GENETIC ENGINEERING: Is It Morally Acceptable?
GENETIC ENGINEERING involves directly altering the genetic structure of an organism to provide it with traits deemed useful or desirable by those doing the altering. Genetic engineering of plants and animals has been going on since the 1970s, though attempts to introduce such traits through selective breeding has been going on for centuries.
The most straightforward use of genetic engineering involves producing a plant or animal with "improved" characteristics. In the case of agriculture, for example, genetic engineering has produced crop plants resistant to lower temperatures, herbicides, and insect attack, as well as tomatoes with a longer shelf life. A completely different type of genetic engineering involves transplanting a gene, usually human, from one species to another in order to produce a useful product. A patent already has been applied for to mix human embryo cells with those from a monkey or ape to create an animal that might have kidneys or a liver more suitable for transplantation to human beings. There seem to be no limits to the creatures made possible by genetic engineering--e.g., creating edible birds and mammals with minimal brain functions, including no consciousness, so as to avoid protests about the cruelty involved in raising and killing conscious animals for food.
Although particular instances of genetic engineering of plants and animals have caused some controversy, mostly because of environmental or health concerns, genetic engineering is a generally accepted practice. The major moral controversy concerns whether to allow directly altering the genetic structure of human beings. Genetic engineering done by altering the somatic cells of an individual in order to cure genetic and non-genetic diseases has not been controversial. Indeed, what is known as somatic cell gene therapy is becoming a standard method for treating both kinds of diseases. Unlike the genetic engineering used in plants and animals, somatic cell gene therapy alters only the genetic structure of the individual who receives it; the altered genetic structure is not passed on to that individual's offspring. However, now that large mammals such as cows and sheep can be cloned, it may be possible that genetic engineering done by altering somatic cells in human beings may be passed on to future generations of human beings.
Presently, somatic cell genetic engineering is limited to therapy--there has not even been a proposal to use it for enhancement. Clinical trials using human patients have demonstrated the feasibility of somatic cell gene therapy in humans, successfully correcting genetic defects in a large number of cell types. In principle, there is no important moral distinction between injecting insulin into a diabetic's leg and injecting the insulin gene into a diabetic's cells.
The most serious moral controversy concerns the application to human beings of the kind of genetic engineering used on plants and animals. This type of human genetic engineering, usually referred to as germ line gene therapy, is regarded by some as the best means to correct severe hereditary defects such as thalassemia, severe combined immune deficiency, or cystic fibrosis. Many believe, though, that genetic engineering to treat or eliminate serious genetic disorders--the practice of negative eugenics--will lead to the process being directed toward enhancing or improving humans, or positive eugenics. This slippery slope argument presupposes that there is something morally unacceptable about positive eugenics, but that has not been No one yet has provided a strong argument demonstrating that genetic engineering to produce enhanced size, strength, intelligence, or increased resistance to toxic substances is morally problematic.
Eugenics properly has a bad connotation because, prior to the possibility of genetic engineering, eugenics only could be practiced by preventing those who were regarded as having undesirable traits from reproducing. Genetic engineering allows for positive eugenics without limiting the freedom of anyone. The moral force of the objection that genetic engineering, especially positive eugenics or genetic enhancement, is "playing God" is that we do not know that there are no risks. A proper humility and recognition of limited human knowledge and fallibility is required for reliable moral behavior. A strong argument for concluding that genetic enhancement and perhaps even genetic therapy is morally unacceptable is that it risks great harm for many in future generations in order to provide benefits for a few in this one.
Arguments against eugenics
Two standard arguments have been put forward that even negative eugenics should not be practiced. The first is that it will result in the elimination of those deleterious alleles (alternate forms of a gene) which may be of some future benefit to the species. The argument is that the genetic variation of a species affords evolutionary plasticity or potential for subsequent adaptation to new and perhaps unforeseen conditions. To eliminate a deleterious mutant allele, like those responsible for cystic fibrosis or sickle cell anemia, could have some risk. It generally is agreed that the recessive gene responsible for sickle cell anemia evolved as an adaptive response to malaria.
This argument is false for two different reasons. The first concerns the nature of genetic maladies. For those based on the inheritance of recessive alleles, it is not the presence of two mutant alleles that causes the malady, but the absence of a normal allele. As long as a normal allele is present, the mutant ones do not cause a genetic disorder. In the case of sickle cell anemia, gene therapy for recessive disorders will work, even though the mutant and non-functional alleles remain. When it is possible not merely to add a gene, but to replace a non-functional mutant allele, the latter no longer will remain. No evolutionary problem is caused by eliminating dominant genes that cause serious genetic disorders such as Huntington's disease.
