Polygenic Risk Scores: The Better Choice for DNA Testing

In 1990, the Human Genome Project began and was completed in 2003. It took 13 years of large teams of researchers to sequence the human genome. Now, 20 years later, the great advancements in biotechnology have led us to commercially available genetic tests that give you results within a matter of weeks. The rise of direct-to-consumer DNA testing will begin to integrate the normality of using your genetic information in everyday life. However, as this is such a new concept, it is hard to know how to choose and interpret a DNA test.

Competitor analysis

Multiple companies are offering genetic tests in the South African market - which should you choose? The table below gives you a number of factors to consider when purchasing a DNA kit, but one of the most important factors to draw to your attention is the approach: the polygenic risk scoring (PRS) approach or the single-gene approach. 

You may have seen that BioCertica has implemented a PRS approach in our DNA testing, and you can read more about the technical aspects of this here. However, it is important to understand the difference between these approaches. 

The Differences in Methods for DNA Testing  

Before we get too technical, let us simply explain the difference between the two methods for doing genetic testing. The more traditionally used method is the single–gene analysis approach which gives information on a few genetic variants at a time. However, complex traits are not determined by a few genetic variants but rather by hundreds to thousands of genetic variants. Therefore, PRS is a more advanced method approach because it takes all of the hundreds to thousands of SNPs that are associated with the trait of interest into account and calculates a single net effect. To put this simply, the single gene approach is like trying to figure out the picture from a few random pieces of a puzzle, whereas PRS gives you all the pieces of the puzzle put together so you can see the image very clearly.

Now let’s break this down more technically. A network of complex biochemical networks determines complex traits. SNPs will affect the metabolites in these interconnected pathways. Looking at one SNP in isolation isn’t effective because other SNPs will also determine the trait at the end of the network. Also, not all SNPs are weighted the same, meaning that one SNP might be much more influential on the trait than another. In PRS, these different effect weights for all the SNPs are taken into account so that the entirety of the network is considered as a whole to get a far more accurate depiction of the results. 

How the Reports Differ

We can look at a specific example. Say a person would like to know your genetic predisposition to oestrogen production. Here is a screenshot of BioCeritca’s PRS results. We list some of the genes that contain SNPs that are tested here. As you can see, there is a clear answer to the initial question; this person has a genetic predisposition to increased estrogen levels. Now compare that to the results of single gene analysis; they provide the genotypes for a hand full of SNPs and try to give some indication of the impact of that SNP. However, there is no clear and concise answer to the question. Without knowing the effect weight of each SNP, you can’t interpret an accurate conclusion, and you only have a portion of the information available.

Where do PRS Come From? 
Now you may wonder how we know the effective weight for each SNP and which SNPs are associated with traits. This information comes from Genome-wide association studies (GWAS) which use large cohorts of people and their DNA samples to make hard/sure links between SNPs and the trait under investigation. These studies are published in peer-reviewed journals, making them highly credible and reliable. This is made available on public databases like the PGS catalog and GWAS catalog. However, we at BioCertica have additional criteria for the studies that we use, such as the size of the study. Read more about this here. Additionally, to maintain complete transparency and trust between our users and us, we provide the links to these studies.

Other benefits of BioCertica

By using an App as our platform, we can easily update our results as new GWAS studies are released. This means adjusting results that they are even more accurate and adding in results for new traits. These updates are free to our users. Due to this BioCertica is a long-term investment in healthcare where as other companies work on a “once-off purchases” basis. We also provide comfort to our clients by giving them direct access to the studies that we used to determine their results; this transparency creates credibility, authenticity and trust, which is lacking in other companies.

As DNA testing becomes more and more prominent in health care, we feel that it is important to be as educated as possible so that you can make informed decision about your purchases. Ultimately, the choice is yours, but we do hope that now you have a greater insight when it comes to purchasing a genetic testing kit.