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What is trio testing?
Trio testing means including samples from a patient and both biological parents as part of an exome or genome test. Comparing all three samples can help determine whether genetic changes were inherited or are new in the patient. This can help clarify which changes may be related to the patient's condition and improve the chance of reaching a diagnosis.
Why are parental samples important in genetic testing?
Parent samples provide additional context that can help a laboratory interpret a patient's genetic findings. Comparing a patient's DNA with their biological parents' DNA can help determine whether a genetic change was inherited, and whether it may help explain the patient's condition.
Who can be included in trio testing?
- Best option: Parents
- Also informative: Other first-degree relatives such as siblings
- May also be considered: Second degree relatives, including biological grandparents, aunts, or uncles
What are the benefits of trio testing?
- Increase the chance of finding a diagnosis – trio exome testing can increase diagnostic yield by 7-15%1-4 compared to testing without parental samples
- Reduce uncertain results by more than 30% compared to multigene panels5
- Clarify genetic findings by learning whether a genetic change was inherited or not
- Reduce the need for additional follow-up testing by providing parental context in the initial analysis
The American College of Medical Genetics and Genomics (ACMG) support trio-based sequencing when possible.6
Flexible testing options for collecting family samples
While trio testing offers the most comprehensive insights, both parents may not always be with the patient when testing is ordered. GeneDx offers flexible sample collection options to help collect and return parent samples, even when family members are in different locations. If only one parent is available, duo testing can still provide valuable information to support the analysis process.
Trio
Patient + both biological parents
Duo
Patient + one biological parent
Proband only
Patient only
Send parent samples with the patient sample when possible
Reduce follow-up work
Submitting parent samples upfront can help avoid the need to recontact families, coordinate additional sample collection, and place new orders later, reducing staff effort and potential delays.
Simplify billing
Grouping testing into a single claim, under the child’s coverage or a single deductible, may help simplify billing and avoid separate charges across multiple individuals.
Trio testing available for exome and genome
Exome sequencing
Often the first, most effective step when a genetic cause is suspected. That’s because most known disease-causing variants are found within the exome.⁷
Genome sequencing
The most complete view of the genome, providing deeper insights beyond the exome when a broader search is needed.
How to order
Choose a test
Use the test catalog to search for a test. Each listing includes recommended use cases, methodology, and sample requirements—helping you select the right test for each patient.
Submit a sample
Request a sample collection kit, collect the sample, and ship it to our lab using the provided materials. Detailed instructions are included with every kit.
Receive results
Results are delivered securely through our online ordering portal, typically within 2–4 weeks.8 Each report includes clear findings, interpretation, and clinical guidance to support next steps in care.
Helpful resources
How trio testing changed Lola's diagnosis
Finding
Lola's infantile seizures remained unexplained until trio exome sequencing confirmed a disease-causing CDKL5 variant, enabling a diagnosis that informed treatment and ongoing care.
How trio testing changed Harper's diagnosis
Finding
Harper's developmental delays had no clear cause until trio exome sequencing confirmed a likely pathogenic SOS1 variant, leading to a diagnosis of Noonan syndrome and earlier syndrome-specific care.
Ready to bring genetic testing into your practice?
We’re here to support every step.