Scientists say they've found the approximate hiding place of another gene that can give men an inherited tendency toward prostate cancer.

The researchers reported in 1996 that one such gene appears to be lurking on chromosome 1. They are still looking for that one, but now they have found evidence that a second vulnerability gene lies somewhere within a particular region of the X chromosome.That would explain the long-standing observation that a man runs a higher risk of prostate cancer if he has a brother with the disease than a father with it. Only the mother passes on the X chromosome in males, so any susceptibility gene it contains could be inherited by two brothers but not pass from father to son.

About 10 percent of prostate cancers are blamed on an inherited vulnerability. The apparent gene on the X chromosome might explain 15 percent to 20 percent of hereditary cases, researchers said.

The work was presented in the October issue of the journal Nature Genetics by five teams of researchers in the United States, Finland and Sweden. They include William Isaacs of the Johns Hopkins Medical Institutions in Baltimore and Jeffrey Trent, chief of the cancer genetics branch at the National Human Genome Research Institute in Bethesda, Md.