Revolutionary, unprecedented, unsurpassed—These adjectives are being used to describe the Human Genome Project’s potential to benefit society. The understanding of the human genome that has been gained is almost certain to lead to breakthroughs in medicine that may ultimately eradicate many of today’s diseases.
The previous two articles about the human genome in Food Insight [“Genomics 101: An Introduction to the Human Genome” (May/June 2001) and “The Human Genome: A Master Code for Better Health” (July/August 2001)] covered the potential benefits of the human genome, including:
- Opportunities for the discovery of keys to individuals’ genetic susceptibility to disease,
- Possibilities for the development of functional foods and drugs uniquely tailored to help manage that susceptibility, and
- Development of individualized dietary counseling and/or medical monitoring to provide support to those with a genetic predisposition to certain conditions.
This dynamic new technology also poses questions about safety, human rights issues, and moral implications, however. Finding the answers to questions like these may be as just as important (and just as complex) as making the technical discoveries that prompted them.
The Potential of Genetic Screening
As the cost of genetic testing decreases, it may become possible to screen groups of people for any genetically linked trait. This expanding capability will force some very tough decisions. For example, women with a mutation in either of the genes known as BRAC1 or BRAC2 are at a very high risk of developing breast cancer and ovarian cancer. A DNA test is available to identify carriers of this mutation, but the decision whether to undergo this test has profound implications.
Why Undergo Genetic Screening?
Currently, the only sure way to prevent breast cancer is prophylactic mastectomy, but conscientious use of self-examinations and regular mammograms can detect the disease at an early stage when treatment is very effective. On the other hand, ovarian cancer is far more difficult to detect, and the option of a prophylactic ovariectomy may be acceptable to some high-risk women—especially those beyond reproductive age. Another factor affecting this decision is that our understanding of cancer and other degenerative diseases is rapidly increasing, and so the discovery of an outright cure during the next few decades is a very real possibility. The decision to undergo genetic screening is therefore a very difficult one to make, but an informed choice involving consultation with family and health care professionals is the best solution.
One advantage of genetic screening could be to help an individual make informed decisions about, for example, becoming a parent; planning a career; choosing investments; or deciding about insurance coverage, travel, or education. The knowledge that one is predisposed to cancer, however, could have negative effects in countless other areas including mood, self-confidence, ambition, and setting future goals. Also, what if others learn of this information? Will a high-risk person be treated differently by her or his spouse, employer, or insurance company?
To date, there is little evidence that insurance companies or employers discriminate against individuals on the basis of genetic makeup or the results of genetic screening tests. Insurance executives have defended the industry by noting that the cost of widespread genetic screening may be prohibitive, that most people are insured as part of a group so the cost to treat any one individual is relatively trivial, and that companies don’t want to risk damage to their image by being accused of genetic discrimination.
For example, public pressure was a critical factor in a recent incident involving a major railway company. The company had initiated genetic testing for some of its employees to determine susceptibility to carpal tunnel syndrome, but the company quickly discontinued the testing when the media reported that it was being done. Despite the protection offered by public pressure—as well as federal legislation, which has been passed and implemented—concerns about possible discrimination on the basis of one’s genes are likely to persist.
Modifying the Human Gene Pool in Theory and in Practice
As our ability to screen for genetic characteristics increases, it will be possible to alter the human gene pool by selectively determining which pregnancies are carried to term. Theoretically, this technique could be used to identify “undesirable” genes in an effort to reduce their frequency and gradually improve the human genome.
The central questions regarding this practice relate to the contentious issue of reproductive rights. Inherent in the decision to genetically screen an embryo may be the willingness to terminate the pregnancy if a defect is found. The appropriate criteria (if any) on which this decision is based are grounded in the value systems of the parties involved. But where will the line be drawn? The answer requires the formidable task of finding an acceptable balance between moral and ethical fundamentals on the one hand, and individual freedoms on the other.
Moral Concerns and Future Research
At the earliest stage of development, all cells in an embryo have the capability to develop into any tissue in the body. Animal experiments with such cells (and early studies with humans) have shown that they have great promise for the treatment of Parkinson’s disease, juvenile-onset diabetes, and possibly many other diseases including cancer and heart disease. Scientists are eager to extend this work to studies with humans, but the ethical issues have become a major consideration.
Other highly controversial areas of genetic research include inserting human genes into animal organs in an effort to make them suitable for transplantation into people, and cloning. The major medical advances that will arise from the use of these techniques have the undeniable potential to extend human life expectancy, but the debate on this enormously complex topic is far from over and science will continue to evaluate these areas of genetic research.
Legal Considerations—“My Genes Made Me Do It!”
DNA testing is now routinely used to help solve crimes, but the impact of genetics on the judicial system will be far more complicated. Data from the Human Genome Project suggest that certain mental conditions and behavior patterns are linked to specific genes. For example, scientists suspect that a defective gene on human chromosome 6 predisposes individuals to schizophrenia, and deviant behavior may also be genetically influenced. If this hypothesis is confirmed, should affected persons convicted of a crime be punished even though their actions were genetically preprogrammed? If negative behaviors are linked to genes, should individuals be screened for such genes at birth? What measures (if any) are appropriate to prevent such individuals from committing the crimes to which they are predisposed? The debate on such complex issues is only beginning to unfold, but rapidly evolving technology will soon demand answers.
Where Do We Go from Here?
After 10 years, scientists have nearly completed sequencing the 3 billion base pairs of the human genome. Given the societal implications, that may have been the easy part. The world now stands on the threshold of a new age in biology that promises both enormous hopes and enormous concerns. Clearly, there is no going back—the potential benefits and the quest for knowledge are too compelling. Logic suggests that the stakes of this new game are too high to permit our zeal for technical advancement to short-circuit our ability to control it. Humanity has historically thrived on emerging technologies, and human genomics provides another opportunity to apply our accumulated wisdom as we judiciously meet the exciting but daunting challenges of the future.
