DNA Testing for Health Risks
The benefits of DNA testing far exceed the scope of criminal justice and contentious paternity cases. From pre- and neonatal care to cancer screenings, accurate DNA testing provides doctors and medical specialists with vital genetic information that contributes to correct diagnosis and proper treatment. It can also play an important role in preventive care. If you're relying on direct-to-consumer DNA tests to assess health risks, be aware of the issues surrounding this proliferating market.
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Background
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The most advanced and sophisticated types of gene testing involve examination of the DNA (deoxyribonucleic acid) molecule--every gene's chemical database. The earliest population-wide genetic tests were performed on newborns in the 1960s and involved screening for the metabolic disorder phenylketonuria (PKU). Detection of this disease at birth allowed for early treatment. In most cases, mental retardation (a condition resulting from PKU) was avoidable. Testing of newborns, coupled with educational campaigns, can even result in eliminating some diseases associated with certain ethnic groups.
Predictive Gene Testing
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Gene testing primarily involves scientists and specialists examining genes for mutations in gene sequences that indicate the presence of or susceptibility to disease. Predictive gene testing ascertains whether an individual with a family history of a genetically transmitted disease may succumb to the disease and/or be a carrier. For example, the predictive gene test for Huntington's disease--a disorder manifesting around age 40 that causes behavioral and cognitive changes, and uncontrollable muscle movement--is performed only on patients who have a demonstrated family history of the disease. Predictive gene testing can have pinpoint accuracy. It can help determine the age of occurrence, and the type and severity of symptoms.
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DTC Gene Testing
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Direct-to-consumer ("DTC") gene tests are currently marketed toward consumers who do not necessarily exhibit symptoms, but may have a family history of an adult-onset condition. The most popular DTC gene tests are for Alzheimer's disease and certain cancers. DTC gene tests still require a doctor's order and administration. One example is the BRCA gene test for breast cancer. It examines the tissue's DNA to determine if there are mutations in two breast cancer susceptibility genes (classified as BRCA1 and BRCA 2). Once results are obtained, patients are told if they carry the inherited BRCA gene, and they are given an estimate of their personal risk for breast cancer. Criticisms of these DTC gene tests center on their high cost and the difficulty in interpreting positive results. DNA sequences that may be irregular, but are not necessarily mutations, may or may not be valid predictors of disease.
Genetic Counseling
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The types of genetic tests available can help determine what disorder a patient's symptoms indicate, whether a patient is susceptible to a particular condition (even without exhibiting symptoms), if a parent is a carrier for certain diseases, the genetic traits of the fetus, and the presence of certain conditions in newborns. With the array of genetic tests available, it is wise to seek advice from licensed professionals who can provide direction and insight, including--given the uncertainties surrounding interpretation and the likelihood for error--whether genetic DNA testing is the best option.
Best Results
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Tay-Sachs disease--a condition afflicting the nervous system that results in disability and early childhood death--has virtually disappeared from the Jewish population as a result of gene tests and community education. Current genetic screenings performed routinely on newborns include testing for sickle-cell anemia, especially among the African-American population. Routine genetic screenings performed on pregnant women include tests for Down syndrome and cystic fibrosis. These diseases and conditions have seen a radical reduction in occurrence because of genetic DNA testing.
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