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human gene discoveries continue, the usefulness of the resulting
information in the practice |
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medicine remains in question. In the July 13, 2000, issue of the
New
England Journal of Medicine, Drs. Neil Holtzman
and Teresa Marteau, answer mostly no to the question
“Will genetics revolutionize medicine?”
They argued that genetic information is useful only in
extremely rare disorders, where the disease is the inevitable
outcome of having the genetic variant.
They also argued that
genetics has limited value in predicting, preventing, or
treating common diseases such as cancer, diabetes, and other
diseases with multifactorial causation. Based not only on 10
years of human genome research but also on the impact of
genetics on the practice of medicine today, Holtzman and Marteau
predict that genetics is unlikely to revolutionize medicine.
Their views, however, stand in contrast to the opinions of many
others, including Dr. Francis Collins, Director of the Human
Genome Project, who in the “Shattuck
Lecture: Medical and Societal Consequences of the Human Genome
Project,” predicts
sweeping changes in medicine as early as the year 2010 when
individuals conceivably will be able to accurately assess risk
for common diseases and determine appropriate intervention
strategies based on a personal genetic profile.
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The
Public Health Perspective
Let
us examine, from a public health perspective, the continuum of opinions
on the impact of the human genome project on the practice of medicine.
Holtzman and Marteau paint an accurate picture of the impact of
genetics on medicine both today and in the immediate future. They point
out many of the issues that limit widespread applications of
genetics—the incomplete penetrance of genotypes for common diseases,
the limited ability to tailor treatment or prevention to genotypes, the
low magnitude of risks conferred by various genotypes for the population
at large, and some of the many social issues involved in genetic
testing.
The other end of
the spectrum represents the possibilities, perhaps even the goals, for
future use of genetic information. Considering the rapid advances in
technology in recent years and the continuation of gene discoveries, the
possibilities for new methods of detection and prevention are endless.
In fact, because most common diseases result from the interaction among
several genes and environmental factors (such as diet, drugs, and
infectious agents), the same arguments that Holtzman and Marteau raised
can be used to show how interacting factors, once discovered, will
increase the penetrance of genotypes at single genes and target medical
and behavioral interventions, as discussed in the letters
to the editor.
Planning
for the Future
Nevertheless,
careful planning and additional research are needed before we see a new
era in medicine. Medical
and public health researchers must continue population-based research
studies to increase our understanding of genetic variation and the risk
for disease, to determine other associated risk factors and their role
in the development of disease, and to address the associated social
issues. Throughout this
process, two challenges will face public health agencies.
Challenges
Facing Public Health
The first
challenge will be to ensure that validated genetic information is used
safely and effectively to prevent disease and improve health, especially
in underserved populations. The second challenge will be to protect the
public from premature and inappropriate use of genetic information by
developing and disseminating timely and ongoing information about the
laboratory and clinical performance of genetic tests and their utility
in improving health and preventing disease.
Only after researchers
complete clinical and epidemiologic studies on thousands of genes and
interacting factors will we have the types of data needed to translate
gene discoveries into medical practice in the 21st century.
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