Congress has considered, at various points in time, numerous pieces of legislation that relate to genetic and genomic technology and testing. These include bills addressing genetic discrimination in health insurance and employment; precision and personalized medicine; the patenting of genetic material; the privacy of health information, including genetic information; and the oversight of clinical laboratory tests (in vitro diagnostics), including genetic tests. The focus on these issues signals the importance of public policy issues surrounding the clinical and public health implications of new genetic technology. As genetic technologies proliferate and are increasingly used to guide clinical treatment, these public policy issues are likely to continue to garner attention. Understanding the basic scientific concepts underlying genetics and genetic testing may help facilitate the development of more effective public policy in this area. Considering that virtually all disease has a genetic component, the potential public health impact of genetic disease may be significant. Over time, as translational obstacles are addressed, the value of and role for genetic testing in clinical medicine may increase. As the role of genetics in clinical medicine and public health continues to be better understood, the importance of public policy issues raised by genetic technologies is likely to grow. Limited knowledge of both the appropriate role for genetic information in the clinical management of patients, and the genetic and environmental factors underlying disease, may create a challenging climate for public policymaking. As genetic research continues to advance rapidly, more genetic tests will be developed that provide information with unclear or debated clinical implications as a result of genetic technology outpacing the development of evidence for its application. This situation may create public policy challenges, for example, in terms of decisions about the coverage of genetic testing services and the regulation of such tests. Policymakers may need to balance concerns about privacy and the potential use and misuse of genetic information with the potential of genetics and genetic technology to improve care delivery, for example by personalizing medical care and treatment of disease. In addition, policymakers face decisions about the balance of federal oversight and regulation of genetic tests, patients' safety, and innovation in this area. Finally, the need for and degree of federal support for research to develop a comprehensive evidence base to facilitate the integration of genetic testing into clinical practice (for example, to improve health care outcomes or to support coverage decisions by health insurers) may be debated. Virtually all disease has a genetic component. The term "genetic disease" has traditionally been used to refer to rare monogenic (caused by a single gene) inherited disease, for example, cystic fibrosis. However, research now shows that many common complex human diseases—including common chronic conditions such as cancer, heart disease, and diabetes—are influenced by several genetic and environmental factors. For this reason, they could all be said to be "genetic diseases." For more information about fundamental concepts in genetics—including genes, chromosomes, phenotype, and genotype—see the Appendix . The genetic make-up of an individual's disease—as well as an individual patient's genetic make-up—will help guide clinical decision making. Experts note that "(w)e have recently entered a transition period in which specific genetic knowledge is becoming critical to the delivery of effective health care for everyone." This sentiment is shared, despite the fact that the translation to practice has perhaps been slower than anticipated. This is due, in part, to the frequent lack of a comprehensive evidence base to inform clinical validity and utility determinations for many genomic technologies. Researchers have identified a translational gap between genetic discoveries and application in clinical and public health practice and note that "the pace of implementation of genome-based applications in health care and population health has been slow." The information provided by the Human Genome Project is helping scientists and clinicians to identify common genetic variation that contributes to disease, primarily through genome-wide association studies (GWAS). In addition, efforts are underway to close the translational gap, specifically the 2009 establishment of the National Institutes of Health (NIH)-Centers for Disease Control and Prevention (CDC) collaborative Genomic Applications in Practice and Prevention Network (GAPPNet). Still, evidence is oftentimes lacking, making the assessment of the clinical value of genetic tests challenging. Experts note that the moderate effect of many common genetic variations, uncovered by GWAS, has helped to highlight the multifactorial nature of complex disease, and that research efforts will be required to detect "missing" genetic influences. GWAS efforts have identified 1,100 well-validated genetic risk factors for common disease; however, the potential for many of these factors to serve as drug targets is unknown. Research conducted using large population databases that collect health, genetic, and environmental information about entire populations will likely provide more information about the genetic and environmental underpinnings of common disease. Many countries have established such databases, including Iceland, the United Kingdom, and Estonia. No similar effort