like in atherosclerosis are the most susceptible to Alzheimer’s disease. In fact, allele E4 has a susceptibility of 75% making it a high-risk factor (Ann, 2009). In Apoe testing blood test is done to identify which Apoe allele a person has (Harrington, 1985). The blood test, however, does not give a yes or no as to whether a person has Alzheimer disease; instead, it gives the only possible through analysis of the gene alleles in a person. Apoe testing is, therefore, more useful in research context since it can give predictions to a large population on the risk they face, rather than an individual condition (Mayer, 2001). Coronary heart disease is a condition where thick plaque develops inside the coronary arteries, which takes blood to the heart muscle (Peters, 2007). This is mainly caused by hardening of arteries, which take blood to the heart. When this condition occurs, a person is most like to suffer the heart attack and angina. An angina is a chest pain where one feels squeezing or pressure in the chest (Jayne et al 2000). A heart attack occurs in instances where the supply of blood and oxygen to the heart is cut off. Apolipoproteins E is known to have some influence on coronary heart disease. Apolipoproteins E is polymorphic in nature. Different varieties of Apoe results as a result of linkage to low-density lipids that form varying levels of lipids and lipoproteins that poses risk to coronary heart diseases (Wilson, 1993). Apolipoproteins is an important part of lipoprotein metabolism. It facilitates lipoprotein binding to low-density lipids (Young, 2008). Misfits in the Apoe proteins could affect their knack to bind to low-density lipids that lead to excess deposition of cholesterol into the blood. In human beings, the gene coding for Apoe is located on chromosome 10 (Hanna, 2001). The major effects of genetic mutations are in the regulation of blood-cholesterol levels (Wilson, 2005). Changes in cholesterol levels are the directly proportional to the emergence of the coronary heart disease. Cholesterol-lowering leads to minimal coronary heart disease risks whereas cholesterol increments lead to higher risks of coronary heart disease. Three alleles in the Apoe gene account for gene polymorphism and results to six combinations. A combination of E4/E4 is the most probable to cause an excess deposition of cholesterol that leads to coronary disease (Lewis, 1980). Apoe testing will establish the gene allele combination an individual contains and predict their chances of coronary heart disease. In the testing, all other factors that cause coronary heart disease will be examined to ensure that the conditional solely originates from gene polymorphism. In this type of test, the blood samples of individuals are taken, the gene combinations analyzed to deduct the risk of coronary heart disease (Jason, 2004). Diabetes refers to a metabolic disease of high blood sugar (Daniels, 2005). High blood sugar is because of the failure of the pancreas to create adequate insulin or unresponsiveness to insulin produced by the cells (Mark, 2009). Diabetes mellitus results from body fails to produce insulin and a person is forced to take insulin tablets physically to supplement their bodies. Diabetes mellitus relates to old age and is the most typical. Diabetes relates somehow to apolipoproteins. In recent studies, a relationship has been noted between diabetes and Alzheimer’s disease. This relation has sparked discussion on a possible relation between diabetes and apolipoproteins. According to Willis (2004), the relationship between diabetes and Alzheimer disease is particularly stronger among carriers of Apoe E4 allele. When an Apoe test is carried it is likely to predict the possibility of Alzheimer’s disease and diabetes as well. Apolipoproteins E plays a major role in lipid metabolism and brain physiology (Cathy &, Leans, 2001). Diabetes is closely related to dementia, though studies indicate that results of comparing dementia and diabetes are not consistent. Lipid metabolism plays a major role in dementia hence an indirect relationship between apolipoproteins and diabetes. This is a sign that the upshots of the gene polymorphism, which result in a combination of the allele, E4 have a significant effect on the vulnerability of a person to diabetes. In the study of an apolipoprotein E testing, all cardiovascular factors, Alzheimer’s and diabetes are found to be in relation. Results from various studies are varied. However, what comes out clearly is that the above conditions could arise from a common cause such as gene mutations in the apolipoproteins E. Coronary heart disease, diabetes, Alzheimer's and atherosclerosis are observed to have some prevalence in persons with the E4 combination of alleles (Dawson, 2004). This is an indication that there must be a common factor that cuts across all the conditions, hence a huge likely hood of a connection. Apoe testing in this instance will play a big role in researching the interconnectivity of these conditions. Apoe test is mostly used for research; its clinical usage has proven to be of minimal help. It is recommended for use to test and diagnose the probability of the late-onset Alzheimer's disease in adults who show symptoms of the disease. It is referred to as risk factor testing since it only indicates the possibility of risk rather than specific diagnostic of the disease (Daniels, 2001). If a patient with dementia is diagnosed and found to be having Apoe4, then dementia might be caused by the Alzheimer’s disease (Michaels, 2007). Currently, in the medical sector, there are no definite diagnoses to Alzheimer’s disease during life. This has made physicians to carefully and accurately carry out clinical diagnosis of Alzheimer’s disease through nullifying other potential causes. Apoe genotyping is ordered under different circumstances such as when a patient has quite notable high cholesterol and triglyceride levels, when family members have Apoe e2/e2 and the doctor wishes to assert if a member is at high risk of