What is 30x and 0.4x Whole Genome Sequencing?

In a previous article, we covered clinical grade 30x whole genome sequencing (WGS). Here we go a step further and explain what terms like 30x and 0.4x actually mean when you see them attached to genome sequencing, and which one is right for which purpose.

About whole genome sequencing

Whole genome sequencing is a laboratory technique that reads both the coding (exon) and noncoding (intron) regions of your genome. It produces a comprehensive map of 100% of your DNA, which consists of nearly 6 billion letters. That is close to 6 billion data points for a single person's genome.

Whole genome sequencing versus genotyping tests

WGS is different from the traditional consumer DNA tests known as genotyping tests, which read only part of your genome. Genotyping tests, also called DNA chips or microarrays, are affordable and accurate, which makes them a reasonable entry point for many people. Genotyping is the most common type of consumer DNA testing sold online, and it is the technology used by companies such as 23andMe and AncestryDNA.

A genotyping test can read up to roughly 2 million data points and provides useful information across ancestry, health, medication response, wellness, nutrition, fitness, and sleep. So why choose whole genome sequencing instead? WGS is preferred when the goal is evaluating rare diseases, such as cystic fibrosis or Tay Sachs, or when someone simply wants the most complete genetic data possible. Where a genotyping test reads a fraction of your DNA, WGS reads all of it, across all of your over 30,000 genes.

The value of whole genome sequencing

WGS is the most powerful tool available for identifying genetic variants behind rare diseases and some forms of cancer, and it is also used to track infectious disease outbreaks. As the cost has dropped, it has become practical for everyday use. Understanding your genome in full puts you in a better position to act on what your genes say about your health.

What is 30x whole genome sequencing?

The key concept here is coverage. Coverage is a bit like megapixels on a camera. More megapixels generally means a clearer image, and in sequencing, higher coverage means higher data quality.

Coverage is the number of times the sequencing machine reads your genome. With nearly 6 billion letters, even a machine that is accurate 99.99% of the time would leave roughly 600,000 errors after a single read. To reduce that, sequencing services read the genome many times. Each additional read lowers the error rate, so higher coverage produces more accurate data.

When you see sequencing advertised, the x is what to look for. The number before the x is the coverage, meaning the average number of times your genome is read. With 30x WGS, your genome is read an average of 30 times.

Clinical grade whole genome sequencing

30x sequencing is considered clinical grade, which means the data is reliable enough to be used for health purposes. For example, clinical grade WGS data can support decisions about genetic predisposition to disease and which medications may suit you best. If you want your sequencing to be clinical grade, make sure it is 30x.

Sequencing combines 30x clinical grade sequencing with advanced bioinformatics processing and analysis, so you receive both high quality data and the tools to interpret it.

What is 0.4x whole genome sequencing?

Some companies, such as Nebula Genomics, have offered 0.4x WGS, which has prompted a lot of questions. Sequencing's bioinformatics team has worked directly with 0.4x data, and the short version is that we do not recommend 0.4x for health or wellness purposes, because it does not provide sufficient accuracy or data quality for that use.

At 0.4x, the genome is read less than a single time on average. That means the resulting data can contain significant gaps. After analyzing 0.4x data, including the imputation used to fill in gaps, our bioinformatics team confirmed it is not appropriate for health related analysis.

30x versus 0.4x sequencing

Both types of sequencing can be used, but for different purposes.

30x is the right choice when the data will be used for health or wellness, including evaluating a serious illness of unknown cause or assessing genetic risk for disease. 0.4x is generally aimed at recreational uses such as genealogy, though for genealogy specifically, genotyping tests from companies like 23andMe and AncestryDNA may offer more comprehensive insights at a lower price.

WGS coverage	Appropriate for
0.4x	Genealogy
30x	Health, rare diseases, wellness, deep genealogy, data exploration

The apps and reports in the Partner Marketplace are designed to analyze 30x genome sequencing data. Because most of them provide health insights, 0.4x data is not compatible with the platform.

Where to get 30x whole genome sequencing

Sequencing includes 30x WGS with its whole genome sequencing service. Rather than sequencing alone, the service pairs 30x sequencing with advanced bioinformatics analysis and a selection of health apps and reports, giving you 100% of your genome along with clear, usable guidance.

The service includes the Privacy Forever commitment, which means your data is kept confidential and is never sold or shared.

Using the Partner Marketplace

The Partner Marketplace offers apps across categories including health, ancestry, and nutrition. Good starting points include the Next-Gen Disease Screen, which analyzes your DNA across a large set of diseases, and Wellness and Longevity. If you have already taken a DNA test or had your genome sequenced, you can upload your data to get insights and personalized guidance.