Immune gene linked to prostate cancer. (Cancer).

Scientists analyzing the DNA of families whose men are prone to prostate cancer have found a mutated gene that predisposes them to the disease. It's still unclear how often a mutation in this gene leads to the cancer in men with no family history of the disease, who make up the majority of cases.

The gene encodes a protein that sits on the surface of immune cells called macrophages. Known as a scavenger receptor, the protein binds to a variety of fat-beating molecules and has been previously associated with hardening of the arteries and heart disease.

A 31-member team of researchers led by Jianfeng Xu of Wake Forest University School of Medicine in Winston-Salem, N.C., took a close look at the immune system gene because it's in a chromosomal region that past studies had linked to prostate cancer. Moreover, there has been some evidence that sexually transmitted infections and aberrant macrophage activity predispose men to prostate cancer.

In a study to be reported in an upcoming Nature Genetics, the investigators observed mutations in the macrophage gene in the men with prostate cancer from 13 of the 190 cancer-prone families being studied. As a follow-up, the researchers did a preliminary survey of men without a family history of the disease. They found that the gene is mutated in up to 12.5 percent of men with prostate cancer and up to 1.8 percent of unaffected men.--J.T.