Compare one-person, two-person and trio exome sequencing and understand how parental samples can improve genetic variant interpretation.
WES does not always involve one person
Whole-exome sequencing can analyze a single person or several relatives. The main distinction is how many samples are sequenced and how variants are compared. Singleton studies test one individual; duo studies usually test the patient and one relative; trio studies compare a child with both biological parents.
More samples do not guarantee a diagnosis. In selected cases, however, family comparisons can make interpretation more informative.
Singleton: sequencing one individual
Singleton WES may be appropriate when parental samples are unavailable or a one-person analysis fits the clinical question. The laboratory interprets variants using symptoms, inheritance expectations and available evidence.
A later targeted test in a parent or another relative may help clarify a specific finding. Ask which follow-up studies are included in the quote and which incur additional charges.
Duo: one patient and another family member
Duo WES analyzes two family members, most commonly a child and one parent. Comparing their variants can help establish whether certain changes were inherited and whether they fit the clinical presentation.
However, many inheritance questions are resolved more effectively when both biological parents are included. Discuss the limitations of a duo when one parent is unavailable.
Trio: a child and both biological parents
Trio WES sequences and analyzes a child alongside both biological parents. It can help identify de novo variants, evaluate transmitted variants and clarify some recessive inheritance patterns.
This approach may reduce the number of candidate variants requiring review in complex pediatric cases. Nevertheless, technical blind spots, VUS findings and negative results remain possible.
Can siblings or other relatives be included?
Yes. Clinicians may recommend extended family testing when comparing affected and unaffected relatives could help determine whether a variant segregates with disease.
Testing should be clinically justified and supported by appropriate consent. Genetic information can have implications beyond the person being tested.
Which approach is best?
The choice depends on age, symptoms, the family pedigree, availability of relatives, the diagnostic question and cost. Trio is not automatically the right answer for every case.
Ask what additional information each family member’s sample could provide, whether the quoted price covers all sequencing and interpretation, and whether you will receive an integrated family report.
Frequently asked questions
Are three affected people required for trio WES?
No. A trio usually consists of the patient and both biological parents, who are included to help interpret inheritance.
Can parents be tested after singleton WES?
Often, yes. Depending on the finding, targeted testing of parents may be possible; the laboratory determines the method and cost.
Scientific resources for further reading
For case-specific advice and current laboratory requirements, consult our services or genetic counseling team.
