Scientists have found a small region on a human chromosome harboring a gene which greatly increases the risk of prostate cancer, said a report in the November 22 issue of science . Once the gene is identified, it could lead to a test to determine if a male in a family with a high incidence of prostate cancer has a mutated version that puts the high risk of the disease.
molecular biologist Jeffrey Trent of the National Center for Human Genome Research (NCHGR) knew he was taking a risk when he and his colleagues at Johns Hopkins University, the University of Michigan and the University of Umeå in Sweden has decided to seek a gene for familial prostate cancer. Cancer is very common - hitting some 340,000 men each year in the US alone - it is estimated that only 3% of cases are caused by an inherited mutation. This makes it difficult to tell if a number of cases in a family are really due to a susceptibility gene or a simple accident. And because prostate cancer usually strikes later in life, families of several generations needed to track the inheritance of a gene are rare.
The team has a database of 2,500 families who seemed to have a higher risk of prostate cancer because they had two or more affected members. The group initially focused on 66 families who had at least three men with prostate cancer. They analyzed the genomes of various members of the family for some 341 DNA markers, looking for any changes that have been consistently inherited with prostate cancer - an indication that the markers are located near a gene susceptibility. Their analysis revealed a marker on the long arm of chromosome 1 that does not seem to travel together with the risk of cancer. Confirmation, and more accurate location of the gene, came when the researchers studied another chromosome 1 markers in their original 66 families, plus another 25.
Because the gene, to be called HPC1 , for hereditary prostate cancer 1, has not yet been cloned, its function is unknown, but there are indications that this could be a cancer-promoting oncogene rather than a tumor suppressor. The research team believes the gene that is involved in homing on about a third of inherited cases of prostate cancer, or about 3% of the total. But the gene may also play a role in prostate cancers that do not run in families. Therefore, says molecular biologist Alfred Knudson of the Fox Chase Cancer Center in Philadelphia, the gene could be a "major contributor" to the risk of prostate cancer.
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