Human Genetic Screening
Imagine the idea that you and your spouse are expecting a baby. You know that you both are carriers for ADA, a rare genetic immunodeficiency disease caused by lack of the enzyme adenosine deaminase. If your child received copies of the allele from both of you, he will have persistent infections and a high risk of early cancer, and may die in his first months of life (Grace par 10). Do you want to know if your child has the disease? If you do, you will undergo genetic screening, the testing for genetic diseases (Encyclopedia.com).
The Technical Aspects of Genetic Screening
Genetic screening began in 1934, in Norway, when a mother of two mentally handicapped children told a relative, a chemist, that her children's diapers had an odd smell. The chemist did some testing on the children's urine and found a biochemical abnormality, the children's urine contained too much of one chemical and not enough of another. They had inherited PKU, phenylketonuria, a disorder that causes the lack of ability to metabolize phnylalaine. Children suffering from this disorder are put on very strict diets in order to avoid mental retardation (Burge par 2).
Genetic screening is now used every day, when an amniocentesis is performed the fetus has just undergone genetic screening. Scientists can detect disease-baring mutations, test for genetic predisposition to diseases, and discover some physical characteristics and behavior traits that lie within your genes, all through genetic screening (White par 2).
Many types of genetic tests are available today. The most common type is newborn screening. Blood samples of newborns are tested for abnormal or missing gene products, some of these tests look for abnormal arrangements of the chemical bases in the gene, while other tests detect inborn errors of metabolism by verifying the absence of a protein that the cell needs to function normally. Prenatal screening is testing during pregnancy to determine whether a baby has a genetic condition or is at risk of one. Chorionic villus sampling and amniocentesis are the most common types of prenatal tests (Facts Sheet par 2). Carrier testing is another form of genetic screening. These tests tell a person if they carry a recessive allele for inherited disorders, also telling them if they are at risk of passing that allele onto their children. Carrier tests are helpful in early detection, diagnosis, prognosis, and treatment of the disorder one may be carrying. A third type of test is predictive gene testing. These tests identify people who are at risk of getting a disease, before any symptoms even appear. Symptomatic testing is done on those with specific medical findings, physical features, or developmental problems. This test helps attain correct diagnosis and a plan of treatment. All of these tests look for abnormalities in whole chromosomes, in short stretches of DNA within or near genes, and in the protein products of genes (Understanding Gene Testing).
Genetic screening is also done in the form of DNA fingerprinting and identity testing. This testing takes advantage of the fact that the DNA of each person, except identical twins, is different (DNA Fingerprinting par 2). There are two methods of DNA fingerprinting. The first is Restriction Fragment Length Polymorphism (RFLP). In this procedure small DNA fragments are removed from the molecule by enzymes. Radioactive probes bind to the DNA areas that are used to establish identity, and X-ray film detects the pattern. The film is then developed and the fingerprint is compared to other samples. RFLP may take several weeks to complete and relies on large samples that must be uncontaminated by any other DNA fragments. The second, less time-consuming test is Polymerase Chain Reaction (PCR). This procedure uses repeated cycles to reproduce a target area of DNA until enough copies are available for analysis.
Genetic screening is also used in paternity testing. In this procedure, samples from the mother, child and suspected father are tested. Since every child inherits half of its genes from it's mother and the other half from its father, by examining the mother's and child's genetic markers, it can be determined what genetic markers must come from the father. If the suspected father does not show two or more markers necessary for paternity, he is excluded. If he shows all the markers, mathematical analysis is done to determine the likelihood of him being the father (Analytical Genetic Testing par 1-4).
The Pros and Cons of Genetic Screening
Genetic screening is a widely controversial issue in the world today. There are many positive and negative aspects of screening. One of the positive aspects of genetic screening is the fact that early detection of any type of disease of disorder is usually much less expensive when it comes to treatment of that disease. Another positive aspect is the idea that if you are genetically screened for heritable disorders before you decide to have children, you will know if you are a carrier for those disorders and be able to decide if you want to take the risk of passing that allele on to your children or if you want to chose another method of parenting, such as adoption. Genetic screening also helps people that know a heritable disease runs in their family. These people can undergo screening to tell them if they are likely to have the disease later on in life. In a study of patients at risk for Huntington disease, findings showed that knowing the results of the test, even if they were at high risk of disease, reduced patient uncertainty (Jones par 11). DNA fingerprinting gives criminal investigators an edge when it comes to solving a wide variety of crimes from burglary to rape. Just a hair left at the crime scene can help in identifying suspects. Paternity testing is very helpful when it comes to single mothers seeking child support and men who want to know if they are actually the biological father of the child.
