Myriad Genetics was dealt a blow on Thursday when the US Supreme Court ruled that isolated human DNA cannot be patented.

The decision ends the Utah-based company’s monopoly on the genetic testing of two human genes associated with breast and ovarian cancer, BRCA1 and BRCA2.

But the unanimous ruling said that synthetic molecules known as complementary DNA (cDNA) can be patented because it is "not a naturally occurring product".

The lawsuit was filed in 2009 by a group of plaintiffs that claimed Myriad’s intellectual property rights had stifled research and were invalid because they "covered naturally-occurring" products.

In April, the America Civil Liberties Union argued that the firm had "locked up a building block of human life" by having the right to stop other researchers from using the genes for clinical purposes.

Marks & Clerk european patent attorney and partner Dr Gareth Williams said in a statement today that it would be "an understatement" to describe the ruling as disappointing news.

"By declaring isolated forms of human DNA patent ineligible, it robs genome research companies of a huge commercial incentive to continue researching into DNA. This research is vital if we are to develop effective DNA-based treatments or diagnostics for diseases like cancer or inheritable illnesses.

"The decision goes against a recent equivalent in the Australian courts, which declared isolated DNA to be patentable. The US Patent and Trademark Office has granted patents on DNA for over ten years now and the European Patent Office has also continued to grant gene patents."

But Myriad remains positive over the court’s decision to leave cDNA patents in place.

Myriad president and CEO Peter Meldrum said; "We believe the Court appropriately upheld our claims on cDNA, and underscored the patent eligibility of our method claims, ensuring strong intellectual property protection for our BRACAnalysis test moving forward."

Image: Human DNA may not be patented. Photo: Courtesy of FreeDigitalPhotos.net.