Almost all genetic disorders are caused by recessive genes, and it seems quite unlikely that there will be any serious attempt to eradicate these genes from the human gene pool, even if it becomes possible and desirable. The technology required must be applied on an individual basis with rather limited accessibility. Because it is a surgical procedure, germ line gene therapy would be done in a medical setting and on a voluntary basis. Although many couples might qualify for gene therapy, just a small number likely would elect to participate. For example, if germ line gene therapy involving gene replacement could be developed for Tay Sachs and was used to treat all embryos showing the disease, the frequency of the Tay Sachs allele in the entire population merely would decrease from 0.0100 to 0.0099 over a generation.
The second argument is an iatrogenic (produced inadvertently in a medical procedure) one. The claim is that, since it is impossible to draw a non-arbitrary line that distinguishes positive from negative eugenics by defining what a genetic disorder is, genetic therapy may cause more serious maladies in future generations than it prevents for the present one. However, genetic conditions like hemophilia, cystic fibrosis, and muscular dystrophy all share features common to other serious diseases or disorders, such as cancer. An objective and culture-free distinction can be made between genetic conditions that everyone counts as diseases or disorders and those that no one does. Even if there are some borderline conditions, it is theoretically possible to limit genetic engineering to those conditions about which there is no disagreement. The topic of what counts as a malady--in particular, what counts as a genetic malady--is important for it may affect not only what conditions will be covered by medical insurance, but which ones are suitable for gene therapy. If genetic engineering is used just to cure serious genetic maladies such as Tay Sachs, it is extremely unlikely that more serious genetic maladies will be created in the future.
While there is no theoretical reason for not using germ line gene therapy, there is a persuasive argument which concludes that all forms of germ line genetic engineering involving humans should be prohibited. This argument, similar to the one against genetic enhancement, claims that even genetic therapy risks great harm for many in future generations, and that there is not sufficient harm prevented to justify these risks. Genetic therapy, like genetic enhancement, not only is permanent during the entire lifetime of the affected individual, the transgene becomes inheritably transmitted to countless members of future generations.
New facts about basic genetic phenomena are being discovered--e.g., five human genetic disorders have been found that are based on mutations involving expandable and contractible trinucleotide repeats. This baffling and novel mechanism for producing mutations was unpredicted, and there currently is no complete explanation for its cause. Similarly, geneticists have discovered another novel and unpredicted phenomenon--genetic imprinting. For a small, but significant, fraction of genes, in humans and other species, the expression of the gene during early embryonic development varies according to its paternal or maternal origin. The biological role of imprinting and the molecular mechanism responsible for selective gene expression remain mysteries. Nevertheless, the effect of genetic imprinting and trinucleotide expansion may be critical in terms of carrying out germ line gene therapy. Problems might not be discovered until the third or fourth generation. Moreover, it seems likely that unpredicted future facts about basic genetic phenomena will be discovered which carry similar risks.
Given even this small possibility of significant harm to many, an analysis of risks and benefits indicates that germ line gene therapy would be justified just in cases of severe maladies, and then only if there were no less radical way of preventing them from occurring. Pre-implantation genetic screening, whereby embryos first are produced by in vitro fertilization, does provide such an alternative. At an early blastocyst stage of development, when the embryo is at the eight- or 16-cell stage, a single embryonic cell is removed and screened, genetically, for the presence of defective alleles. If analysis reveals that the fetus would develop a severe genetic malady, the embryo would not be implanted. If the embryo has no severe genetic malady, uterine implantation would be carried out so that normal development could occur.
Pre-implantation screening can eliminate essentially all severe genetic maladies that could be eliminated by genetic engineering. For those with religious or metaphysical beliefs that prohibit destroying any fertilized human egg, it should be pointed out that genetic engineering usually involves creating more fertilized eggs than one plans to use, since implanting of any fertilized egg, including a genetically altered one, often is not successful.
Consequently, pre-implantation screening eliminates the need for germ line gene therapy. The number of cases whereby both parents carry the genes for a rare deleterious recessive allele, such as cystic fibrosis, are microscopically small. Genetic engineering, then, is necessary only for improving or enhancing people by adding new genes for strength, intelligence, or resistance to pathogens or toxins. Genetic engineering to add improvements, rather than to eliminate defects, may give rise to serious social and political problems.
