Anyone in the United States who wants to know if she has mutations in two breast cancer genes has little choice of where to be tested. One company alone has patents on the genes, and that company pretty much controls the market.

On Monday, the Supreme Court will take up the issue of whether companies can own patents on genes. But there is another issue, often overlooked, that might make the patent question beside the point. No matter which way the patent decision goes, the company, Myriad Genetics, will still own the largest database that tells patients what various mutations mean.

With 17 years of experience, millions of tests looking for thousands of mutations in the genes, and a $500 million investment, the company was able to amass a huge database that tells which DNA changes increase cancer risk and by how much, and which are inconsequential blips in DNA. And it is keeping that data to itself.

Some genetics researchers are furious and have now figured out a way to get the data anyway. Every time Myriad sends out a report on a gene test, it specifies not just the mutations it found but also what they mean. As a result, Myriad’s data on each of the mutations is scattered in millions of reports in the hands of doctors and patients. If the geneticists could just gather those reports, they say, they can recreate Myriad’s database.