Medically reviewed by Eland Siddle, PharmD · Last updated July 2026
Whole genome sequencing (WGS) is a laboratory method that reads every letter of a person's DNA, all 3 billion base pairs that make up the human genome. Unlike tests that examine only a small slice of genetic information, WGS captures the complete picture in a single analysis.
For parents exploring genetic testing for their child, the options can be confusing. Gene panels, exome sequencing, ancestry tests, and whole genome sequencing all involve DNA, but they differ significantly in what they look at, what they can find, and what they can do over time. Understanding those differences helps you ask the right questions and make informed decisions alongside your child's healthcare providers.
This guide explains what whole genome sequencing is, how it compares to other testing approaches, and why completeness matters both today and years from now.
How Whole Genome Sequencing Works
Every cell in the human body contains a copy of your DNA. That DNA is organized into approximately 20,000 genes, but genes make up only about 2% of the genome. The remaining 98%, once dismissed as "junk DNA," is now understood to play important roles in regulating how genes are turned on and off.
Whole genome sequencing reads all of it. A laboratory processes a biological sample (typically a blood draw or a cheek swab), extracts the DNA, and uses high-throughput sequencing technology to determine the exact sequence of every base pair. The raw data is then analyzed by bioinformatics software and interpreted by clinical experts, including genetic counselors and laboratory scientists, to identify variants that may be relevant to health.
What the analysis looks for
Sequencing the genome produces an enormous dataset. The interpretation step is where the clinical value is created. Analysts look for variants, differences from the reference genome, and classify them based on current scientific evidence as benign, likely benign, of uncertain significance, likely pathogenic, or pathogenic. Variants in that last category are associated with genetic conditions or altered medication responses.
How WGS Differs from Other Genetic Tests
Not all genetic tests are the same. The table below summarizes the key differences between whole genome sequencing, targeted gene panels, and direct-to-consumer ancestry tests.
| Feature | Whole Genome Sequencing | Gene Panel | Ancestry / Consumer DNA Test |
|---|---|---|---|
| What it reads | 100% of DNA | A pre-selected set of genes (often dozens to hundreds) | Specific genetic markers (~0.1% of the genome) |
| Conditions covered | Broad: can screen for thousands of genetic conditions as science evolves | Limited to the conditions the panel was designed to detect | Not designed for clinical health screening |
| Medication insights | Yes: pharmacogenomic variants detectable | Only if the panel includes pharmacogenomic genes | No clinical-grade pharmacogenomics |
| Reanalysis potential | High: same data file can be re-interpreted as science advances | Low: new panel required to test additional genes | Not applicable for health use |
| Lab standards | Clinical-grade (CLIA/CAP for health use) | Clinical-grade (CLIA/CAP) | Research-grade; not intended for medical decisions |
| Genetic counseling | Typically included or available with clinical WGS | Varies by provider | Not included |
Gene panels: focused but fixed
A gene panel sequences only a defined set of genes. A cardiac panel might look at 50 to 100 genes known to be associated with heart conditions, for example. Panels are efficient and cost-effective for specific clinical questions, but they're built around what is known at the time of design. If a new gene is linked to a condition after the panel was developed, a new test is required to evaluate it.
Exome sequencing: a middle ground
Whole exome sequencing (WES) reads only the protein-coding portions of the genome, roughly 2% of total DNA. It captures most disease-causing variants identified to date, but misses variants in the non-coding regions that are increasingly recognized as clinically relevant. Like panels, the exome is a fixed snapshot; re-interpretation is possible but the dataset is incomplete compared to WGS.
Ancestry and consumer DNA tests: not clinical tools
Direct-to-consumer ancestry tests scan a very small number of specific genetic markers, enough to estimate heritage and detect a handful of well-known variants, but not enough to constitute a clinical health screen. They are not validated for medical use and should not be used to make health decisions. A negative result on a consumer test does not mean the genome is clear of health-relevant variants.
Why Reading 100% of the Genome Matters
Genetics is a rapidly evolving field. Researchers are continuously identifying new genes and variants associated with diseases and drug responses. When a test reads only a subset of the genome, findings made after the test was designed cannot be applied to that sample, because the data simply was not captured.
Whole genome sequencing preserves the complete data. A WGS file generated today can be re-analyzed in five years against a more complete scientific knowledge base without the need for a new sample or a new test. This is the core value of reanalysis: the science moves forward, and so does the insight.
