Genetic Testing and Common Disorders in a Public Health Framework: How to Assess Relevance and Possibilities

By: Hailey Gosnell | December 04 2012 3:03PM

When it comes to disease, what is the cost of knowledge? The field of genetics has progressed to the point that scientists are able to test for molecular biomarkers related to common diseases that plague mankind. Such a capability opens doors to a wealth of information about how our genome functions with relation to illness and the extent to which the environment plays a role. However, it is hard to determine when we have crossed the fine line between gathering helpful information and progressing toward diminishing returns.

Recently, the attention of genetic research has moved from studying simple Mendelian diseases (diseases that follow a pattern of direct genetic inheritance) towards comprehending complex disorders such as cancer and Alzheimer’s. These common complex diseases are disorders that fail to fit the neat mold of Mendelian genetics. They can be governed by a variable number of genes and/or interactions between them and many environmental factors. Such advancements in research, however, pose challenges in implementation and future progress. Several phases of pivotal research are necessary to ensure safe implementation of products from research findings, including clinical trials, guideline development, and dissemination (spreading of scientific findings). Difficulties with the translation of laboratory research findings to the clinical sector need to be well understood if disease, diagnosis, treatment and prevention of complex diseases can continue.

Approaches from the research sector are reaching macro levels (projects undertaken by larger numbers of scientists) and studies generating hypotheses are replacing those driven by hypotheses. For example, the Human Genome Project was performed in order to generate new questions regarding genetic association to disease susceptibility. Such a change suggests future work will focus on analyzing complex pathways of disease as a whole instead of single genes by incorporating the genomes of other organisms into the study of our own, broadening the horizons of genetic knowledge.

While the research sector as a whole is taking a progressive path to understanding relationships between complex disease formation and genetic markers, clinical geneticists, molecular geneticists, and cytogeneticists (geneticists who study cell function) are still focusing primarily on rare disorders (those more directly related to genetic inheritance). Though the role of genetic specialists in research of complex disorders is much less clear, most deaths and hospital admissions are related to the complex (more common) diseases while few are due to rare disorders. While genetic specialists need to focus more on diseases pertinent to the general population, health-care providers need to become more literate in interpreting genetics. Practicality of genetic testing lies in building bridges between basic research scientists, genetics experts, and health-care workers.

In light of recent developments in genetics research, there is reason to assess the validity and relevance of genetic testing and disease screening from the perspectives of clinical medicine and society. Genetic testing is defined as the analysis of DNA or genetic biomarkers for the assessment of risk factors for a particular disease, usually limited to those who seek professional help. Genetic screening traditionally refers to programs geared towards whole populations of individuals without disease symptoms or subpopulations characteristics of disease.

Essential facets of a genetic assessment’s usefulness in a given situation include: the burden of knowledge of increased risk for disease, epidemiological measures, test accuracy, and comparison with alternate methods of detecting the disorder. Cost-benefit concerns of genetic tests address the uncertainty of characterizing genes involved in complex disorders, slanted knowledge about which groups are at higher risk, the chance that inheritance may result in disease development, and incomplete ability to predict the efficiency and price of intervention.

From a social standpoint, genetic testing can cause unnecessary distress on both a small scale (involving screening in a single patient) and on a larger scale (commercial marketing of tests for genetic disorders) if misleading or misinterpreted. Many people seem to think of genes themselves as harmful instead of considering the fact that only dysfunctional versions of those genes cause disease. Further, genetic markers deemed harmful in the context of one disease may actually be beneficial in the case of another, thus complicating the efficacy—or effectiveness—of genetic testing.

Decisions about genetic test implementation spur from consideration of consequences (both benefits and costs) of alternative medical interventions. Examples of such interventions include relying on lifestyle choice as a definitive factor in well being and treating an illness by symptom observations. Before a final decision is made regarding the use of a genetic test or screening program, tests must be assessed according to performance and effectiveness. Whether or not a genetic test would be deemed reasonable in any case, early identification of disease predisposition shown by genetic biomarkers might help to lessen suffering and early death while reducing medical expenses for disease treatment and therapy.

Not Exactly Rocket Science

Genetic Testing and Common Disorders in a Public Health Framework: How to Assess Relevance and Possibilities