Clinical OMICS

MAY-JUN 2018

Healthcare magazine for research scientists, labs, pathologists, hospitals, cancer centers, physicians and biopharma companies providing news articles, expert interviews and videos about molecular diagnostics in precision medicine

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Diagnostics 16 Clinical OMICs May/June 2018 www.clinicalomics.com Wrangle Over DTC Results Ambry Study Highlights 40% False Positives, 23andMe Defends Tests, and Experts Weigh In By Alex Philippidis A study by Ambry Genetics researchers showed that as much as 40% of the variants in a variety of genes reported in the raw data of direct-to-consumer (DTC) tests were false positives. The researchers, and Ambry itself, said the study findings raise questions about the accuracy of DTC genetic testing—while the largest DTC test provider in turn has raised questions about the study and has defended its testing results. A team of eight Ambry researchers analyzed the raw data of 49 patients who were referred to the clinical diag- nostic lab of Ambry Genetics for confirmatory testing of variants previously identified by DTC testing between January 2014 and December 2016. The patients previously shared these raw test data with their medical providers. The researchers found that two out of every five variants noted in the DTC raw data were incorrectly reported and could not be verified by further diagnostic lab tests. In eight instances, according to the study, the variants that were present were mis- understood by third-party interpretation services. "While having access to raw genotyping data can be informative and empowering for patients, this type of information can also be inaccurate and misinterpreted," the researchers concluded in the study "False-positive results released by direct-to-con- sumer genetic tests highlight the importance of clinical con- firmation testing for appropriate patient care," published in Genetics in Medcine. 'Educational Piece' While the study cast doubt on the accuracy of DTC testing broadly, the authors chose not to disclose the DTC compa- nies whose results were examined. "This was Ambry's choice," said Stephany Leigh Tandy-Con- nor, study leader and supervi- sor, genetic counseling–cancer at Ambry. "We did not want the spe- cific DTCs and/or the third-party interpretation services involved to become the focus of the paper. Instead, we really wanted this to be an educational piece for not only the general public but also for med- ical providers who may not have a strong background in genetics." According to Tandy-Connor, some discrepancies in the results may be explained by technical dif- ferences between the various testing methods used. The study's rela- tively small cohort also shows how few people who get DTC results don't seek confirmatory testing. That patient cohort was nearly all-female (45 of 49; 92%), and mostly dane_mark / Getty Images

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