The plot thickened in the marketing of personal genetic tests.
The Food and Drug Administration fired off a new round of letters to a bunch of companies, pressing them to get their genetic tests approved by the government or explain exactly why that's not necessary.
The letters set up a showdown over the regulation of gene scans ordered directly by consumers, though the endgame may take a while.
Take, for instance, 23andMe, which sells its tests on Amazon.com. FDA notes the service tells people how they'll react to certain drugs, including some powerful blood thinners, and also calculates disease risks by summing up the variations in particular genes.
FDA says claims like that mean 23andMe is selling a medical device and that the company has never gotten the OK from the agency to do so.
"We disagree with the FDA's conclusion," 23andMe responded in a statement. The company says its data are "informational and eductional" and that people shouldn't make medical decisions without talking to a doctor.
Similar FDA letters went to Knome, Navigenics, Illumina and deCODE Genetics.
An agency official told the New York Times, FDA isn't looking to pull the tests from the market right away because until now the agency hadn't told the companies they needed approval for their tests.
We wanted to make sure we had read the letters right and asked the FDA for clarification.
"These tests are medical devices," a spokesman says in an e-mail. "As such, the Agency believes these tests must comply with FDA requirements, which includes that they are shown to be safe and effective."
By calling them regulated medical devices, FDA is also putting the companies on notice to monitor and report on problems with the tests after they're on the market.