heart disease and also when one develops xanthomas, yellowish skin lesions, that is suspected to be type 3 hyperlipoproteinemia (Hughes, 2003). Lack of adequate knowledge on the Apoe testing results has at times proven fatal. Many people cannot interpret correctly what the results mean. People with Apoe genotype of e2/ e2 have higher chances of developing premature vascular diseases. However, there is a possibility that they might never develop the disease at all. Those with genotype e4/e4 are at the highest risk of atherosclerosis (Daniels, 2001). Those who are symptomatic and have a single component of the e4 allele are likely to have Alzheimer’s disease (Kevin, 1992. However, this is not to mean that those with an e4 allele are definitely going to develop the disease. In fact, there is a huge possibility that they may end up not contacting the diseases at all. An Apoe e3 means there is normal metabolism and hence no genotypic impact (Williamson, 1985). In that connection, it is important for the patient to understand that Apoe testing only provides additional information to a condition. Alzheimer’s disease cannot be diagnosed directly and treated using this technique. Alzheimer’s disease is only examinable when the patient is dead and their brain tissue is used. . The UK government should not introduce the Apoe screening programme. The main reason behind this stand is informed by the small level of awareness among the broad public. Most people still do not understand the Apoe testing and screening technique. When a person is diagnosed with an E4 allele they will most likely run into a conclusion that they have contacted Alzheimer disease. This will lead to situations where people panic and give up in life yet they might never actually contact the disease. The incompleteness of the technique is also unsatisfactory; most patients cannot bear a diagnosis without treatment. This will likely make it difficult to run the programme in the UK In conclusion, this technique should be abolished since it bears little significance to the treatment of Alzheimer disease and other cardiovascular diseases at the personal level. Prediction with no treatment is a major disadvantage to the Apoe testing. In fact, it may prove disastrous since those people with a higher likelihood of contacting the diseases might run into emotional meltdown and despair. Furthermore, this technique also violates confidential issues in a number of ways which may negatively affect the patients. Once an individual is diagnosed, a medical report is drawn. The condition of the patient is no longer private and this exposes the patient to a lot of bias. They might be discriminated against in job places by employers and insurance firms. Therefore it is advisable to keep the technique out for the time being until more a complete technique is formulated. References Alfred, M, 2002, Introduction to cell microbiology: types of proteins, Avery Publishers, New York. Ann, B, 2009, Introduction to genetics: types of alleles, Clavers Publishers, Boston. Cathy, D, & Leans, D, 1990, Fat Formation, Sparks Publishing Corporation, Boston. Daniels, Albert, 1983, Genotyping in human beings, Pipers Publishing Press, Texas. Daniels, H, 1995, Diabetes, and hypertension: control and prevention, Gillian Publishers, Denver. Daniels, R, 2003, Brain structure: functions of the brain. Dave and Brothers Publishers, Miami. Dawson, Harry, 1992, Genetic isoforms combination: nature of alleles, Kindlers Publishers, New York. Hanna, D, 2000, Blood test technology: blood group. W.A.R.P Publisher Association, New York. Harington, D, 2001, Gene coding: genetic combinations, Plumbers Publishers, Paris. Hughes. M, 1988, Causes of hyperlipoproteinemia, Zoons Publishers Corporation, California. Jason, K, 1986, Controlling Heart Related conditions, CND Publishers, Langley. Gavan, Allan, 2005, Heart conditions: causes of atherosclerosis, Mangers Publishing Firm, Boston. Jayne, W, 2000, Causes of angina: diagnosis and treatment, Dude Publishers Association, California. Jordan, C, 2001, Genetic variations: types of the allele, BNG Publishers, New York. June, S, 2009, Causes of the heart attack: vessel constrictions, Lions Publishers Corporation, Denver. Kevin, P, 2003, Symptoms of Alzheimer’s: discussion and analysis, Lens Publishers Press, Beijing. Leigh, G, 2006, early onset Alzheimer's disease: causes and symptoms, Latitude Publishing Corporation, Rome. Lewis, K, 1980, cardiovascular disease: diagnosis and treatment, A & B Publishing Press, Wales. Lyn, E., & Stevenson, R, 2002, Nature and types of alleles: types of oxidants, Cookers Publishers Press, Dortmund. Mahler, D, 2005, Formation of cholesterol: lipid metabolism, Equinox Publishers, California. Mark, L, 1989, Diabetes mellitus: Type Two diabetes, Apache Publisher Corporation, Texas. Martin. W, 2004, Apolipoprotein and Gene Polymorphism, KNM Publishers Associates, Paris. Michaels, B, 2008, Introduction to body vessels: arteries and veins, Archive Publishing Firm, Philadelphia. Muller, G, 2002, Introduction to disease and genetics, Retrieved from http://www.diseasesource.com/htm.edu Peters, F, 1992, Coronary heart disease: causes and symptoms, Ansad Publishers, Georgiana. Peters, L, 2010, Introduction to genetics: genotyping, Pluto Publishing Press, New York. Peters, M, 1987, Apoe testing: process and requirements, Petersen Publishers Association, Alabama. Robert, Y, & Taylor, T, 1990. Sporadic Alzheimer’s disease, Markers Publishing Firm, Rome. Simons, J, 2001, Cell metabolism: nature of profits, Speakers Publishing Press, Washington, DC. Sammy, T, 2001, Lipid formations: roles of cholesterol, Peak Publishing Firm, Michigan. Williams, G, 1990, Inheritance, and genetics: polymorphism and cell mutation, Best Publishing Press, London. Williamson, Caesar, 1988, Impact of lipid metabolism, Maximum Publishing Corporation, London. Willis, Steven, 1999, Managing Alzheimer’s disease: counseling, Myriad Publishing Firm, Orland. 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