Exome and genome:
How testing works

Because no single test is suitable for all circumstances, your healthcare provider will determine the appropriate option based on your symptoms, medical history, and family history. 

The American College of Medical Genetics and Genomics recommends exome or genome as a first-line test for developmental delay, intellectual disability, and congenital anomalies.¹

The National Society of Genetic Counselors recommends exome or genome testing for all individuals with unexplained epilepsy. This guideline is endorsed by the American Epilepsy Society.² 

When choosing to pursue genetic testing, patients or their guardians must give informed consent for clinical genetic testing. This means that the individual has been educated about the risks, benefits, and limitations of genetic testing and has agreed to move forward with testing. GeneDx’s consent also covers the patient’s options for secondary findings and being contacted in the future for research purposes.

Click here to view GeneDx’s informed consent form, as well as additional information about options for future contact, use of de-identified data, and specimen retention.

When you get exome or genome testing, genetic changes may also be identified that are unrelated to the reason your provider recommended testing. These are known as “secondary findings.” 

The American College of Medical Genetics and Genomics (ACMG) has created a list of specific “secondary findings” genes known to be associated with health conditions for which medical screening and/or treatments are available.

Most conditions on this list can increase the chances of developing certain cancers or heart conditions, or change the way your body breaks down, stores, and uses different substances (called metabolic conditions). Certain conditions, such as Alzheimer’s or Huntington disease, are not included. 

Exome or genome testing identifies secondary findings in approximately 2% to 3% of people^3-6. This means that testing does not identify a secondary finding in 97% to 98% of people. 

These types of secondary findings are optional to receive, so talk to your healthcare provider before ordering your exome or genome test about whether you would like them. During the consent process, you and your genetics professional will discuss whether you want to opt-in or opt-out of secondary findings. They will help you reflect this choice on your genetic testing consent form and in the order they place.

Testing two or more biologically related family members and comparing the results to a person’s DNA is called “trio testing.” Samples from biological parents can provide the most information. However, any blood-related family member can contribute.

Trio testing is valuable because it:

• increases the chance of finding the gene change causing the symptoms
• decreases the chance of unclear or uncertain findings

Usually, your doctor will collect either a blood sample or a cheek swab (also known as buccal swab). Blood specimens are typically collected in your doctor’s office, whereas cheek swabs can also be used at home to collect cheek cells. 

Step 1: Once GeneDx receives your sample, we analyze it with the most up-to-date technology, scanning your genetic material for changes that might link to a disease. 

Step 2: Next, your results are interpreted by our team of genetics experts, who write your personalized report. 

Step 3: Finally, the report is delivered to your doctor, who will discuss the results with you. 

The exact information found in an exome/genome report will vary, although results will typically contain details like: 

• test(s) requested
• the reason your healthcare provider ordered testing
• results and description  
• any gene changes identified that may have a role in disease
• a summary of the findings 
• guidance for next steps

After receiving your results, your healthcare provider will discuss them with you, helping you understand the next steps. They may also provide treatment plan recommendations and/or connect you with additional resources. With a referral from your doctor, GeneDx also has genetic counselors available for phone or video appointments.

A genetic counselor is a healthcare professional trained in medical genetics and counseling, and skilled at communicating the complexities of genetic testing in a way that’s easy to understand. During a genetic counseling session, a genetic counselor may:

• review your family history
• explain the benefits and limitations of exome and genome testing
• discuss your test results
• offer resources and support
• help you understand whether additional family members should be tested

Learn more about genetic counselors here.

A variant of uncertain significance (VUS) means we identified a genetic change, but based on what the medical field knows today, we cannot clearly determine whether the finding is related to a health condition at this time.

Doctors consider treatment options based on published guidelines and supported research, which advise not making a change in your medical care based on a VUS. Genetics is a constantly advancing field, with new disease gene relationships discovered regularly.

With exome testing, patient results can be reanalyzed to take advantage of scientific progress. GeneDx offers one reanalysis at no additional charge with every exome order. Our data show that optimal reanalysis occurs every 2-3 years. Talk with your doctor about reanalysis options.