At-home DNA tests just aren’t that reliable

Clinical Articles

/ At-home DNA tests just aren’t that reliable

The field of genomic science is rapidly advancing, with commercial genetic tests becoming affordable and popular.

Taking these tests is simple. The company sends you a collection kit. You send it back with a saliva sample or cheek swab. The sample is sequenced and analysed, and before long you have your results.

However, upon a closer look you’ll find commercial genetic tests come with several hidden risks, and consumers often don’t understand what they’re signing up for. Here are some important factors to consider if you’re thinking of getting one.

Ancestry tests

The most common personal genomics tests are ancestry tests, offered by companies including Ancestry, 23andMe, FamilyTreeDNA and MyHeritage.

Ancestry tests are marketed as a way to explore your ancestral origins. But since different companies use different methods, and even different “ethnicity” categorisations, you may get inconsistent results. For example, Kristen V. Brown wrote for Gizmodo about how her saliva sample produced three different results from AncestryDNA, 23andMe and National Geographic.

In another example, a 2019 CBC Marketplace experiment involved sending the DNA of identical twins to five different companies. Each company returned surprisingly different results. Mark Gerstein, a Yale University bioinformatics expert, suspected the differences came down to different algorithms being used to process the raw data.

Health tests

The industry also offers tests for a variety of health conditions. A test may claim to provide you with predictions of your risk of developing breast cancer or Alzheimer’s. Carrier tests indicate whether you’re likely to pass on a particular condition to your child.

But users can get contradictory results here too. One company might indicate you’re at a heightened risk of colon cancer, while another might say you have reduced risk. Not to mention genes are only one factor in most complex diseases.

In an investigation by the US Government Accountability Office, tests from four companies delivered highly varied results. The report concluded:

The test results we received are misleading and of little or no practical use to consumers. […] The experts we spoke with agreed that the companies’ claims and test results are both ambiguous and misleading.

A genetic test in a medical clinic is governed by many rules and laws. A commercial test bought online is mostly subject to the company’s own terms and conditions and privacy policy. And, as we all know, these terms and conditions are often too long and unreadable for most people.