Frequently Asked Questions About Research Using NHANES DNA Samples
What is DNA?
Deoxyribonucleic acid (DNA) is the chemical name for the molecule that carries genetic instructions in all living things. DNA is the central information storage system of most animals and plants. DNA is often compared to a set of blueprints for the human body. The segments of DNA that carry genetic information are called genes. DNA for NHANES is obtained from blood samples. For definitions of terms related to DNA research the Talking Glossaryexternal icon managed by the National Human Genome Research Institute is a useful reference.
Why does NHANES collect and store DNA samples?
With recent advances in technology, NHANES can now collect genetic information from the same blood sample obtained for laboratory testing. The new genetic information is useful to public health scientists because it allows them to test for relationships between diseases and genetics. Also, almost unique to NHANES, scientists can describe the relationship between disease and genetics in the context of exposures, such as exposures to pesticides or second-hand smoke. Continued collection of genetic information by NHANES will ensure that public health scientists have the most comprehensive data available to better understand the important relationships between disease and risk factors.
Where and how are the DNA samples stored?
The NHANES DNA samples are stored at CDC’s National Center for Environmental Health’s laboratories in a sterile, protected environment maintained at a steady 80 degrees. This careful handling of DNA specimens will ensure their long-term availability for future studies.
What have public health scientists studied with NHANES DNA? What have they learned?
Genetic screening – In order for public health professionals to make decisions about whether or not to recommend genetic screening for disorders that are caused by inherited factors, it is essential to know the occurrence in the United States population, that is, how many people carry the gene for a specific condition. One study using NHANES DNA determined the prevalence of Hemochromatosis (excess accumulation of iron in the heart and liver) and evaluated the usefulness of screening for that genetic marker. Other studies have helped determine the advisability of screening for other conditions.
Genetic variation in the U.S. population – It is important to understand how individuals and groups vary in disease susceptibility, progression, and outcomes. For example, the results from one study provided the foundation for a comprehensive databank of human genetic variation in the U.S. that will serve as an important reference for future investigations into the role genes play in disease. It also helps determine the reasons for differences in health among various racial and ethnic groups and how genetic variants might contribute to health disparities.
Pre-disposition to chronic diseases, such as diabetes and chronic kidney disease NHANES DNA studies have identified genetic differences among individuals measured in blood levels of glucose or insulin and other aspects of human physiology important to the causes of type 2 diabetes. Diabetes is one of the most frequent conditions in the U.S. population and one of the fastest growing. The new genes that have been identified give new ways to discover interventions that might be used to prevent or treat type 2 diabetes. Chronic inflammation may play a role in the development of chronic kidney disease. Certain gene variants are associated with chronic inflammation and NHANES DNA research validated that relationship. Other research is investigating the associations of gene variants with outcomes related to asthma, cardiovascular disease, infectious disease, lead exposure, osteoporosis, and reproductive health.
Identification of risk factors – Studies using NHANES DNA have also focused on identifying specific genes which may be associated with various risk factors. With the identification of these genes, there could be important advance notice of the presence of risk factors and thus individuals could be advised to adopt certain health practices or change other behaviors to prevent the onset or the complications of a specific disease or condition. Some of the on-going research has focused on obesity and relevant genetic markers.
For more information on specific projects using NHANES DNA, go to Research Using DNA Samples.