Duo and trio testing both involve testing biological relatives alongside the patient (called the "proband") to help interpret their results more accurately:
- Proband only: Only the patient is tested, without any relatives.
- Duo: The patient is tested along with one biological parent.
- Trio: The patient is tested along with both biological parents.
Important: parents who provide a sample for duo or trio testing will not receive their own separate report. A parent's sample is used only to help interpret the patient's (proband's) results - for example, to help rule out certain genetic variants by comparing the patient's sequence to their parents'. The report that's generated is for the patient being evaluated, not for the parent who provided a comparison sample.
Why duo or trio testing can be valuable: Comparing a patient's sequence to their biological parents' can rule out genetic variants that might not otherwise be clear from the patient's results alone. In one study of family trio analysis, children who underwent trio testing were almost five times as likely to receive a diagnosis as those for whom neither parent participated. Deciphering Developmental Disorders study