his report apply to all emerging areas in public health, including genetics.
The Interface of Genetics and Public Health
In recent years, a new hybrid subspecialty of genetics and public health has emerged. Public health genetics (a term mostly used in the United States [13-14]) has been defined as the application of advances in genetics and molecular biotechnology to improving public health and preventing disease (14). Community genetics (a term mostly used in Europe ) has been defined as "a branch of genetics that has service and science components." The service component seeks to integrate genetic services into community interventions. The science component encompasses the research needed to develop and evaluate services (15). Public health genetics and community genetics could be viewed as one and the same. Nevertheless, as we think about the broader mission of public health, namely "to fulfill society's interest in assuring conditions in which people can be healthy" (12), there will be unavoidable integration of new genetic information into all public health programs and across all diseases, whether or not the diseases are labeled "genetic diseases.", or the services called "genetic services". All public health professionals, therefore, will need an increasing appreciation for integrating genetic research, policy and program development into their daily work. This is not different from the expected integration of genetics into health care in general and across the various medical subspecialties (16-17). While recognizing the need for a cadre of public health researchers and practitioners fully trained in genetics, we also believe that all public health professionals will be using advances in human genetics in research and practice. We do not particularly endorse the creation of a new public health subspecialty in genetics; rather, we encourage and emphasize the smooth integration of genetics into public health practice. Some of the distinctions between these views are shown in Table 2. Nevertheless, the reader will see various terminologies and definitions used by contributing authors to address the interface between genetics and public health.
One may wonder what is the meaning of prevention in the context of genetics and public health? Juengst (19) used the terms "genotypic prevention"-the interruption of genetic trait transmission from one generation to the next through reproductive counseling, carrier testing, prenatal diagnosis and pregnancy termination-and "phenotypic prevention"-the prevention of disease and death among people with specific genotypes (19). In its strategic plan (11), CDC clearly endorses the concept of phenotypic prevention as the strategy for public health-driven programs. Phenotypic prevention can be achieved by interrupting harmful interaction of environmental cofactors with human genetic variation or by using gene therapy to correct deficiencies in gene products.
Although public health-driven prevention may be clear-cut for adult-onset multifactorial conditions such as cancer and heart disease, its role is more problematic for early-onset, lethal single-gene conditions such as Tay Sachs disease and other severe conditions affecting children. It has been argued that an important role still exists for public health activities in prenatal diagnosis and genotypic prevention of severe or lethal conditions (20). Assurance of individuals' and couples' access to reproductive risk information could improve their own well-being, a goal that could be encompassed within a broad definition of health. For many couples, the availability of prenatal diagnosis provides a level of reassurance that permits them to proceed with childbearing they would otherwise forego. Assuring the availability and voluntary access to prenatal services and evaluating the impact of these services would fall within the purview of public health practice; nevertheless, while the public heath community should take an active role in promoting the use of genetic tests and services when there are proven and cost-effective interventi