Moreover, gene therapy will be, for the foreseeable future, a very expensive procedure, so only the wealthy will be able to afford it. Germ line gene therapy probably comes as close as is humanly possible to guaranteeing that those families who can afford it will be able to perpetuate their social and political dominance. Thus, together with cloning, it may give rise to a genetically stratified society, as envisioned in Aldous Huxley's novel, Brave New WorM. Once this technology is well-developed, it can be used by societies in which those in power are not governed by ethical restraints. Individuals may be genetically engineered to provide various tasks--e.g., as warriors. Imagine a group of people engineered to be resistant to various poisonous gases. Still, these concerns, although genuine, are speculative.
On the other hand, scientists know from experience that cutting-edge technology generates pressures for its use. Consequently, it is likely that, if genetic engineering were permitted, the technology would be utilized inappropriately, employed even when a comparable outcome could be accomplished using a less risky method. There is justified concern that genetic engineering advocates will make claims that the risks are less than they really are and the benefits are greater than will be realized. It is at least disconcerting that proponents of germ line gene therapy do not talk at all of the far less risky alternative of pre-implantation screening.
If every scientist, administrator, and venture capitalist involved in applying and commercializing genetic engineering were appropriately thoughtful, there would be much less reason to prohibit development and application for those rare cases in which it could be the therapy of choice. However, based on the cited risks, there is insufficient potential benefit to justify any human genetic engineering. Until certain knowledge of the real risks and benefits associated with human genetic engineering has been obtained, the potential risks to all of the future descendants of the patient outweigh any benefit to a very small number of persons who might benefit. In the event of an unanticipated harmful outcome of genetic engineering using mice or corn, the transgenic organisms can be killed, but clearly this option can not be used with humans.
It takes just a few scientists who have convinced themselves that they know the risks are imaginary and the benefits are real for human genetic engineering to become a field in which researchers compete to be first. National and international recognition, prizes, awards, patents, grants, and other measures of status, wealth, and power are potent incentives to overstate successes and benefits, take unacceptable risks, and dismiss valid objections. The extraordinary loyalty of scientists to one another, resulting in their reluctance to interfere with any research project that their colleagues wish to pursue, makes it very likely that some misguided projects will be carried out.
Technology can not justifiably be used to provide benefits to only a few, even if such benefits are great. In cases where no great harm is being prevented and a large number of people may be put at significant risk, caution must prevail. Even if there is no chance of completely stopping germ line gene therapy, it may be possible to delay it long enough that the technology is developed that enables scientists to repair a gene, rather than replace it. Similarly, it might have been better if the building of nuclear power plants had been delayed until they were designed so that there would be virtually no chance of a nuclear explosion. Indeed, it might have been better to postpone building them until acceptable plans for disposing of nuclear wastes had been developed.
The Human Genome Project involves mapping the entire genome--that is, showing where each gene is located, not only which chromosome it is on, but where on that chromosome. This project was sold to Congress in a somewhat misleading way, its proponents claiming that, by finding the genes responsible for major genetic maladies like cystic fibrosis, as well as those that provide dispositions for standard maladies like cancer and heart disease, scientists better would be able to prevent and cure these conditions. That was true, but the whole Human Genome Project was not needed for this purpose. Most scientists were not so optimistic about it, and there was difficulty in lobbying Congress to appropriate all that money. The solution was to pick just those scientists who were on the optimistic fringe to testify before Congress.
The Human Genome Project also involves sequencing each gene--that is, showing how it is built up out of the base pairs that make up a gene. Most defective genes involve a change in a few of these base pairs, often merely one. Gene repair involves changing the base pair causing the problem. This form of genetic engineering has far less potential for disaster or misuse than the kind being considered. Further, the concept of gene repair reinforces the difference between gene therapy and gene enhancement. It would be inappropriate to regard making any change in a gene as repairing it unless that gene is both different from the standard form and results in some genetic malady. Limiting human genetic engineering to the repairing of genes dramatically would lessen the risks of such engineering while not preventing any of its therapeutic benefits.
Application of common moral reasoning to the question of human genetic engineering--both gene therapy and genetic enhancement--thus seems to lead to a natural solution. The present lack of knowledge should restrict genetic engineering to genetic repair. Such a limitation allows the prevention of all the evils of more expansive forms of genetic engineering while not incurring any of the risks. Given this alternative, allowing any more expansive form of genetic therapy or genetic enhancement does not seem morally acceptable.
Dr. Gert is the Eunice and Julian Cohen Professor for the Study of Ethics and Human Values, Dartmouth College, Hanover, N.H.
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|Publication:||USA Today (Magazine)|
|Date:||Jan 1, 1999|
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