“Why didn’t the $99 DNA test reveal the reasons for the high incidence of colon cancer in my family?”
We were recently asked this question from a woman who had paid for a popular DNA test for her entire family and did not get the answer to her question. There are many genetic and genomic testing options – some are disease-specific while others are designed for broader screening, therefore, as a consumer you need to understand if you are getting the right tool for the job.
Here’s what to expect from a $99 genetic test:
$99 worth of DNA testing
Have you checked how much a medical genetic test for a single gene costs? The bill typically runs to about a thousand dollars, give or take a few hundred. The price tag reflects the level of scrutiny required to provide clinically relevant genetic diagnostics. Clinical tests have to scrutinize the entire coding regions of genes through sequencing. Meanwhile “fun genomics” never sequences entire genes; instead it relies on a standardized panel of a few common variations that have little to do with disease predisposition.
Provide you with fun information – Fun Genetics vs. Medical Genetics
If the genetic testing company analyzing your genomic data to claim that not only are you are the “third cousin” of Dustin Hoffman but are also related to half of the artists on Hollywood’s Walk of Fame, you cannot expect it to take your medical issues seriously. If you want to “reconnect” with related celebrities, perfect! But, if you are seeking information on ways to prevent a certain cancer being passed down to your children, then a $99 test will only provide you with a limited view of your DNA and you’ll need a more detailed genetic test.
Test your DNA with older technology
Ancestry testing relies on ‘markers’ on sex chromosomes and mitochondria, along with a set of randomly distributed markers in your genome for calculating relatedness. To make the genetic test a little more medically relevant to consumers, companies add selected markers associated with diseases, but these tests cannot capture rare novel mutations, which are most informative. That’s why genotype based testing is limited and does not identify mutations responsible for colon cancer – these are too rare for genotyping arrays. Next Generation Sequencing technologies (NGS) are more sensitive in detecting rare variations that may have major impact on health and provide more specific and medically relevant recommendations on disease predisposition. But they are also an order of magnitude more expensive. If you have a strong family history of colon or breast cancer, NGS analysis will be able to identify the underlying genetic variations, which can be validated by standard point mutation analysis or sequencing. The drawback of whole genome sequencing is that it uncovers too many novel variations that today, cannot be accurately classified as disease-causing or benign because of sparse medical annotations for such rare mutations. The computational algorithms for analysis of novel mutations are not robust enough for accurate prediction of disease liability, but are rapidly improving with the publication of new genetic studies that link these mutations to specific diseases. Many genetic testing providers appeal to consumers to contribute their genomic data for humanitarian research. To avoid unnecessary frustration we advise you to consult with your physician, genetic counselor or at least the DTC genetic testing company’s representative to ensure that the test is designed to answer your specific questions or health concerns.
A checklist you could use before getting a genetic test
- Be sure that you have a reason to get a genetic test. If your reason is for fun, don’t spend any more than $99 on a genetic test. If your reason is for health related purposes, ensure you get accurate information from a test fit for this value.
- Does the service provider offer genetic consultation to explain the implications of test results for you and your family – cheap test providers outsource genetic counselling and charge extra fees.
- Did you get life and health insurance in order – in many jurisdictions it is advised to get insurance before committing to testing
- Ask your friends and family for references, and check the social media for feedback on chosen provider.
If you would like to learn more about genetic testing providers, continue reading this related blog post: “How To Choose a Genetic Testing Provider”. If you enjoyed this post and want to read more, please follow us on Twitter or become a fan on Facebook.