Whole-genome sequencing vs. consumer DNA tests, explained

Two different technologies

23andMe, AncestryDNA, and MyHeritage all use genotyping arrays: a chip that reads a fixed set of hundreds of thousands of specific, already-known positions in your DNA. Whole-genome sequencing (WGS) and whole-exome sequencing (WES) work differently — they read your DNA directly, base by base, across a much larger share of the genome (WES focuses on the protein-coding regions; WGS covers substantially more of the genome beyond that). Sequencing typically produces a VCF file rather than the raw text export a genotyping array gives you.

Why the difference matters

A genotyping array can only report on the positions it was built to read. If a genetic variant relevant to a health finding sits outside that fixed set, an array simply has no data there — it’s not that the finding is negative, it’s that the position was never read. Sequencing-based files typically cover more of the genome directly, so they can in principle support findings an array-based file cannot.

Who sells whole-genome sequencing today

If you have never tested and want sequencing rather than a genotyping array, a few companies sell it directly: Mito Health offers whole-genome sequencing at 30x clinical-grade depth alongside a broader menu of lab panels on a membership model, and Nucleus Genomics sells a $499 whole-genome test screening for 2,000+ conditions, including a dedicated family-planning product for carrier screening ahead of having children. Both require a new sample and a new purchase. DNA Layer is built for a different starting point — a file you already have, whether that is a genotyping-array export or a sequencing VCF — which is why it costs less and needs no new sample.

If you have a WGS or WES (VCF) file

Upload it. DNA Layer reads whole-genome and whole-exome sequencing files in VCF format (.vcf or .vcf.gz), alongside the raw data exports from 23andMe, AncestryDNA, and MyHeritage.

A sequencing file is large — often more than a hundred megabytes compressed, holding several million variants — so it is read on your own machine, in your browser. Only the handful of markers our panel scores are sent to us; the file itself never leaves your computer.

One thing worth understanding about the format: a VCF lists only the positions where you differ from the reference genome. Everywhere else is left out. Read carelessly, that would delete every finding telling you that you do not carry a risk variant, and leave only the alarming half. DNA Layer resolves those omissions against a reference-allele map, so a sequencing file produces the same balanced picture an array file does — and it records which genotypes were read directly and which were resolved that way.

The reader is validated against the Genome in a Bottle reference genomes published by NIST — the same benchmark files the sequencing field uses to check its own tools — on both the GRCh37 and GRCh38 assemblies.