From Genetic Counseling in Individuals to Cascade Screening in Populations: An Emerging Role for Public Health Practice
November 29th, 2012 12:37 pm ET - Muin J Khoury, Director, Office of Public Health Genomics, Centers for Disease Control and Prevention
There are more than 2500 diseases for which genetic testing is currently available
. Most of these diseases are individually rare conditions but collectively affectmillions of individuals and families
worldwide. Genetic diseases are usually caused by mutations in one or a few genes that may confer a high risk of illness, disability and early death. Immediate relatives of affected people can be at highest risk for these diseases. Rapid advances in genomics, including whole genome sequencing
, are leading to more accurate diagnosis, early detection and carrier testing for these diseases. Genetic counseling
provides information for decision making by affected people and their families.
Cascade screening is an active process to find relatives of persons affected with certain genetic conditions, for which interventions exist that that can save lives. In the recent video, “Cascade genetic screening and public health practice: an idea whose time has come”
, the case was made that 2 million people in the United States are affected with one of the three genetic conditions mentioned above. Existing public health programs at the federal and state levels (notably cancer and heart disease programs) can partner with clinical medicine and other stakeholders to develop policy, educational and surveillance-based interventions for these conditions. Since 2011, public health programs in hereditary breast and ovarian cancer have been under way in Michigan, Oregon and Georgia.
What about the role of public health for the vast majority of other genetic conditions, where cascade screening is not a tier 1 application? For many individual rare disorders, there may never be sufficient evidence to meet the highest evidentiary criteria of major guideline-producing organizations using traditional evaluation methods. Clearly, unbiased, accessible information about genetic conditions is important for affected individuals and their relatives. For example, CDC has developed and sponsored educational and informational programs around selected genetic conditions, such as Duchenne Muscular Dystrophy, Fragile X Syndrome, and Primary Immune Deficiency Disorders
. Many community programs exist both within and outside the US, a field sometimes referred as Community Genetics
. Information could be collected through the use of population based registries that could show impact of these programs at the individual, family and population levels.
We will continue to monitor the evolving scientific evidence to include more genetic conditions in tier 1 applications for population and/or family-based cascade screening programs. We invite our readers’ comments and input on what public health practice can do for individuals and families affected with genetic diseases.
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