Watson said researchers should not expect a "windfall" for revealing the sequence of DNA that encodes various genes.
"DNA's importance flows from its ability to encode and transmit the instructions for creating humans," he wrote. "Life's instructions ought not be controlled by legal monopolies created at the whim of Congress or the courts."
Myriad insists it's not seeking to stop testing. Officials said in a statement that they have conducted close to 1 million BRCA tests and about 95 percent of the results have been paid for through public or private insurance or Myriad's financial assistance program.
On research, they said 18,000 scientists have done studies on BRCA genes and published more than 9,000 papers since they first filed for a patent in 1995.
In an email statement, Rebecca Chambers, a company spokeswoman, said Myriad's mission is providing women with information that could help save and improve their lives.
"Over the last twenty years, the company has invested hundreds of millions of dollars, and countless hours, educating patients and health care providers on the role BRCA 1 and BRCA 2 play in hereditary breast and ovarian cancer," she said.
Research, however, may soon yield another problem. Scientists expect to be able to sequence a person's entire genome in a few years for as little as $1,000, or less than one-third of Myriad's BRCA test price.
Doctors could cut out many diagnostic "middle men" by evaluating all known mutations that raise disease risk at once and recommending preventive measures, said Kahn, from the Hopkins bioethics institute.
But the court ruling upholding a gene patent could discourage doctors from revealing patented mutations because the patent owners control the testing for those, he said. That would violate medicine's "bedrock principle" that people should be able to know their personal medical information.
For now, some dismissed fears of big and immediate consequences, including Tim Worrall, a biotech patent attorney with Dorsey & Whitney who was not involved in the case.
That's because the courts will likely have more to say. The Supreme Court has indicated that it would set limits on patents in a recent ruling in a separate case about medical processes. In that case, Mayo v. Prometheus, the high court found that a method used to determine how much drug to administer to safely and effectively fight disease could not be patented because drugs are metabolized through natural processes.
The legal uncertainty could make investors "careful" about investing in companies whose patents are DNA-related until the Myriad case is resolved, Worrall said. And biotech companies aren't likely to scramble to patent more genes, he said.
"Companies will continue to enforce their patents to DNA but may choose to watch the appeal carefully because the outcome of this case will determine the best course of action to enforce patent rights," he said. "A decision that reverses the court's conclusion that DNA is patentable would have a negative impact on the biotech industry."
The next court to hear the Myriad case, either the full appeals court or the Supreme Court, needs to provide clarity, said Hank Greely, director of the Center for Law and the Biosciences at Stanford University.
In its ruling, the appeals panel said Myriad could patent gene sequences but not its methods of analyzing them. So Greely said the company may not have the right to stop others from developing a different method of comparing patients' mutated and normal genes to determine disease risk. Myriad doesn't dispute this, as long as the test doesn't infringe on Myriad's intellectual property, company officials said.
In the end, the calendar may usher in the biggest changes. Greely noted that Myriad's patents will begin expiring in 2015 and that most other gene patents, established years ago, expire in less than a decade.