Risks and benefits of population-based genetic testing for Mendelian subsets of common diseases were examined using the example of colorectal cancer risk

Abstract

Objective: Genetic testing for adult-onset, common diseases is becoming more commonplace in clinical medicine. We modeled the proportions of hypothetic populations that would potentially benefit or suffer harm from widespread predisposition testing.

Methods: Using the traditional two-by-two table from the discipline of epidemiology, we modeled three hypothetic populations using the example of genetic testing for hereditary colorectal cancer in three groups: the general population, a genetically increased-risk population, and a population at increased risk due to nongenetic factors.

Results: We demonstrate that the potential benefits are increased and risks are reduced when testing is limited to those at increased genetic risk when compared with testing in the general population. Where disease incidence is increased due to nongenetic factors, genetic testing has the potential to detract from the detection and reduction of other potentially important risk factors.

Conclusion: While targeted testing can benefit those truly at increased risk, broadly applied genetic testing can do more harm than good.