What's the Difference between Genotyping and Full Gene Sequencing?

Genotyping, which predates modern DNA sequencing by about half a dozen years, provides yes or no answers for a predetermined set of genetic change questions. This has been a useful technology for population-scale genetic studies, and has been key in helping scientists better understand certain common diseases like type 2 diabetes. But genotyping gives a narrow view into the genome: it only looks at the most common genetic changes. While it may be the most efficient way to look at the tip of the iceberg, it doesn’t tell you anything about what’s under the surface.

Full gene sequencing is a totally different approach, designed to give a complete picture of your genes.

Full gene sequencing has been made possible by technological advances made in the past  decade. In 2007, a new type of analysis called Next Generation Sequencing, or NGS, burst onto the scene. Much like the introduction of smartphones around the same time, NGS has had a disruptive impact. Compared to what came before, NGS enables labs to examine genes in their entirety at a fraction of the cost and in weeks rather than months. Because NGS requires the implementation of new lab methods, instruments, and software tools to make sense of the data, it took a few years for this technology to mature into something that could be used for medical purposes. We are now in an era where NGS is routinely used to test for known disease-causing genetic changes, and even to identify new ones. This approach has been hugely successful, giving places like children’s hospitals and high-risk clinics fundamentally improved tools to help diagnose and manage patients with rare diseases or a strong family history of a genetic disease.

With Picture Genetics, we are kicking off a new era, where healthy people are empowered to peer into their own genes with a level of depth and quality which has historically been either impossible or unavailable.

How exactly does the technology work?

Each gene is a sequence of base pairs, or basic chemical compounds that are represented by four letters: A, C, G, and T. Let’s say one string of code on in your DNA reads like this: CTAGCTTG

That sequence would be the genetic code that tells your body how to make, say, a specific protein that performs an essential function for your health and development.

A variant, or mutation, in that sequence could look like this: CTACCTTG

Or this: ATAGCTTG

Or this: CTAGCTTC

Genotyping technologies lack the capability to look for every possible variation. So they’ll look for some of the most common, one letter at a time. (Some variants are harmless, and some are not. Harmful variants are often called mutations.)

Next Generation Sequencing reads your gene’s entire sequence and lines up each letter on a computer screen, so that our genetic curation scientists can see any variants that occur. Thanks to modern technology and our amazing lab scientists, we can be extra thorough—ensuring that if there’s something important to find in your genes, we have a very high probability of finding it, whether it’s common or not.

Here’s a quick summary of the two technologies:

Genotyping

• Examines one “letter” or location on a gene at a time
• Looks for the most common variants
• Cannot identify new variants

Next Generation / Full Gene Sequencing

• Reads the whole sequence of your gene (records each letter)
• Can find nearly any known variant on analyzed genes, regardless of whether it's common or rare
• Can find new variants, including ones expected to be pathogenic

Ultimately, both methods work when it comes to finding variants in your DNA. Genotyping is a valuable method, but full gene sequencing is the most thorough and is considered the “gold standard” for most genetic testing companies. That’s why we use it for all our tests.