WASHINGTON—A divided federal appeals court on Thursday reaffirmed its ruling last year that isolated human genes can be patented, a victory for the biotechnology industry.

The U.S. Court of Appeals for the Federal Circuit, in a 2-1 ruling, again largely upheld the ability of Myriad Genetics Inc. to obtain patents on two genes that can signal if a woman faces greater risk of developing breast cancer or ovarian cancer. Myriad's patents allow the company to be the exclusive U.S. commercial provider of genetic screenings for the diseases.

Patients and medical groups have argued that Myriad is trying to patent "products of nature," which can't be patented. They say the gene patents interfere with medical treatment and scientific research, claims that Myriad disputes.

This spring, the U.S. Supreme Court ordered the Federal Circuit to reconsider the Myriad case in light of the justices' new ruling in a different patent case that tightened rules on medical-testing patents.

On Thursday, the appeals court said the Supreme Court's ruling didn't change the Federal Circuit's earlier decision.

"Permitting patents on isolated genes does not pre-empt a law of nature," Judge Alan Lourie wrote in the court's lead opinion.

Judge Lourie's opinion reiterated his earlier ruling that the process of extracting and isolating a gene from the human body made the gene chemically distinct from the DNA that exists naturally.