has yet been undertaken in the United States. However, researchers hope to combine genetic, environmental, clinical, behavioral, and other data to facilitate precision medicine. Precision medicine is the idea of providing health care to individuals based on specific patient and disease characteristics, and is a priority in the President's FY2016 budget. The President's budget request proposes the development of a national research cohort, composed of 1 million or more volunteers, whose health, genetic, environmental, and other data would be collected and used in research studies to identify novel therapeutics and prevention strategies. In many cases, the results of genetic testing may be used to guide clinical management of patients, and a particularly prominent role is anticipated in the realm of preventive medicine. For example, more frequent screening may be recommended for individuals at increased risk of certain diseases by virtue of their genetic make-up, such as colorectal and breast cancer. In some cases, preventive surgery may even be indicated. Decisions about courses of treatment and dosing may also be guided by genetic testing, as might reproductive decisions (both clinical and personal). However, many diseases with an identified molecular cause do not have any treatment available; specifically, therapies exist only for approximately 200 of the more than 4,000 conditions with a known molecular cause. In these cases, the benefits of genetic testing lie largely in the information testing provides an individual about his or her risk of future disease or current disease status. The value of genetic information in these cases is personal to individuals, who may choose to utilize this information to help guide medical and other life decisions for themselves and their families. The information can affect decisions about reproduction; the types or amount of health, life, or disability insurance to purchase; or career and education choices. Currently, there is no single definition for "genetic test," and the scientific community has not reached a consensus about the best definition. However, one way that a genetic test may be defined scientifically is as follows: [A]n analysis performed on human DNA, RNA, genes, and/or chromosomes to detect heritable or acquired genotypes, mutations, phenotypes, or karyotypes that cause or are likely to cause a specific disease or condition. A genetic test also is the analysis of human proteins and certain metabolites, which are predominantly used to detect heritable or acquired genotypes, mutations, or phenotypes. Once the sequence of a gene is known, looking for specific changes is relatively straightforward using modern techniques of molecular biology. Using microarray technology, hundreds or thousands of genetic variations can be detected simultaneously. In addition, new advances in sequencing technology, termed next generation sequencing, have allowed for the rapid sequencing of large portions of DNA, including whole genomes or subsets of genes of interest. The way genetic test is defined can be important to the development of genetics-related public policy. For example, the above scientific definition is broad, including both predictive and diagnostic tests and analyses on a broad range of material (nucleic acid, protein, and metabolites), but this may not be the best way to achieve certain policy goals. It may sometimes be desirable to limit the definition only to predictive, and not diagnostic, genetic testing because predictive tests may raise public policy concerns that diagnostic tests do not (see " What Type of Information Can Genetic Tests Provide? "). On the other hand, policymakers wishing to avoid raising potentially controversial issues associated with predictive genetic testing may instead choose a definition limited to diagnostic testing. In still other cases, it may be desirable to limit the definition to only analysis of specific material, such as DNA, RNA, and chromosomes, but not metabolites or proteins, for example, to help avoid capturing certain types of tests, such as some newborn screening tests, in the scope of a proposed law. Policies extending protection against discrimination—for example, the Genetic Information Nondiscrimination Act (GINA, P.L. 110-233 )—may aim to be broader (e.g., including predictive tests, not limiting the definition to tests analyzing only certain materials). On the other hand, policies addressing the stringency of oversight of clinical laboratory or in vitro diagnostic tests, of which genetic tests are a subset, may aim to be more limited (e.g., only those tests that are considered to be higher risk). In certain cases, the lack of an accepted definition for "genetic test" may affect policymaking. For example, in discussions about whether to add a genetic testing specialty under the Clinical Laboratory Improvement Amendments of 1988 (CLIA, P.L. 100-578 ), the law regulating clinical laboratories, it was decided not to do so, partially based on the fact that there is "no widely accepted definition of a 'genetic test.'" Most clinical genetic tests are for rare disorders, but increasingly, tests are becoming available to determine susceptibility to common, complex diseases and to predict response to medication. With respect to health-related tests (i.e., excluding tests used for paternity, forensic purposes, such as "DNA fingerprinting," or for ancestry), there are two general types of genetic testing: (1) diagnostic and (2) predictive. Diagnostic genetic tests can be utilized to identify the presence or absence of a disease.