As much as 40 percent of direct-to-consumer DNA tests are wrong

As much as 40 percent of direct-to-consumer DNA tests are wrong

2 April 2018

By Carl Velasco; Tech Times
A new study calls to question the accuracy of at-home DNA testing kits marketed by a number of popular genetics brands. Companies such as 23AndMe and DNA Direct make it seem easy to determine bloodlines and diagnose certain vulnerabilities in a person’s genetic makeup, but data pulled from such testing methods are see as risky.

Direct-to-Consumer (DTC) DNA Tests and False Positives

A new study by diagnostics company Ambry Genetics highlights that false positives are one of the greatest weaknesses of these kinds of at-home tests. Take this analogy from Geek: one’s genome is akin to a book about a person, with each gene representing a different chapter, and their DNA sequence serving as the letters that constitute the words.

A legitimate genetics lab will be able to read each word in specific chapters, ensuring that large sections aren’t missing or duplicated. Direct-to-consumer genetic testing kits, meanwhile, employ a method called SNP array, reading only specific letters but not whole chapters. “Many of these DTC labs also release raw data to the consumer,” wrote Stephany Tandy-Connor in a blog post. She is a genetic counselor for Ambry Genetics.

The company’s research saw that at-home DNA testing kits have a 40 percent false-positive –– which proves that it’s important to have raw data analyzed by official genetics labs before making any further steps regarding one’s genetic makeup. “Our results demonstrated a 40% false positive rate highlighting the importance of confirming DTC raw data alterations in a clinical laboratory that is experienced in complex alteration detection and classification, especially prior to making any medical management recommendations,” wrote Tandy-Connor.
Diagnostic DNA Testing

Direct-to-consumer genetic tests are advertised and sold directly to the public –– promising to offer information about one’s ancestry, risks of certain diseases, and other non-phenotypic traits, such as eye color. There has been an increase of such tests because of growing interest in personalized health care. But these tests are not to be taken as diagnostic truth, because they might only offer risk information under only a limited set of conditions.

Access to information about one’s genetic makeup isn’t the issue here. The problem is when people intend for their at-home DNA testing results to dictate how they’ll manage their health moving forward. This is potentially dangerous, because raw data might lead to inappropriate changes in their care, the researchers say. “It is our hope that confirmatory testing and appropriate clinical management by all health-care professionals accompany DTC genetic testing for at-risk patients.”

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