People who carry a “G” instead of an “A” at a specific spot in their genetic code have roughly a six-fold higher risk of developing certain types of brain tumors, a Mayo Clinic and University of California, San Francisco study has found. The findings, published online in the journal Nature Genetics, could help researchers identify people at risk of developing certain subtypes of gliomas which account for about 20 percent of new brain cancers diagnosed annually in the U.S. and may lead to better surveillance, diagnosis and treatment.

Researchers still have to confirm whether the spot is the source of tumors, but if it’s not, “it is pretty close,” says senior author Robert Jenkins, M.D., Ph.D., a pathologist at the Mayo Clinic Cancer Center. “Based on our findings, we are already starting to think about clinical tests that can tell patients with abnormal brain scans what kind of tumor they have, just by testing their blood.”