“Some of the labs do have turnaround problems,” said Robert Cook-Deegan, MD, a research professor at Duke University in Durham, NC. “Most don’t. I have not heard major complaints from the national genetic testing labs (like GeneDx, Ambry, LabCorp, or Quest). I have heard of slowness at some of the state labs.” Some state labs have begun conducting their own BRCA testing to save money, he explained.

Myriad has tested more than 1.2 million women to date, Rogers noted. Because other labs are less experienced, there is also a greater risk of false-positive or false-negative results, Rogers argued.

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At the heart of the problem are variants of uncertain significance (VUS)—cases in which the interpretation of a sequence is not clear.5

“Myriad claims—and I think it’s probably true—that they have the lowest rate of variants of uncertain significance,” said Dr. Chung. “They’ve had the most experience…Many labs don’t have much experience interpreting sequences.”

 “The frequency of variants of uncertain significance, in terms of frequency, ranges from 2% for Myriad to 4% to 5% for other labs,” Dr. Chung explained. “So these are small differences. But, for the average oncologist who is not a molecular biologist or geneticist, I think there is some concern. It adds to the uncertainty.”

However, the VUS gap is likely to narrow as new entrants become more experienced, Dr. Chung and others said.

Rogers also questions other labs’ reliance on public gene databases for interpreting BRCA sequences.

“Every one of our competitors relies to some extent on public databases; the problem with public databases is, no standards exist for how they are curated and maintained,” Rogers said. “Public databases are not going to be accurate or good enough for clinical decision-making for a number of years.”

There are “issues” with the public databases, Dr. Chung acknowledged. “But the scientific community is trying to quickly clean up and curate the databases so that this turns out to be a short-term problem.”

“It is a work in progress,” she said.


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  3. Kepler TB, Crossman C, Cook-Deegan R. Metastasizing patent claims on BRCA1. Genomics. 2010;95(5):312-314.
  4. Furlow B. US firm corners exclusive license for RAD51C cancer gene. Lancet Oncol. 2012;13:e92. http://www.thelancet.com/journals/lanonc/article/PIIS1470-2045%2812%2970065-7/fulltext?_eventId=login. Last accessed April 15, 2014.
  5. Eggington JM, Bowles KR, Moyes K, et al. A comprehensive laboratory-based program for classification of variants of uncertain significance in hereditary cancer genes. Clin Genet. 2013; Nov 8. doi: 10.1111/cge.12315. [Epub ahead of print]