Human Gene Therapy

Kessa Hays

Copyright 1998

Human gene therapy is a fairly new study in the biology and medical fields. The value of gene therapy extends from curing horrible genetic diseases, to enhancing our bodies physical appearance, and to being a new drug delivery system (1). The results from gene therapy seem almost limitless once it becomes common practice, but for right now there are still some technical aspects to overcome. Gene therapy is also a highly controversial topic in some aspects.

One of the major goals of gene therapy, and could be the most important, is replacing defective or missing genes with healthy ones. The possibility of eradicating genetic disease and giving someone a normal life is inspiring. There are a couple options available for replacing the missing or defective genes in the cells; one way is using a disabled virus or a retrovirus to implant the good gene into the cells. There are some problems using a virus when it comes to replacing many genes, and one of the recent techniques to overcome this is using a man-made chromosome. The chromosome, called human artificial chromosome, is duplicated and passed along just like a normal one (5).

The first disease that was approved for gene therapy was ADA deficiency, in which the body lacks production of adenosine deaminase. Adenosine deaminase is important for the proper function of the immune system; people who lack this enzyme have a poor immune response to disease and normally die within the first few years of life (1). The procedure used to correct this disease was to make regular infusions of the patients own genetically corrected T-lymphocytes (1). First the lymphocytes were taken from the patients and encouraged to grow using a disabled mouse retrovirus as a vector. Those cells that had successfully accepted the new gene were removed and encouraged to grow for some time, and then the infusions to the patient began. Two children were used in this first study and both have shown an improved immune function. More recently scientists have treated one of the children with gene-altered bone marrow stem cells, which will actually produce genetically correct T-cell within the child (1).

Other diseases have been studied using gene therapy such as cystic fibrosis, familial hypercholesterolemia, many cancers, and HIV (1). There are even hopes of using gene therapy as a vaccine against cancer and HIV. Success with some of these diseases doesn’t seen to be quite as successful as with the ADA deficiency so far.

To treat cancers such as brain tumors, one of the procedures being studied is adding a gene via a disabled virus that makes the cancer cell susceptible to other drugs (2). The reason for making the cancer cells susceptible to other drugs is that many times it is impossible for a surgeon, no matter how skilled, to remove all of the tumor. By using a vector that only infects rapidly dividing cells, only the cancer cells in the brain will be infected because the other cells don’t divide. Using this technique gives the patient a better chance of getting rid of all the cancer. This procedure has had mixed results so far, and some believe that it is not real benefit because sometimes many of the cells don’t pick up the gene that weakens the cell for drug attack (2). The type of brain tumor used in this study was a glioblastoma, a very destructive, fast growing tumor. The odds for conquering a brain tumor such as this is about one in a hundred people. During the phase one trial of ten patients nine died within three months to a year which is about the expected amount of time from radiation and other treatments. One did defy the odds and was still alive five years later (2). The phase to trial was done on 31 patients and the average survival was seven months (2). However, six of the patients were still alive three to four years later, and some argue that this study does show a great improvement with the gene therapy treatment. A phase three trial on 250 patients has been set up to distinguish if the therapy really is a help or not (2).

Similar techniques are being used on other diseases and have shown a fair amount of success. One success story is from Elizabeth’s Medical Center in Boston where ten patients had such severe peripheral artery disease they were in danger of losing their legs (2). The procedure involved implanting a gene for a hormone that stimulates the growth of blood vessels. The majority of the patients grew collateral arteries that bypassed their blocked arteries, and nine of the ten improved so much that amputations were either avoided or reduced to a toe (2).

The major controversy involved in gene therapy is how far should the manipulation of the human gnome be taken. most people would probably agree with correcting diseases that cause death or cause a person to not function normally, but the major arguments begin when people begin talking about using gene therapy for enhancements, such as cosmetic purposes, making someone taller so they can play sports, or genetically engineering the perfect baby.

