Using Genetic Testing: A Guide for Non-Geneticists BY SUSAN E . HAHN , M S, C GC
In the past, the ability to understand genetic influence on health was limited by technology. This situation changed with the completion of the human genome project in 2003 and the onset of next-generation sequencing (NGS), which enabled sequencing of DNA at unprecedented speeds and sharply lower costs. Now, more than 500 laboratories offer tests for more than 20,000 conditions. The Genetic Test Registry reports that there are nearly 75,000 tests available,1 while a database compiled by the technology company Concert Genetics records more than 165,000 tests.2 Most are laboratory-developed tests that are not subject to FDA oversight, although they are subject to regulations under the federal Clinical Laboratory Improvement Amendments of 1988 (CLIA) law. With only approximately 25,000 genes in the human genome, the substantial number of available tests can be attributed to differences in methods, sample type, variant assessment, and/or genes included in multigene assays. Approximately 3.5% to 5.9% of individuals have a genetic variant associated with significant health implications.3 Beyond diagnosis and risk assessment, genetic and molecular testing are used to evaluate drug response (pharmacogenetics); inform prognosis and treatment of solid tumors that result from acquired, or somatic, mutations that occur in cells; direct organ transplant decisions and management; and test for infection. Although genetic testing is costly, it is highly effective when used appropriately. For example, quickly diagnosing babies with spinal muscular atrophy is paramount to avoid irrevocable damage that begins at birth. Asymptomatic patients with hereditary cancer syndromes such as Lynch or hereditary breast and ovarian cancer syndrome should receive enhanced and earlier cancer surveillance, chemoprevention, and/or prophylactic surgery. In some instances, a genetic diagnosis ends the diagnostic odyssey, thus reducing unnecessary, costly, and time-consuming evaluations and procedures.4 Knowledge of a specific gene or variant may also provide opportunities for families to connect to a support network, participate in research, enable family planning, and inform personal decisions. This rapidly evolving and complex testing landscape can pose a challenge for non-genetics professionals looking to deliver value-based care. Many are not trained to assess genetic risk, order genetic tests, or interpret results. They also may be unfamiliar with referring patients to genetics professionals. Consequently, genetic testing is both overused (20.6%) and underused (44.8%).5 While overutilization is an economic and quality concern, underutilization is concerning from a health outcomes perspective. There are three ways that non-geneticists can ensure they are appropriately and efficiently using genetic testing:
32 l JOURNAL OF AMERICA’S PHYSICIAN GROUPS
Fall 2022
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The rapidly evolving and complex testing landscape can pose a challenge for non-genetics professionals looking to deliver value-based care.”
