NEW YORK (AP) — Scientists say they've identified the first genetic mutation with a major effect on the risk of prostate cancer that runs in families and strikes men early, by age 55.

The mutation accounts for only about one percent of all prostate cancers.  But studying it might help scientists understand the disease in general and find better treatments.   

More than 240,000 men are expected to be diagnosed with prostate cancer in the United States this year. Most cases are sporadic, rather than inherited, and on average they are diagnosed around age 70.

The work is reported in of the New England Journal of Medicine.

 The researchers said inheriting the mutation raises the risk of prostate cancer by 10 times or more.

New England Journal of Medicine: