The Implications of Genetic Testing: It’s More Than A Simple Blood Test

July 26, 2011

Virtually half of the articles about genetic testing in the lay press contain the words "simple blood test". In a high-tech medical world of complicated imaging, medications and surgeries, reporters seem intrigued that much genetic testing can be performed on a blood specimen.

Editor’s Note: For medical professionals, the routine of diagnosis is less straightforward for cases in which genetic testing is required. The ramifications of the test results necessitate additional education and counsel for the patient and their family in order to fully prepare those involved, and thereby avoid unnecessary confusion, fear and stress. The following contribution by a genetic counselor who deals daily with patients encountering genetic testing for the first time highlights the complexity of issues surrounding what initially might be viewed as "a simple blood test."

Virtually half of the articles about genetic testing in the lay press contain the words "simple blood test". In a high-tech medical world of complicated imaging, medications and surgeries, reporters seem intrigued that much genetic testing can be performed on a blood specimen. And for doctors and patients, ordering a blood draw or sticking your arm out for a few tubes of blood seems easy.

So why the fuss? Because after the easy blood draw, the laboratory analysis is often complex and expensive, the results can sometimes be difficult to interpret, and the results usually impact more than an individual patient. Regardless of the reason for the blood draw, primary care physicians are the conduit for the information, and should know the implications of the test and counsel accordingly.

The variety of circumstances for which genetic testing is appropriate are numerous. Situations as diverse as a chromosome analysis for a baby with multiple malformations, a newborn's PKU screen, a teen with growth abnormalities and a suspected metabolic problem, and an adult with a family history of colon cancer wanting presymptomatic testing generate a wide spectrum of issues that need to be reviewed prior to ordering the blood test. In addition to the standard disclaimer on consent forms regarding the impact of a blood draw (slight pain, possible bruise, fear of needles), many genetic consent forms contain language about psychological impact, family relationship issues and the social risks of discrimination. These issues vary with the circumstances, but are important to consider for each type of genetic test.

Who is the testing candidate? Many, but not all, genetic tests are ordered for diagnostic purposes as a consequence of clinical findings. In those situations, the person for whom the testing is most useful is the affected one. However, when ordering a test for presymptomatic purposes, the person on whom relevant information will be obtained may not be your patient. In families in which there is a significant amount of cancer, the most appropriate testing candidate may be a parent or a cousin who was diagnosed at a young age. For example, a negative colon cancer DNA result on a young man may not be as useful if he is not in a family in which the specific gene causing the increased colon cancer risk is known. Defining a testing strategy and then being willing to advocate for testing, especially if the best candidate lives in a different community or has a different insurance plan, can be time consuming and vital to obtaining valuable information for your patient.

The impact of making a diagnosis. Not confirming a diagnosis can be frustrating for a family, who may be wanting a better understanding of the etiology, prognosis and potential options for an affected child. Conversely, confirming a diagnosis provides a "label" with valuable information about natural history and treatment options, but can also create potentially negative social stigmatization. Appreciating the impact that either a positive or negative result will have on a patient or family is a key aspect of providing comprehensive care.

Genetic ramifications. In addition, test results will often have genetic (and sometimes medical) ramifications for other family members. Parents may be identified as obligate carriers of an autosomal recessive gene, siblings may be at risk for developing a particular condition, a parent may be the source of an inherited dominant mutation, extended family members may now be at risk of inheriting mutations. In addition, a new medico-legal twist of informing these extended family members who may be at risk as a result of the genetic finding (so-called "duty to warn") is reshaping the physician-patient healthcare partnership in the genetics community. So what began as an individual blood test can result in information with significant medical implications for not only that person, but for many family members.

The family dynamic. The psychological dynamics in each family are different, but it is important to remember that genetic testing on an individual is performed in the context of a family unit. The results of many blood tests create an emotional response - genetic testing is not alone in that. However, the unique emotional aspect of many genetic tests is that they are wrapped up in an already-existing family dynamic. Issues such as the expectations for a child (which may be different for the mother and the father) which change based on a test result, survivor guilt, the role of caretaker siblings, and anxiety about developing a condition if the testing was performed presymptomatically, can be added to the current manner in which a family handles its interactions. Although many family coping strategies are developed long before genetic testing is offered, the results may trigger emotional or communication issues that will need additional attention. If the primary-care provider does not have in-house resources to address the family dynamics, referral to a genetic center or other mental healthcare provider may be warranted.

So the next time you are preparing to order a simple blood test for a genetic condition, pause to consider the following checklist:

  • Is the patient an appropriate testing candidate?
  • Would you or a staff member be able to be an advocacy resource?
  • Is the patient (and when appropriate, the family) prepared for either a positive or a negative test result?
  • Does the patient understand the medical, psychological and social ramifications?
  • Do you have a referral list of appropriate specialists and/or genetic counseling resources to resolve any issues that cannot be handled in the office?

If you can answer yes to these questions, the blood test (although not simple) can be ordered with confidence.