The phrase "genetic testing" covers an enormous range of technologies — from consumer ancestry kits that read a fraction of a percent of your DNA, to clinical-grade whole genome sequencing that reads all of it. These are not different versions of the same thing. They are fundamentally different tests that answer fundamentally different questions.
Understanding what each test actually measures — and what it misses — is essential for anyone making decisions about their health based on genetic information.
What consumer genetic tests actually read
Consumer DNA tests from companies like 23andMe, AncestryDNA, and MyHeritage use a technology called genotyping. A genotyping chip reads a pre-selected set of known genetic markers — typically between 600,000 and 700,000 positions in your genome. This sounds like a lot, but your genome contains approximately 6.4 billion base pairs. A genotyping chip reads less than 0.01% of your total DNA.
This approach works well for its intended purpose: identifying common variants associated with ancestry, certain traits, and a small number of well-studied health conditions. It is fast, inexpensive, and sufficient for population-level pattern matching.
What genotyping cannot do is detect variants that were not pre-selected for inclusion on the chip. This includes:
- Rare variants that affect fewer than 1% of the population
- Novel variants not previously catalogued in genetic databases
- Structural variants — large insertions, deletions, or rearrangements of DNA
- Variants in non-coding regions between genes, which can still affect gene regulation
- Copy number variations that alter how many copies of a gene you carry
For clinical decision-making — especially when evaluating hereditary cancer risk, pharmacogenomic drug response, or rare disease — these blind spots are significant.
What whole genome sequencing reads
Whole genome sequencing (WGS) takes a fundamentally different approach. Instead of checking a pre-selected list of positions, WGS reads your entire genome — all 6.4 billion base pairs, every gene, every intron, every regulatory region, every position between genes.
At 30X coverage — the standard used in clinical diagnostics — every position in your genome is read an average of 30 times. This redundancy ensures 99.98% accuracy and enables the detection of variants that no targeted test was designed to find.
A typical 30X whole genome sequence identifies between 4.6 and 5 million variants per individual. This includes single nucleotide variants (SNVs), insertions and deletions (indels), copy number variations (CNVs), and structural variants. The raw data file — your complete genetic record — is approximately 100 GB.
The clinical difference
The distinction between genotyping and whole genome sequencing is not merely technical. It has direct clinical consequences:
- Diagnostic yield: For rare disease patients, WGS has a diagnostic yield of 25–50%, compared to approximately 10–15% for targeted panel tests and near-zero for consumer genotyping.
- BRCA coverage: Consumer tests check a handful of BRCA1/BRCA2 founder mutations. WGS sequences the entire genes, detecting thousands of possible pathogenic variants.
- Pharmacogenomics: WGS can identify variants across all pharmacogenes simultaneously, not just the subset included on a genotyping chip.
- Future-proofing: Because WGS captures your complete genome, your data can be re-analyzed as new variant-disease associations are discovered — without requiring a new test.
What about clinical panel tests?
Between consumer genotyping and whole genome sequencing, there are clinical panel tests (also called targeted gene panels or clinical exome sequencing). These are ordered by physicians and focus on a defined set of genes relevant to a specific condition or category — for example, a hereditary cancer panel might sequence 50–100 genes associated with cancer predisposition.
Panel tests are clinically validated and widely used. Their limitation is scope: they only examine the genes included in the panel. If your variant is in a gene not on the panel, it will not be detected. Patients who receive negative results on a panel test may still carry clinically significant variants that a whole genome sequence would reveal.
Additionally, panel tests are designed for a specific clinical question. If your health situation changes — or if you want to understand your genome across multiple areas (cardiac, neurological, pharmacogenomic, cancer) — you would need multiple separate panel tests. Whole genome sequencing answers all of those questions from a single test.
The permanence advantage
Perhaps the most underappreciated difference is what happens after the test. A consumer genotyping result is static — it tells you about the markers that were checked on the day the chip was designed. As science advances, your results do not update.
Whole genome sequencing data is complete. Because your entire genome was read, it can be re-analyzed against updated databases as new variant-disease associations are published. Dante Labs provides automatic report updates through the Genome Manager portal — meaning your 200+ clinical reports become more valuable over time, not less.
This is the core argument for sequencing once, comprehensively: your genome does not change. The science that interprets it does. A complete dataset ensures you benefit from every future discovery without requiring a new test.
Which test is right for you?
The answer depends on what you're trying to learn:
- Ancestry and traits: Consumer genotyping is sufficient.
- Specific clinical question with physician oversight: A targeted panel test is appropriate if ordered by your doctor for a defined condition.
- Comprehensive genetic picture for current and future health decisions: Whole genome sequencing provides the complete dataset — one test that covers every gene, every variant, every condition, with lifetime re-analysis.
Learn more about Dante Labs whole genome sequencing →
Get new posts from Dante Labs
Genomics insights, product updates, and clinical perspectives — delivered to your inbox.
