Skip to main content
Premium Trial:

Request an Annual Quote

DTC's Harms?

After the US Food and Drug Administration swung into action last year to stop 23andMe from marketing its service as a source of health information to consumers, one of the criticisms leveled at FDA was that there is no evidence that DTC tests have caused any harm.

Boston Children's Hospital's Vector Blog highlights a new paper which says errors from a DTC can cause harm.

Three Boston Children's researchers report that a patient whom they call Dr. J who had possible Crohn's disease received results from a DTC company (which they did not name) which found he had mutations in the TPMT gene – a trait that means he likely would have a toxic reaction to thiopurine drugs, which are used to treat Crohn's.

Boston Children's Catherine Brownstein, David Margulies, and Shannon Manzi, who reported the case in Clinical Pharmacology and Therapeutics, say that result was "questionable" because the company in question also found the same result in two of the patient's colleagues, even though their very different ethnic backgrounds made that result "highly improbable."

To double-check the result, the team used Claritas Genomics (a BCH spin-off) to genotype the Dr, J, his parents, wife, and children, and found that none of them had the TPMT gene mutation, nor did Dr. J himself. Dr. J did have a different variant in the gene which would confer a partial loss of enzyme function, they say.

If the erroneous finding from the first DTC firm had been used in Dr. J's treatment for Crohn's disease he would have received just one tenth of the standard thiopurine dose, which could have led his symptoms to worsen or his disease to progress.

Other methods may have been used to treat Dr. J, the BCH team admits. But what if the patient had leukemia, which also is treated with thiopurines, they ask.

In this case, the authors feel that more assistance in interpreting Dr. J's status may have been helpful, as "the most reasonable interpretation of the genotype was not presented clearly, and patients may not realize that they need interpretative support.”

"We are not advocating the end of DTC testing, nor are we universally denouncing DTC genetic testing companies. However, we feel that the interpretations must be accurate and reasonable, with adequate and freely available interpretation support for consumers and physicians," Brownstein and her colleagues write.