Introduction — Beyond Chromosomal Testing: One More Step Toward Reassurance
Even when chromosomal screening (PGT-A) is normal, some genetic risks—such as those linked to autism or childhood cancers—remain unseen. To address this, researchers from Stanford University developed Orchid PGT-WGS (Whole-Genome Screening). This article explains its principles, clinical use, and key considerations through the lens of Better Freeze’s evidence-based approach.
1. What is Orchid PGT-WGS?
Orchid PGT-WGS analyzes over 99% of an embryo’s genome, enabling simultaneous evaluation of multiple parameters previously tested separately—chromosome count (PGT-A), monogenic disorders (PGT-M), de novo mutations, and polygenic risk scores (GRS). The panel includes more than 200 autism and neurodevelopmental genes, 900 congenital anomaly genes, and 90 cancer-related genes.
2. How it differs from traditional testing
Its core advantage is consolidated insight: one workflow that reviews chromosomal, monogenic, de novo, and polygenic signals. The table below highlights how PGT-WGS compares with legacy PGT options.
| Item | PGT-A | PGT-M | PGT-WGS |
|---|---|---|---|
| Main purpose | Detect chromosomal aneuploidy | Confirm known single-gene disorders | Evaluate chromosomes, monogenic conditions, de novo variants, and GRS together |
| Genome coverage | ~1% | ~1% | >99% (whole genome) |
| Insights | Limited | Condition-specific | Broad view of autism, congenital anomaly, and chronic disease risks |
3. How the test works (approx. 2 weeks)
Clinics follow a familiar PGT timeline. Expect the sequence below when planning an Orchid PGT-WGS cycle.
- Egg retrieval and embryo culture (Day 5–7)
- Embryo biopsy and cryopreservation
- Whole-genome sequencing
- Genetic counseling and result discussion
- Selection and transfer of normal/low-risk embryos
4. Who may consider this test
PGT-WGS is not routine for everyone, yet certain scenarios benefit from the added clarity it delivers.
- Those concerned about genetic conditions despite normal chromosomal results
- Couples wishing to check de novo mutations without known family history
- Patients seeking to analyze multiple risk types in one IVF cycle (e.g., overseas residents)
- Those considering long-term health planning, including chronic disease risk
5. Limitations and cautions
PGT-WGS reduces but cannot eliminate genetic risks. Environmental and unknown factors remain. Costs are higher than separate PGT-A/M tests (approx. USD 6,000–8,000 per cycle in North America). GRS reflects statistical likelihoods that vary with lifestyle. Genetic counseling is recommended for interpretation.
- Risk cannot be zero
- Chronic risk is probabilistic
- Expert interpretation is essential
6. Conclusion — Understanding brings reassurance
Orchid PGT-WGS offers a new way to assess genetic risks that traditional PGT could not fully capture. However, no test can remove all risks. Deciding what to know and how to use that knowledge is best done through dialogue with your physician and genetic counselor.