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Genetic enhancement refers to the use of genetic engineering to modify a person's nonpathological human traits. In contrast, gene therapy involves using genetic engineering to alter defective genes or insert corrected genes into the body in order to treat a disease.
Enhancement versus therapy 
There is no clear distinction between genetic enhancement and gene therapy. However, whether a genetic modification procedure is deemed to be one of enhancement or therapy could affect its degree of accessibility, as therapeutic procedures are more likely to be covered by insurance.
One approach to distinguishing between the two is to classify any improvement beyond that which is “natural” as an enhancement. “Enhancement” would then include preventive measures such as vaccines, which strengthen one’s immune system to a point beyond that which would be achieved “naturally.”
Another approach is to consider therapy as encompassing any process aimed at preserving or restoring “normal” functions, while anything that improves a function beyond that which is “normal” would be considered an enhancement. This, however, would require “normal” to be defined, which only frustrates the clarification of enhancement versus therapy.
Yet another way to distinguish between therapy and enhancement might rely on the goal of the genetic alteration. But the classification of the goal will necessarily depend on how “disease” or “normal” is defined.
Genetic enhancement in humans 
If genetic enhancement is defined such that it includes drugs that are made with genetic knowledge or using rDNA techniques, then forms of genetic enhancement are already in use. Parents seek human growth hormone for their healthy, non-growth hormone deficient short children in hopes of improving the children’s self-esteem. Some athletes use erythropoietin, a hormone that regulates red blood cell production, in efforts to improve their performance.
Using the results of genetic tests to make reproductive decisions based on non-disease traits could be considered to be a form of passive genetic enhancement. Those seeking to create an “enhanced” child could simply turn down potential mates who do not exhibit the desired advantages. Likewise, selectively aborting fetuses after performing an in utero test could be categorized as a type of enhancement technique.
Gene transfer experiments in animals have so far failed to produce results that would justify performing gene transfer in humans; however, gene transfer techniques may eventually be used for enhancement purposes. Gene transfer can be used to modify either somatic or germ-line cells Gene transfer approaches involving the early embryo are presently far more effective than somatic cell gene therapy methodologies, which may result in “random integration of donor DNA, a lack of control of the number of gene copies inserted, significant rearrangements of host genetic material, and a five to ten percent frequency of insertional mutagenesis.” In general, however, the use of gene transfer techniques to modify a phenotypic trait will probably be unsuccessful. Hundreds of genes may play a role in any expressed phenotype; and gene transfer attempts to modify only specific loci in isolation.
Somatic gene transfer will not result in a heritable genetic modification. Germ-line gene transfer, on the other hand, will produce transmittable genomic changes.
Concerns regarding genetic enhancement 
A number of concerns are raised by genetic enhancement. The concerns are based on ideas of equality and fairness, as well as philosophical and religious arguments.
The Undermining of the Principle of Social Equality 
An issue that arises in the context of genetic enhancement is the provision of equal access to genetic enhancement technologies. The high cost of genetic enhancement could prevent all but the wealthy from gaining access to enhancement procedures. Wealth-based genetic enhancement could create a social hierarchy, with those who can afford enhancement gaining power over the unenhanced. If individuals are enhanced by the use of germ line modifications, then the enhancements will be passed on to offspring, who would then pass the enhanced genes to their offspring, and so on. This would create a division between those who are enhanced and those who are not. To the extent that the enhancements made individuals more successful, enhanced individuals would be expected to gain power over those who cannot afford enhancement procedures.
The creation of an unfair advantage 
Distributive justice notions issues would arise, as the net effect of genetic enhancement procedures felt by those who could afford such procedures would probably be less than the benefit that would be perceived by those who cannot afford genetic enhancement procedures. The costs associated with the procedures would make it difficult to provide access to those who are naturally the least advantaged.
Evolutionary concerns 
There is some concern that genetic enhancement could affect human evolution. In response, geneticists have pointed out that human evolution will probably be unaffected, because evolution results from a nonrandom change in allelic frequencies due to selective pressure. Individuals with certain patterns of alleles are favored reproductively, so any introduction of new alleles by gene transfer would have a negligible effect on the species.
Additionally, it is not clear that the phenotypes of genetically enhanced individuals would be those that lend themselves to greater reproductive success.
Furthermore, any genetic modification that does not affect germ cells will not be transmitted to offspring. On a related note, regardless of whether the enhanced genes themselves are actually passed on, evolution in memes may occur if genetic modification of parents improved the unmodified offspring's fitness and propagated the behavioral tendency to genetic enhancement.
Philosophical or religious objections 
Some critics have raised arguments against genetic enhancement based on the idea that humans engaging in genetic enhancement would be overstepping their bounds by “playing God” and intervening in fundamental biological processes.
Genetic enhancement procedures may result in a reduction in the general feeling of social solidarity or goodwill. Assuming that people recognize that their talents that contributed to their successes are due to a “gift” of good genes rather than hard work, they may feel obligated to share the rewards of their genetic gifts with those less fortunate. People may be less likely to share the benefits of their genetic advantages, however, if they no longer attribute their talents and successes to good fortune. On the other hand, the behaviors of genetically enhanced humans may be unpredictable. Individuals may even become misanthropic due to the feeling that they are mutants that were created in a test tube.
Regulating access to genetic enhancement 
In general, most countries do not regulate the ability of those who are naturally talented to further enhance certain characteristics. People who naturally excel at sports, for example, are not prohibited from training and further improving their athletic abilities; and children with above average capacities for learning are routinely placed in honors or accelerated academic programs. Perhaps because such inequalities are perceived as being the result of innate talents or abilities, we are willing to tolerate these differences.
Genetic enhancement is considered morally contentious, however, and access to enhancement procedures will probably be regulated. Possible regulatory schemes include a complete ban of genetic enhancement, provision of genetic enhancement procedures to everyone, or a system of professional self-regulation.
Banning all genetic enhancement procedures would keep wealthy people from using genetic enhancements to gain power over unenhanced individuals; however, preventing individuals from illegally obtaining genetic enhancements may be difficult. Preventing people from engaging activities that they would otherwise pursue would also raise issues of fairness.
Making genetic enhancement procedures available to everyone might be the most fair, but it could also be extremely costly; and some individuals would inevitably choose not to undergo enhancement procedures. Hence, this regulatory scheme could result in the same classes of enhanced and unenhanced individuals that would be expected if there were no regulation.
Perhaps the most practical regulatory approach is the self-regulation of health professionals. The American Medical Association’s Council on Ethical and Judicial Affairs has stated that “genetic interventions to enhance traits should be considered permissible only in severely restricted situations: (1) clear and meaningful benefits to the fetus or child; (2) no trade-off with other characteristics or traits; and (3) equal access to the genetic technology, irrespective of income or other socioeconomic characteristics.”
- See http://www.genome.gov/10004767
- See http://www.genome.gov/10004767
- AMA Council on Ethical and Judicial Affairs, Report on Ethical Issues Related to Prenatal Genetic Tests, 3 Archives Fam. Med. 633, 637-39 (1994), available at http://archfami.ama-assn.org/cgi/reprint/3/7/633