Part I GENETICS AND PUBLIC HEALTH: AN OVERVIEW Chapter 1
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Genetics and Public Health in the 21st Century
Genetics and Public Health: A Framework for the Integration of Human Genetics into Public Health Practice
Muin J. Khoury1, Wylie Burke2, Elizabeth Thomson3
1Office of Genomics and Disease Prevention, Centers for Disease Control and Prevention, 4770 Buford Hwy, MS K28, Atlanta, GA 30341
2Department of Medicine, University of Washington, Seattle, WA 98105
3 Ethical, Legal, and Social Implications Research Program, National Human Genome Research Institute, Bethesda, MD 20892
Portions of this chapter are based on the Centers for Disease Control and Prevention's "Translating Advances in Human Genetics into Public Health Action: A Strategic Plan" (1997) (11).
As we enter the 21st century, health care is undergoing phenomenal changes driven, in part, by the Human Genome Project and accompanying advances in human genetics (1). All of the 50,000 to 100,000 human genes will be identified in the next few years (2). As of 1999, more than 10,000 genes have been discovered and catalogued (3). Tests for more than 600 gene variants are already available in medical practice (4). Gene variants found thus far include not only those associated with rare diseases, but those that increase susceptibility to common chronic diseases, such as cancer and heart disease (5).
(Table 1). Risks for almost all human diseases result from the interactions between inherited gene variants and environmental factors, including chemical, physical, and infectious agents and behavioral or nutritional factors, raising the possibility of targeting disease prevention and health promotion efforts to individuals at high risk because of their genetic makeup (6).
Need for Public Health Leadership in Genetics
How to use knowledge from genetics research to promote health and prevent disease-the fundamental mission of public health-is now being explored. However, population-based information is lacking about the distribution of genotypes in different populations, the benefits and risks of genetic testing, and the efficacy of early interventions. Moreover, the complex issues that have emerged (e.g., rapid commercialization of genetic tests, quality of laboratory testing, availability of and access to interventions, and potential discrimination against and stigmatization of individuals and groups) call for public health leadership.
Almost daily, gene discoveries are reported for a wide variety of human diseases (7). Unfortunately, what happens after a new gene discovery is announced is often a haphazard mixture of scientific excitement, heightened public awareness and commercial interest in developing and marketing genetic tests. This problem is exemplified by the events following the 1997 publication of an association between familial colorectal cancer in Ashkhenazi Jews and the presence of a common genetic variant in the adenomatosis polyposis coli (APC) gene (8). One example of the accompanying news coverage, a 1998 article "Genetic Defect Doubles Colon Cancer Risk"(9), stated the following:
"Researchers have found a new genetic defect present in one of every 17 American Jews that doubles a person's colon cancer risk. This mutation is now the most common cancer-associated gene defect identified in any ethnic population. Rarely present in non-Jews, the mutation appears to be responsible for about one in four cases of inherited colon cancer in Askhenazi Jews-those of Eastern European ancestry who constitute more than 95 percent of America's six million Jewish people. The good news is that scientists have developed a blood test, available for $200, that can detect this genetic defect. The test is advisable for everyone in the Ashkhenazim population, whether they have a family history of colon cancer or not."
Although this study needed further confirmation, and its implications for medical practice remain far from clear, the