Institute of DNA

Don’t Spit in a Tube Until You Read the Fine Print.

Direct-to-consumer DNA tests offer unprecedented insights—and unprecedented risks. We evaluate the clinical utility, privacy terms, and actual accuracy of top genetic tests.

Raw Data Discrepancies

A critical flaw in the direct-to-consumer genetic testing model is the widespread practice of downloading "raw data" and running it through third-party analysis tools like Promethease.

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The False Positive Problem

A 2018 study in Genetics in Medicine analyzed 49 patient samples who brought direct-to-consumer raw data to a clinical lab for confirmation. 40% of the variants reported in the raw data were false positives.

Consumer microarray chips are designed to detect common variants (like those used for ancestry and common traits). They are notoriously unreliable for rare pathogenic variants (like BRCA1/2 or Lynch Syndrome).

When you download your raw data text file and upload it to a third-party health site, those services parse every single SNP (Single Nucleotide Polymorphism) recorded. If the microarray misread a rare variant, the third-party tool will flag it as a severe health risk, causing severe patient anxiety.

Why does this happen?

  • Probes are imperfect: Microarrays use chemical probes. Sometimes they bind to the wrong piece of DNA.
  • Lack of clinical validation: Unlike a clinical lab (which might use Sanger sequencing to confirm a dangerous mutation), DTC companies do not validate the uninterpreted raw data.
  • Disclaimer loopholes: The terms of service strictly state raw data is "unvalidated" and not intended for medical use.