GENETIC SCREENING

MIKE WETZSTEIN

Copyright 1996

Introduction

"Now we know, in large measure, our fate is in our genes." famous words that were stated by the co-founder of DNA's double helix structure, James Watson. In a large effect, in this day of modern science belief our fate is controlled by our genes. Ou r genes control our physical statue, our outward appearance, basically our entire bodily makeup is all determined by our genes. Mankind is at the edge of a new frontier in genetic medicine and gene therapy and how man advances into this field greatly dep ends on his ethics, morals, and the general acceptance of this new found knowledge. At the heart of the subject lies the controversy over genetic screening. Many questions arise such as; Who should be tested? Who should have access to the information? And most important, Does man have the right to correct any genetic defect no matter what the case?

Technical Aspects

A gene simply put is one of many discrete units of hereditary information located on the chromosomes. The chromosome consists of DNA, and the DNA codes for proteins in the human body, and in turn it is the protein that provides the phenotype for the i ndividual. Genetic screening provides a way to predict whether or not a specific phenotype will occur. There are many ways in which one can preform genetic screening. One is karyotyping. Karyotyping is a process in which a blood culture is obtained an d centrifuged to separate the different components of the blood. After centrifuging the supernatant fluid is discarded. A hypoosmotic solution is added, and the white blood cells swell up causing their chromosomes swell apart. The solution is then cent rifuged again, and the white blood cells are removed and placed on a slide and stained. The slide is placed under a microscope, the chromosomes are found, and a picture is taken of them. The picture is feed into a computer where the chromosomes are sepa rate as to their size and arranged in pairs to be studied and screened for any defects.

Other processes to locate defective genes in the human genome are the Polymerase Chain Reaction (PCR) developed by Kary Mullis and Restriction Fragment Length Polymorphisms (RFLPS), and a technique known as Southern Blotting. The DNA sample can be in creased in amount in a matter of a few hours by using the PCR technique. The DNA is then cut with a restriction enzyme, and the DNA breaks up into restricted fragments. A radioactive probe is added to the fragments that only bonds to certain codons in the DNA. The fragments are subjected to gel electrophoresis. The fragments move through the gel at different rates due to their different lengths. After the electrophoresis is done the DNA on the gel is denatured by heating and the single strands are t ransferred to membrane in a process known as Souther Blotting. The paper is then exposed to photographic film, and the radio active probe exposes itself onto the film which is then processed and studied to find any specific fragment or gene which is the cause of a condition or a disease.

There are many diagnostic tools to screen an embryo. One is amniocentesis. Ultrasound is used to locate the fetus and a small amount of amniotic fluid is removed. That fluid is then studied for any disorders. A nother test is the removal of some of the chronic villi. The physician removes some of the fetal tissue by inserting a tube into the cervix, and by removing a sample, studying it by karyotyping to discover any genetic abnormalities. A new procedure call ed preimplantation genetic diagnosis (PGD) uses eggs from the mother that are removed from her and than are fertilized with the fathers sperm in the lab. During a time period of three days from when the eggs are fertilized to when they are placed into th e mother by in vitro fertilization (IVF), the doctor can extract one or two cells from the embryo and study its genetic makeup to see if the embryo has any genetic abnormalities.

The Pros and Cons of Gene Screening

The first question that must be addressed is who should and who should not be screened. The prenatal amniocentesis screening for Tay-Sachs disease in Jewish populations is strongly recommended by geneticists to prevent the birth of a Tay-Sachs baby a ffected with this lethal disease. Judaism sees the approach as not acceptable because:

"The obligation with regard to procreation is not suspended simply because of the statistical probability that some children of the union may be deformed or abnormal. While the couple may quite properly be counseled with regard to the risks of havin g a Tay-Sachs child, it should be stressed that failure to bear natural children is not a Jewish legally viable alternative". (Hiller, 1981)

Judaism also has the viewpoint that no matter what the handicap that the fetus may have, it still has the ri ght to be born, and that the issue of abortion is only taken into consideration when the life of the mother is in danger.

Another area of concern is the economical impact of genetic screening. The process of IVF and PGD can alone cost up to $10,000, yet it costs more than $35,000 a year to treat a patient that has cystic fibrosis, a disease in which today many live into their 20's and 30's. Should the screening and the testing only be allowed for those who can afford it? Insurance companies usually refuse to pay for the screening because there is nothing wrong with the person at the time so why be screened. Or anothe r stand that the insurance companies take is that, if someone finds they are genetically susceptible to a certain genetic disease later on in life the insurance company will simply not cover that individual. Case in point, a small boy by the name of Jaco b Turner. After Jacob's mother died of a irregular heartbeat, tests revealed that Jacob had inherited the same condition from his mother. The condition, which is controlled by medication, caused Jacob not to be covered by his fathers insurance plan unti l recently this year. Dozens of states are now starting to pass laws barring insurance companies and/or employers from discriminating on the basis of a persons genetic makeup, genetic test information, or family history. However, these laws will not pro tect those who work for a self insured companies, which represent half of all employers from being charged a higher premium or being refused altogether. The Americans with Disabilities Act prohibits companies from rejecting job applications on the basis o f any genetic information.

