You buy a €400 “Inherited disease DNA test” or “DNA test for health” online. Two weeks later, a report arrives in your inbox: “No increased risk of breast cancer detected.” It contains a sentence or two, maybe a fancy diagram. That’s it.
There is no further explanation, just the statement that you can show this ‘result’ to your GP.
You can find these offers everywhere. Yes, they look professional and they sound reassuring. But, in reality, they are based on automated SNP scans with no clinical context, which is why they conveniently avoid offering any medical interpretation.
So what are these DNA-based ‘risk score’ test – also called polygenic risk scores – and why can they be actively misleading, especially when someone has a genuine family history of disease, for example, breast cancer?
The explanation involves areas of genetics that are often misunderstood. But don’t worry — I can simplify things and make it much easier to understand!
What do DNA-based ‘risk scores’ check, and what do they miss?
Well, this Dino cartoon may look less impressive than a fancy “Genetic Health Prevention Test” report, but it illustrates a crucial difference between automated health reports and real genetic sequencing.
If you’ve ever arrived at an airport in Australia or New Zealand, you know how seriously they take biosecurity, protecting the country from unwanted pests and diseases. No salami, no bananas, no muddy sandals.
These items aren’t dangerous in themselves. In theory, though, they could be – particularly when combined, for example a bunch of muddy vegetables. So, they are checked, fumigated or even discarded.
But no one expects to detect a terrorist via a salami. If someone is carrying an actual weapon, that’s a job for different, more specific and sophisticated detectors.
It’s just like the situation with these online “DNA health tests”.
These risk score tests scan for common variations – SNPs – which are harmless on their own. They’re like hidden food items and muddy sandals in the suitcase. In theory, if there are enough of them present, there may be an increased statistical risk of cancer or other disorders. Then again, maybe not. It’s all just probability.
But what if there’s a real mutation? A pathogenic variant that does raise your risk? That’s the weapon on the dinosaur’s back. And the online DNA health tests cannot detect it.
That’s why we need proper genetic testing, such as a cancer gene panel, which uses sequencing and clinical analysis to screen for medically relevant mutations.
These tests can inform treatment plans, prevention strategies and real-life decisions, rather than just providing you with a checklist of your suitcase food items.
Don’t be fooled by such digital checklists.
If you have a family history of disease or simply feel that something isn’t right, salami alerts aren’t enough. Consult a clinical geneticist.
What exactly are these SNPs that automated online tests detect?
In simple terms, SNPs (Single Nucleotide Polymorphism) are small variations in the DNA sequence. We have variations in our DNA, because we are similar, but not identical.
For example, we all have genes that determine our hair colour, but some of us have brown hair, some black and some red.
These differences are due to SNPs: the little, harmless variations within the same “hair colour gene”.
Automated online DNA tests (also known as polygenic risk score tests) scan for exactly these small differences. They add them up and say: “Statistically, you might be more at risk.”
However, as previously mentioned, these mutations are not harmful. They are common variations, part of our human diversity.
A true mutation, such as a BRCA gene variant, is something very different. It is not a subtle difference like hair colour, but a structural error – a broken instruction in the genetic cookbook.
To detect such mutations, you need high-resolution DNA sequencing that reads the entire gene, base by base.
Anything else is merely a scan of the surface (or checking the suitcase for food).
Why might these tests be problematic?
It’s not the existence of polygenic risk scores that’s the problem. It is how they are presented that is problematic.
A negative result from one of these tests may create the false impression that there is no genetic risk.
However, these tests do not identify disease-causing mutations.
This means that a person could receive a reassuring report saying ‘no increased risk’ while still carrying a mutation such as BRCA1 or BRCA2 that is medically relevant.
For individuals with a genuine family history of disease, this can lead to false reassurance and delay an appropriate medical evaluation.
Are polygenic risk scores valuable?
Yes, but only in the right context.
When interpreted alongside proper genetic sequencing and clinical evaluation, polygenic risk scores can provide useful information.
For example, if sequencing identifies a possible mutation, additional genetic signals — including polygenic patterns — can help researchers to understand the extent to which that mutation affects an individual’s risk.
However, this only works when polygenic scores are used as an additional layer of information, rather than as a stand-alone ‘health test’.
Without proper sequencing and medical interpretation, polygenic risk scores are simply not an effective means of detecting hereditary disease.
In other words, while the test may appear thorough, it is not designed to detect the types of mutations that actually cause many hereditary conditions.