WASHINGTON -- U.S. scientists announced Sunday that they have identified a gene linked to an inherited form of prostate cancer -- a breakthrough that could significantly advance efforts to combat the deadly disease.

More than 189,000 cases of prostate cancer are diagnosed in the United States each year, which makes it likely that 16 percent of adult males will develop prostate cancer some time during their lifetime, according to U.S. health officials.

It is believed about nine percent of them have hereditary origins.

The discovery, made by a group of researchers from the National Human Genome Research Institute, Johns Hopkins medical institutes and the Cleveland Clinic among others, is expected to eventually help doctors find a way to neutralize the gene's dangerous role.

"The new finding presents a tantalizing clue about the workings of the complex genetic machinery that leads to this common cancer," said Dr Jeffrey Trent, a leading researcher on the project.

The hunt for the gene has been underway since 1992, when Johns Hopkins scientists first showed that some forms of prostate cancer could be inherited.

In 1996, after studying 91 high-risk prostate cancer families, the researchers identified a region of Chromosome 1 where prostate cancer can appear and named the Hereditary Prostate Cancer 1 region (HPC1).

Since then, scientists have mapped prostate cancer susceptible genes to two other parts of Chromosome 1, as well as to chromosomes 17, 20 and x.

The specific cancer-associated gene, discovered in the HPC1 region and dubbed Ribonuclease l, normally plays the role of a watchdog, defending cells from viruses and making sure they remain healthy, according to the study that appears in the February issue of ***** Nature Genetics ****.

If healthy, it sends signals to a cell, which is about to become cancerous, and the cell kills itself to protect the rest of the body.

But an inherited defective Ribonuclease l can lose this ability, thus allowing cancerous cells to multiply.

This cellular self-destruct mechanism might be made inactive through genetic mutation, which could explain why some prostate cells become cancerous, the scientists said.

However, mutations of one gene will not be enough to explain all forms of inherited prostate cancer, according to Doctor John Carpten, the leader of the research team.

"This is not the only gene involved in prostate cancer," he cautioned. "We know that mutations in any number of genes can lead to the development of prostate cancer, and this gene possibly represents a new member in the repertoire of prostate cancer genes."

Not is the discovery expected to immediately result in new diagnostic tests and treatments.

But the authors of the study said their findings create new opportunities for better understanding prostate cancer.

"We expect that there will be multiple genes involved in prostate cancer," Trent argued. "And as we identify them, we should be able to put together a picture of the factors that convert a normal prostate into the most common cancer in men." 10-02-11.J01