For a child, this matters especially because many genetic conditions are not apparent at birth. Conditions with childhood or adolescent onset, medication sensitivities that only become relevant when a specific drug is prescribed, and carrier status that becomes important during family planning can all be identified from a single WGS dataset at the time when they are most actionable.
Where Fore Fits
Fore Genomics offers a comprehensive at-home pediatric genetic health screen for healthy children, built on whole genome sequencing. Because it reads 100% of a child's DNA rather than a limited panel, it is the only pediatric genetic screen on the market today that captures the full genome. The screen covers 1,000+ genetic conditions and 100+ medication interactions, and includes board-certified genetic counseling to help families understand results.
The sample is collected via a simple cheek swab at home, with no clinic visit, referral, or prescription required. The genome is stored securely (CLIA-certified and CAP-accredited lab, HIPAA-compliant, managed by DNAnexus with military-grade encryption), enabling lifetime reanalysis as new scientific discoveries are made without needing a new sample.
To understand how Fore compares to what your state already provides at birth, see State-Mandated Newborn Screening vs. Fore Genomics: What Parents Should Know. For a broader look at what newborn screening typically misses, read What Does Standard Newborn Screening Miss.
If you are weighing whether expanded genetic screening makes sense for your family, Is Pediatric Genetic Screening Worth It? walks through the key considerations.
Fore's role is not to replace your child's pediatrician or to diagnose conditions. It's to give families and their healthcare providers more information to work with. Results are always best discussed with a qualified medical provider or genetic counselor.
Ready to learn more? Visit Fore Genomics to explore the screen and see what a complete genetic picture looks like for your child.
Personalized Care, Not Prediction
Understanding what whole genome sequencing can find is only half the picture. What matters more is what you do with it.
Traditional medicine tends to ask one question: is my child sick? Fore is built around a different one: how do we help keep them healthy? That shift matters, because a genetic finding is not a diagnosis.
- A variant is not a verdict. Most children who carry one will never develop the associated condition.
- It points to personalized care, not a fixed fate. A finding identifies who may benefit from closer attention, not who is destined to get sick.
- It gives your pediatrician a head start. Depending on the finding, that can mean earlier eye or hearing exams, periodic heart monitoring, earlier cholesterol screening, avoiding a specific medication, or simply noting the result to watch over time.
- The goal isn't predicting the future. It's making your child's care more personalized from day one.
Fore's at-home whole genome screen covers 1,000+ conditions and 100+ medication responses, includes board-certified genetic counseling, and reanalyzes your child's genome over time as science advances. See what Fore screens for.
FAQs
What is whole genome sequencing, in simple terms?
Whole genome sequencing is a laboratory process that reads the complete sequence of a person's DNA, all 3 billion base pairs. It captures every gene and the regions between genes, producing a comprehensive data file that can be analyzed for health-relevant variants both now and in the future as scientific knowledge expands.
How is whole genome sequencing different from a standard newborn screen?
Standard newborn screening uses a heel-prick blood test to check for 30 to 80 specific conditions, depending on the state. It is not a genetic sequencing test. Whole genome sequencing reads the entire DNA sequence and can screen for thousands of conditions, including many that newborn screening does not cover and conditions that appear later in childhood rather than at birth.
Is whole genome sequencing the same as a consumer ancestry test?
No. Consumer ancestry tests scan a very small number of selected genetic markers, roughly 0.1% of the genome, and are designed for heritage estimation rather than clinical health screening. Whole genome sequencing reads 100% of the DNA and is conducted in a CLIA-certified laboratory with clinical-grade validation. The two products are not interchangeable for health purposes.
Can my child's WGS results be updated as science advances?
Yes, if the provider retains the original genome data file. Because WGS captures the complete genome, the same dataset can be re-interpreted when new gene-disease associations are discovered, without collecting a new sample. Fore Genomics offers lifetime reanalysis for this reason: as the science evolves, your child's genome can be re-evaluated against the updated knowledge base.
Does whole genome sequencing diagnose conditions?
No. Genetic screening identifies variants associated with increased risk or known conditions. It does not provide a clinical diagnosis. A positive or significant finding from a WGS screen should always be followed up with a physician or genetic counselor who can interpret the results in the context of your child's full medical history and recommend next steps.