Although there are many pros to genetic screening, there are just as many, if not more, cons to screening. Financial aspects are one con of screening. Even though early detection is usually cheaper by means of treatment than later detection, genetic screening is not a small expense and in most or all cases, insurance companies will not cover the expense. Another issue of screening is the idea of privacy. If you are screened for a genetic disorder and you find that you are at high risk of developing that disorder, whom do you have to tell and whom does your physician have to disclose this information to? Does your family have the right to know? What about the mighty insurance company? If they find out about this disorder they are likely to drop your coverage, and not many insurance companies will be willing to cover you. Your career may also be in jeopardy if your employer catches wind of your likelihood of a disorder. There are also technical limitations to genetic screening. No test is 100% accurate in implicating whether you are at high risk or low risk of the disorder. A mistaken result could lead to many different situations, which wouldn't need to be dealt with if the test was correct in the first place. Another surfacing idea is humans playing God . With genetic screening, parents are able to find out a lot about their unborn child, if they find something they don't like, they have the freedom to abort the child. Is it right that we can pick and choose the traits of our children? An additional con to genetic screening is the psychological effect it may have on a person said to be at high risk for developing a disorder. True, a study did show that most patients were relieved; what about the one's that weren't so relieved to know? In the case of DNA fingerprinting and paternity testing, these test are not 100% accurate and can lead to great financial (in child support cases) and psychological turmoil.
I have many concerns when it comes to genetic screening. I feel that screening for detection of disease and early treatment or prevention is an excellent concept, although the psychological well being of those tested is a concern to me. I think that if people know exactly what is in store for them in the future, they may be less apt to make the most of the present. I think that knowing you are likely to develop a serious genetic disorder could cause serious damage to your family and social lives and to your career. However, knowing what might happen could be a huge relief to some people. Before allowing genetic screening, patients should undergo a mandatory psychological screening. I do think that you have the right to know what your genes hold if you think you can handle the results. However, I don't think anyone else has the right to know this information. It's your body and your private life; you have a right to know what is in store for you, but you should be the one who decides if others need to know. I especially do not like the idea of parents "designing" their children. If you are blessed with the ability to have children, you shouldn't take advantage of that ability by throwing away the ones you don't want. Prenatal testing is important for the health of baby and mother, not to determine whether the baby has the correct hair or eye color. It is obvious that the perfect human being does not and will never exist, people need to realize this and quit trying to manufacture their own "perfect" superhuman. Overall, genetic screening is an exceptional process when done accurately and within ethical standards.
Grace, Eric S. "Better Health Through Gene Therapy." The Futurist. Jan-Feb 1998, v32, n1, p39 Obtained from NDSU Webpals.
Jones, Valerie A. "In the Same Boat." The Journal of the American Medical Association. Nov 4 1998, v280, n17, 1537. Obtained from NDSU Webpals.
White, Mary Terrell. "Making Responsible Decisions." The Hastings Center Report. Jan 1999, V 29, p14. Obtained from NDSU Webpals.
Website #1: Access Excellence. "Understanding Gene Testing." Obtained from the WWW: http://www.accessexcellence.org/AE/AEPC/NIH/
Website #2: Analytical Genetic Testing Center. "What is a paternity test?" Obtained from the WWW: http://www.geneticid.com/WE01001.htm
Website # 3: DNA Learning Center. "DNA Fingerprinting." Obtained from the WWW: http://vector.cshl.org/resources/aboutdnafingerprinting.html
Website #4: Encyclopedia.com.1994. Obtained from the WWW: http://www.encyclopedia.com/articles/04986.html
Website #5:Healthline Magazine. "Genetic Screening. " August 1994. Obtained from the WWW: http://www.healthline.org/articles/oldfiles/hl940804
Website #6: Human Body. "DNA in Criminal Investigations." Obtained from WWW: http://www.mhhe.com/biosci/ap/dynamichuman2/content/humbody/reading24.mhtml
Website #7: Human Genome Education Model Project II. "Genetic Testing Fact Sheet." Obtained from WWW: http://www.dml.georgetown.edu/hugem/FGT.htm
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