Another important issue in the field of genetic screening is which genes should we screen. For early childhood diseases such as Tay-Sachs, hydrocephalus, and hemophilia, the answer seems to be a decisive yes. But, what about Alzheimer's disease, is it ethically right to tell someone that they have a predisposition to a disease that they will get when they get to the age of 60 or so. Would one want to know if they are carrying around a gene that this person will develop the disease later on in life . In the case of Huntington's disease in which the afflicted suffer loss of memory, mental acuity, and are unable to voluntarily stop moving muscles in their body. Would a person want to know such information and live with that information everyday of t heir life. Living in fear that the disease could or will strike at any time in the future. There is the belief of not telling the patient who would have a later occurring genetic disease as to, a cure may be found before the person develops the afflicti on. This would not place any unnecessary stress on the patient.

Another very important question that society must address is the screening of nondeliterious genes. These would include the genes which fall into the category of the obesity gene, the IQ gene, the Alcoholism gene, the heart disease gene, a depression gene, a hair color gene, a homosexual gene. The combinations of afflictions and their genes are endless. With the new method of the PGD, mankind would have a unforeseen power of affecting how he, or she procreates the species. Parents would no longer have to worry about what type of baby they would have. They could go into the clinic and create the baby that they would want, even down to the sex of the baby. Would it be right for a society to create designer babies because parents decide it is their right to chose what they want, and what would be best for their child?

But, does the embryo with the alcoholism or even the homosexual gene have any less of a claim to life than to say the "perfect" embryo. The beginning of life would be at the molecular level, the point when the sperm and the egg join. Which embryo ha s the right to live more? Who will choose which embryo has the right to live; the parents, the society, or the government? We cannot ignore the fact that the power of genetic screening does have the possibility of creating a lower class of genetically inferior individuals. If the information is made public, or if it is given to certain individuals, discrimination against those who are different than the rest could possibly arise. Racisms is the discrimination against races, than could one say that ge nisms would discriminate against those who would be not of the genetically preferred. Imagine a society that would consist of the upper, middle, and lower classes, also there would be the outcasts, the genetically inferior people.

Genetic screening and gene therapy are like a new found magic to man. With this great power man can now influence his own gene make-up, and control the genetic make-up of an embryo. But, how much can we control what is natural and what we would do t o make our society better. The attempt to rid the world of the genetic diseases that have plagued us to this point in time. In the past few decades great advances in the field of genetics have been made, but we have to stop and decide if what we are doin g is essentially right. We have in fact, treated the technology as "a child which has found a new toy". Yet man must be careful because it is not a toy, it is a powerful tool that could someday provide man with profound control of his destiny. But, w here will the control lead? For the betterment of our species? A way to rid mankind of all of the diseases that we alone do not like, or hate to see. Would it be right to rid the world of all the checks that nature has in place to control the populatio n? We alone are at a point now where the population is increasing to the breaking point where our own world cannot support us any longer. Genetic screening and gene therapy can throw the balance so out of the normal that mankind would be doomed to etern al extinction. Another question that must be answered is if it right for mankind to have this power of controlling his own genes, does man have the right to practice eugenics? According to the bible God created man in his own image. God created us and now we have found the key with which he created us and we can manipulate the key to develop better genes are we not playing god in our own sense? Mankind has taken the power away from our God. Is it right for mankind to do this, and to who do we now ans wer to? We have the tool to now control our destiny, no longer subject to the fate of our genetic makeup. Would man create a super race and commit to the practice of eugenics? If we breed a superior race of man is it not a possible that we would also b reed superior ambition, greed, hatred, and all that we view as the evils of our society. If we have found the gene for homosexuality, there could possibly be a gene for hatred, a gene for ambition, and so on.

How far will mankind proceed? A question we must all ask ourselves. At which point will man slow down and look back to see what has happened, analyze what it was we found, and what we have learned. We must proceed with caution, the right kind of mo rals, and mind set if we are to benefit society and mankind with this powerful tool of genetic screening and gene therapy.

References

Grady, Denise. 1995. Unnatural Selection, Vogue. v.185, n.10, pp230-234

Rubin, Rita. 1996. Do You Have a Cancer Gene, US World News and World Report, v.120,n.19, pp.66-73

Hiller, Marc D. 1981. Medical Ethics and The Law, Cambridge Mass. Ballinger Publishing Company.

Campbell, Neil A. 1993. Biology, The Benjamin/Cummings Publishing Company, Inc.

Berkowitz, Ari. Our genes,ourselfs? Obtained from the WWW 10/5/96: http://serendip.brynmawr.edu/~pgrobste/Berkowitz.html


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