Our ability to analyze and discover information from our genetic code is increasing at a rapid pace. So, how do you navigate this increasingly complex world? This blog summarizes a framework that I consider when breaking down the various genetic testing options available to families. My hope is for families to become more educated consumers of genetic testing by understanding the purpose, benefits, and challenges associated with each type of genetic test.
What does genetic testing look for?
It is important to note that everyone has changes to their genetic code. These changes make us unique, but they can also impact our health, development, and behavior. It’s the medical community’s role to find out which changes increase risks versus which genetic changes are simply part of normal human variation.
Different genetic tests look at different changes to the genetic code. This means no two genetic tests are the same! Based on what each specific test looks for, a person may discover different information about their genetic risks. Additionally, there are varying degrees of usefulness of that information for a person’s healthcare. In order to boil down this complex world, you can think of three categories of genetic tests: diagnostic, guidance, and recreational testing.
The purpose of diagnostic genetic testing is to identify or rule out a genetic condition that may be the underlying cause of a person’s symptoms. The hope is that by identifying a genetic condition, it will help families and healthcare providers understand how to better care for an individual.
Often, a genetic diagnosis provides answers that families have been searching for: What can we learn from others who have grown and developed with the same genetic condition? What are the strengths and challenges observed in people with this genetic condition? Do they have medical risks that we should be aware of such as seizures or heart defects? Is a specific treatment or therapy approach better for people with this genetic condition? What is the chance for this genetic condition to occur in our family again?
After receiving a genetic diagnosis, many families have found it helpful to incorporate the information from the diagnostic genetic test report into IEP or therapy plans. This can help families tailor a more personalized approach to therapy and emphasize the need for ongoing services. For example, individuals with a well-known genetic condition called Williams syndrome can have specific challenges in visual-spatial processing such as understanding left-right directions. Parents who are armed with this information can talk with providers and their school system about how to best work with these areas of difficulty. In fact, the Williams syndrome parent support group has a guide for teachers to help them understand the best approach for education given the specific strengths and challenges a child with Williams syndrome experiences.
Additionally, many states now have automatic qualification for early intervention services if a child is diagnosed with a genetic condition. Since a person with a genetic condition is expected to have greater and ongoing challenges compared to their peers, this can be used to secure ongoing intervention services.
Examples of diagnostic genetic tests that are intended to identify a genetic condition include chromosomal microarray, whole exome sequencing, fragile X syndrome testing, mitochondrial sequencing, and whole genome sequencing. The type of diagnostic genetic test that may be considered for an individual depends upon their symptoms and the questions their family and healthcare provider may have.
Since different diagnostic genetic tests look at different types of genetic conditions, the detection rate or ability to identify a genetic condition differs. It is important for families to understand the likelihood for diagnosis and the type of information that is obtained from such testing in order to determine if a diagnostic genetic test is beneficial for their family at this time. Also, just because one genetic test has been “negative” or “normal”, there may be other tests to consider next.
The main purpose of a guidance genetic test is to look at a person’s genetic code to understand the potential risk for medical concerns or to help with medication selection.
In comparison to diagnostic genetic tests where a person with symptoms is typically tested, you don’t necessarily have to have symptoms to receive benefit from a guidance genetic test. In fact, many healthy people find it helpful to understand risks that can be revealed from these types of genetic tests for proactive reasons.
Common examples of guidance tests are pharmacogenomic/pharmacogenetic testing, MTHFR testing, screening for mitochondrial or biochemical conditions through analyzing blood or urine, and carrier screening.
The benefits of guidance genetic testing vary depending upon the specific type of test. For example, a pharmacogenomic test looks for specific places in the genetic code associated with how a person metabolizes medications. Some people may find it helpful to understand their pharmacogenomic profile prior to undergoing surgery or after having adverse reactions or non-responsiveness to certain medications.
When considering this type of genetic testing, it’s important to keep in mind that it provides a snapshot of information and doesn’t take the full medical picture into consideration. Additionally, some tests have more evidence for impact on medical care than others.
This testing provides general health insight or ancestry information and was initially intended for the healthy population to better understand their genetic “traits”. While the term “recreational” downplays some of the impactful information that is increasingly available from home DNA tests such as 23andMe®, the results from these tests typically are not utilized in medical care without additional confirmatory testing.
Recreational genetic testing provides general health “insights” such as caffeine metabolism, lactose intolerance, or gluten intolerance. Health insights are not diagnostic, meaning you may or may not have symptoms even if you are deemed higher risk by this test.
Some recreational genetic tests providing health insights have expanded to include reporting of some very specific genetic changes that put someone at higher risk for genetic conditions. For example, some companies can report on a handful of genetic variants in a hereditary breast and ovarian cancer genes, BRCA1/2. It is important to know that this testing only looks for a small percentage of genetic mutations observed in the BRCA1/2 gene among thousands that have been identified. Not finding a higher risk for cancer from these tests does not rule out the possibility for the individual to develop cancer or for a hereditary cancer syndrome to exist in the family. These tests only look at a small slice of the bigger picture.
Despite the limitations that recreational genetic tests have for medical impact, they are good at analyzing a person’s ancestry from well-studied geographic regions. These tests also identify relatedness between family members and can identify an extended family tree that you may not have known you had!
It is great that genetic testing is becoming increasingly accessible! However, these tests do not all provide the same information. When considering genetic testing, becoming an informed consumer can help ensure that the information you receive is worth the cost of the test.
In order to make sure that you are getting the best bang for your buck, you may want to consider these questions:
What information am I hoping to receive?
How accurate are the test results?
Do I need to pursue additional testing for confirmation prior to using the results in medical care?
Can I talk to a trained professional, such as a genetic counselor, to help me select the best test?
It is important to know that you are not alone in navigating this complex world of genetic testing. If you would like to discuss these questions with a genetic counselor, you can find a GC local to your area by visiting the National Society of Genetic Counselors website at nsgc.org. If you have a child with delay or autism and are looking for diagnostic genetic testing, call mydevelopingchild at 801-931-6266. Our genetic experts can help you determine benefits of the testing based on your specific situation.
Please note: The test classifications described in this blog represent suggestions from the author’s personal experience gained in nearly a decade of speaking with families and physicians as a licensed/certified genetic counselor. Certain terms (ex: guidance genetic tests) may not be readily recognized by other healthcare providers, but the concepts underlying them will be understood.