NEW YORK (AP) _ Scientists have identified a second faulty gene that appears to make some families prone to developing prostate cancer, a finding that someday might help doctors diagnose and treat some cases of the disease.
Only about 9 percent of prostate cancer cases are hereditary, and the gene is related to only an unknown fraction of these. It's not clear whether the gene, called RNASEL (pronounced ``R-N-ace-L''), plays any role in nonhereditary cancers.
The new work appears in the February issue of the journal Nature Genetics. The previously identified gene linked to hereditary prostate cancer, called HPC2-ELAC2, also appears to be implicated in only a small fraction of cases.
The new study was done by a consortium of researchers from institutions including the National Human Genome Research Institute in Bethesda, Md., the Johns Hopkins Medical Institutions in Baltimore and the Cleveland Clinic.
Further study of the gene could help shed light on the biology of prostate cancer which might give hints for developing new treatments.
In its normal form, the RNASEL gene was previously known to make cells commit suicide under some conditions, and that might explain the cancer connection, said study co-author Robert Silverman of the Cleveland Clinic.
One reason for a cell to kill itself is that it's on the road to becoming cancerous. If the RNASEL gene is defective and can't send its suicide signal, it loses its ability to act like a brake on the disease, Silverman said.
Jeffrey Trent of the genome research institute, senior author of the paper, said defective versions of the gene might also make prostate cancer more aggressive.
Scientists screened DNA from 26 families prone to prostate cancer and found two families in which brothers with the disease had inherited mutated copies of RNASEL. Such inherited mutations were uncommon in the general population, the researchers found.
Timothy Rebbeck, who studies prostate cancer genetics at the University of Pennsylvania but didn't participate in the new study, called the work exciting because RNASEL is only the second known gene to be implicated in hereditary prostate cancer.
While it appears responsible for only a tiny fraction of prostate cancers, he said, that's probably the case for any inherited defect that promotes the disease.