There are those who believe that because society already allows people to change or alter their looks by using things such as plastic surgery, liposuction, growth hormone for below average juveniles, radial keratotomy, and tattooed makeup, why not allow use of gene therapy as well if it can accomplish all of these things and the effects are lasting? Gene therapy could even be used to stop the use of drugs for appetite suppressants. To the many people who suffer from hair loss and to the juvenile who is six inches shorter than the rest of the class, enhancement procedures are not a trivial matter (3). Everyone in our society likes to look and feel good about themselves, and we have a good number of cosmetics, cosmetic surgeons, and gyms to prove it (3).

On the pro enhancement side of the argument, they want to know just who or what determines how a “serious disease” should be classified if only those who have a serious disease are eligible for treatment (3). For example a person that is largely obese is most times considered to have a serious disease whereas someone who is thirty to forty pounds overweight has only a mild disease and then someone who is slightly overweight wouldn’t be considered to have a disease at all (3). Therefore if one of these people is capable of getting treatment why can’t all three because most people like to look good in a pair of jeans.

In the future it may even be possible for parents to have made-to-order babies. They could have the perfect child of their dreams from eye color and stature to how intelligent the child is (4). The pro side would argue that the parents have every right to have the perfect baby of their dreams; and whose to argue with the parents over the well being of their child?

On the other hand there are those who argue that use of gene therapy for enhancement should not be allowed (3). There are several reasons for this. One being many medical reasons such as the new gene could be overexpressed and produce an overabundance of the desired protein which could be harmful in large quantities (1). Another medical risk is the viral vectors which could cause inflammation or an immune response (especially if repeatedly used); the vectors could also be transferred to other individuals or into the environment (1). A third medical concern is that the new genes could be carried into the germ cells producing heritable changes (1). The last problem is that the desired gene may not end up in the correct place in the DNA. This last medical problem could activate oncogenes or inactivate cancer suppresser genes causing cancer or it could cause other problems.

There are also some moral reasons for this group to oppose the use of gene therapy for enhancement. One is that it could possibly create a greater gap between classes if only the rich can afford it (1). Using gene therapy for enhancement could also discriminate against those who are either short, unattractive, or merely of average intelligence (1). Some people are also concerned that people may be coerced or even forced to have gene therapy if it makes them less susceptible to work toxins, or to fit other workplace environments from physical appearance to tolerating harsh environments.

There is also a slight leftover fear from WWII when the Nazis were trying to form the perfect race by culling out the weak minded or genetically imperfect individuals (4). Lewis Wolpert, a biologist at University College in London, called solving the mystery of the human embryo “Frankenstein’s quest” (4). Granted technology is not advanced enough for some of these things, but with its continuing progression these controversies may not be too far away.

For myself, I can see using gene therapy for curing disease, especially those diseases that are passed down from generation to generation. I think it would be pretty rough to want children, but having to worry about whether or not they will turn out healthy would make it difficult to decide to have them. As far as the enhancement issue I think people are starting to walk off into the Frankenstein issue. Each of us are given a number of physical and emotional obstacles to overcome, and to overcome them makes us a stronger individual. Every person that you meet is an individual being who has personality traits, intelligence factors, and physical traits that are different from you. If every person could pick out the exact traits they wanted in their children I think everyone would begin to look the same. Who doesn’t want to be tall, thin, intelligent, and good looking? However once everyone looked the same the definition of what’s beautiful would probably change to whatever is not considered the norm because different denotes special. What would life be like if by doing this everyone ended up with similar personalities? That would make life pretty dull. Variety has been said to be the spice of life, and frankly I agree. As far as picking out exactly how children would look, what if the child decided that they didn’t like it after the parents went through all that trouble to make the perfect child. After all the grass is always greener on the other side, and even super models have flaws they would like to correct. All people, even those who are disabled in some way, have something to offer whether it’s the contributions of an Einstein or the smile a friendly disabled person gave you that allowed you to remember how to feel as a human.


1. National Cancer Institute, Questions and answers about gene therapy. Obtained from the WWW 11/2/98:
2. Goldberg, Jeff. A head full of hope. Discover April 1998, v19, n4, p70
3. Miller, Henry I. Gene therapy for enhancement. The Lancet July 30,1994, v344, n8918, p316
4. Radford, Tim. Designing the next generation? World Press Review March 1994, v41, n3, p22
5. Kher, Unmesh. A man-made chromosome. Discover January 1998, v 18, n1, p40

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