sjohnson@mercurynews.com

The U.S. Supreme Court on Thursday unanimously ruled that naturally occurring human genes can't be patented, easing widespread fears that companies could jack up the price of diagnostic tests based on that genetic material and limit research that might save lives.

But the decision could make it harder for some Bay Area biomedical companies to lure investors and innovate, industry experts said. While the ruling also affirmed the right to patent synthetic genes made in laboratories, the experts called it a blow to firms that rely solely on patents for natural genetic material.

"This is a troubling turn of events," said Gail Maderis, CEO of BayBio, which represents Northern California firms. "We are the only country that has defined patentability so narrowly. For us to take such a restrictive view puts us at a disadvantage."

In its ruling, the court tossed out gene patents that Utah-based Myriad Genetics used for its proprietary test of breast and ovarian cancer in women with genetic mutations. Myriad's test is designed to spot the mutations, which can significantly boost a woman's chance of developing the diseases. Actress Angelina Jolie, whose mother died of ovarian cancer, took the test before deciding to undergo a recent double mastectomy.

The court's ruling, written by Justice Clarence Thomas, declared that "laws of nature, natural phenomena and abstract ideas" aren't patentable. Therefore, it added, "we hold that a naturally occurring DNA segment is a product of nature and not patent eligible." Genes are subsets of human DNA, the hereditary material that makes up humans and almost all other organisms.

The patent case had drawn intense national interest. That was partly due to Jolie's disclosure, but also because the decision was anticipated to have broad social implications.

For one thing, DNA has become a lucrative commodity. Over the past 30 years, the government has issued patents for thousands of human genes, associated with colon cancer, Alzheimer's disease, muscular dystrophy and other ailments. A study last month in the journal Genome Medicine concluded that more than 40 percent of the human genome has been patented so far. It's unclear how many of those patents will be voided by the ruling.

Businesses have argued it's been essential for them to patent genes in order to justify the enormous investments they often make to conduct DNA research. Without legal protection for their inventions, they said, competitors could simply copy their work.

But consumer advocates claim the patents gave companies monopoly power which they sometimes abused.

Myriad had been accused in the case of often charging more than $3,000 for its genetic tests and suing others to prevent them from offering cheaper tests related to the patented genes. Critics also said many scientists avoided doing research on the patented genes, fearing they also could be sued.

"Removing the patents on the building blocks of life ensures that scientific discovery and medical care based on insights into human DNA will remain freely accessible and widely disseminated, not hidden behind a vast thicket of exclusive rights," said Dr. Jeremy Lazarus, of the American Medical Association.

Business advocates, however, had a mixed reaction.

Many biotech companies that have patented naturally occurring DNA also have patented synthetic versions, which they can continue using for diagnostic tests, drugs and other health-related products, they noted. It's unclear how many companies in the Bay Area might be affected by the court's ruling.

But for companies that just rely on natural-DNA patents, "that could be a problem," said Morrison & Foerster lawyer James Mullen. "Those people would be in trouble, potentially."

Contact Steve Johnson at 408-920-5043. Follow him at Twitter.com/steveatmercnews.