Genetic testing is used for screening and diagnostic purposes. Genetic tests analyze genes, changes in the function or structure of key proteins coded for by specific genes, or levels of RNA that are involved in certain conditions (CDC). Genetic tests have been developed for over 2,200 diseases (both rare and common).
Genetic screening is performed at a population level in asymptomatic individuals to identify individuals who may be at higher risk for disease. Genetic screening may lead to specific diagnostic tests for a particular disorder. Examples of genetic screening include:
- Family history
- Prenatal screening tests
- Newborn screening tests
- Cancer screening conducted as part of routine prevention and health maintenance visits
Uses of Genetic Tests
There is no single genetic test that identifies all genetic diseases. Reasons to consider genetic testing include:
- Diagnostic Testing
- Predictive Testing
- Carrier Testing
- Prenatal Testing
- Preimplantation Testing
- Newborn Screening
- Pharmacogenomic Testing
Where can I learn about the evidence behind genetic tests?
Scientific evidence and evidence-based recommendations are variable for the many available genomic tests and applications. The Centers for Disease Control and Prevention (CDC) has developed a list of genomic tests and applications in clinical practice, according to three levels of evidence, stratified into three tiers.
- Tier 1 genomic and family health history applications are recommended for clinical use by evidence-based panels based on a systematic review of analytic validity, clinical validity and utility for specific clinical scenarios.
- Tier 2 applications have evidence establishing validity and promising utility, and may be useful for informed decision making, but lack evidence-based recommendations for their use.
- Tier 3 applications have inadequate evidence of validity and/or utility, or have evidence-based recommendations against their use.
The National Human Genome Research Institute provides answers to frequently asked questions about genetic testing here.
A Tiered Approach to Integrating Genomic Tests Into Your Practice
This new CDC video commentary for Medscape is presented by Scott Bowen, MPH, Deputy Director of the Office of Public Health Genomics at the CDC.
Is there a clearinghouse for genetic testing information?
The Genetic Testing Registry (GTR) provides a central location for voluntary submission of genetic test information by providers. Information is provided on the test's purpose, methodology, validity, evidence of the test's usefulness, and laboratory contacts and credentials.
This system is hosted and funded by the National Institutes of Health (NIH) and sponsored and updated in partnership with the University of Washington. The overarching goal of the GTR is to advance the public health and research into the genetic basis of health and disease.
GeneTests is another resource for physicians, health care providers, and researchers that contains a directory of labs and clinics, along with peer-reviewed disease descriptions, and other educational materials intended to help healthcare providers understand the appropriate use of genetic counseling and testing. This resource is hosted and publically funded by the National Institutes of Health (NIH) and sponsored and updated in partnership with the University of Washington.
Newborn Screening Clearinghouse
Baby's First Test houses the nation's newborn screening clearinghouse. The clearinghouse provides current educational and family support and services information, materials, and resources about newborn screening at the local, state, and national levels and serves as the Clearinghouse for newborn screening information. This resource is dedicated to educating parents, family members, health professionals, industry representatives, and other members of the public about the newborn screening system. This site also provides many ways for people to connect and share their viewpoints and questions about the newborn screening system.
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