In June the U.S. Supreme Court ruled that patents on genes were invalid. Yet corporate intellectual-property claims can still harm patients.

The court struck down patents held by Myriad Genetics on two human genes linked to breast and ovarian cancers, BRCA1 and BRCA2. The decision ended the company’s U.S. monopoly on testing those two genes for cancer-related mutations. But Myriad is now using a different tactic that restricts patient choice around genetic testing. The company has constructed a database of the genetic variants found in people who took its BRCA test. That unparalleled record of the natural variation in these important genes—collected from patients—is claimed to be Myriad’s own intellectual property.

Doctors can’t assess the significance of gene variants they find in their patients without free exchange of the kind of information held in Myriad’s database. It is as if patients’ radiological images were all examined by a single company that didn’t give the medical community a chance to learn from them.

Myriad’s database prevents patients from easily getting second opinions when they receive diagnoses based on BRCA tests. Patients need to be able to seek confirmation that the gene variant they have really does mean what the testing laboratory says it means. That can’t happen if Myriad is the only one with the data.

Late last year, I launched a grass-roots effort bringing doctors and patients together to free valuable data from BRCA1 and BRCA2 test reports. Colleagues of mine who see patients at cancer clinics now place copies of these reports—with identifying details removed—in an existing public database called ClinVar, which is run by the National Institutes of Health. This project, called Sharing Clinical Reports, has now made more than 6,000 reports accessible. Efforts to enlist coöperation from clinics around the country should free up tens of thousands more reports soon.

The medical community has condemned private databases that limit the dissemination of medical knowledge. The American Medical Association adopted a resolution in 2009 stating: “The use of patents, trade secrets, confidentiality agreements, or other means to limit the availability of medical procedures places significant limitation on the dissemination of medical knowledge, and is therefore unethical.” A newer resolution, in June, calls for the release of all information generated by testing for genetic variants, with appropriate privacy protections. We’re still far from seeing that come to pass. The medical community must prevent intellectual-property claims from being used to monopolize such vital data.

Robert Nussbaum is chief of the Division of Genomic Medicine at the University of California, San Francisco, and worked on the legal challenge to Myriad’s gene patents.