Researchers at Johns Hopkins and the University of Michigan have discovered an inherited mutation linked to significantly higher risk of prostate cancer development at a younger age.

The discovery, after two decades of looking, provides insight into the disease development. And though those with the mutation comprise just a fraction of the 240,000 new cases diagnosed annually, the discovery could also help doctors determine who needs earlier screening.

The discovery is the first major genetic variant found for inherited prostate cancer, said Dr. Kathleen A. Cooney, professor of internal medicine and urology at the Michigan Medical School and a senior author of the study, which was published in the New England Journal of Medicine.

The study found that those with a family history of prostate cancer were much more likely to have the mutation, and that gave them a 10-20 percent higher risk of developing the disease themselves. All those in the study who already had the disease also had the mutation.

“It’s long been clear that prostate cancer can run in families, but pinpointing the underlying genetic basis has been challenging and previous studies have provided inconsistent results,” said William B. Isaacs, professor of urology and oncology in Hopkins School of Medicine and the study’s other senior author.

The researchers say further study is needed but it may be possible to develop a genetic test for inherited prostate cancer, like the one for BRCA1 and BRCA2 mutations that increase a woman’s change of developing breast and ovarian cancer.