Genetic clues to prostate cancer

Three teams of scientists have uncovered a number of genetic variants, which can powerfully predict a carrier's risk of developing prostate cancer. One team based jointly at the University Of California and Harvard Medical School, one from the US National Institutes of Health and an Icelandic Company, deCODE genetics, have uncovered seven SNPs, which predict more than a fivefold range of risk for prostate cancer. All the studies have been published early online by the journal Nature Genetics.

SNPs are DNA sequence variations occurring when a single nucleotide - A, T, C, or G - at a specific location in the genome differs between individuals (or between paired chromosomes in an individual). It's the first glimpse into the genetic basis of a disease, which, despite intense research, has remained stoically enigmatic. 'It gives us the first real insight we've had into the cause of prostate cancer and how we might do something about it', said Dr Brian Henderson, dean of the Keck School of Medicine at the University of Southern California.

Research has become focused on a small region of chromosome 8, which contains all of the variants. Intriguingly, all of the SNPs lie outside of the coding region of any genes, in a region previously written off as 'junk' DNA. This region, therefore, holds the secret of a potentially novel mechanism for non-coding sequence variation to alter the risk of disease.

The high risk variants are found at a much higher frequency in African American men, which may go some way to explaining the fact that they are twice as likely to die from there disease compared to other ethnic groups. 'The disease's greater prevalence among African Americans had hinted at some sort of a genetic basis for it', said Henderson, adding 'and our findings here, in this study, suggest that a large fraction of the disparity between African Americans and other populations could be due to genetic variation in this region'.

The studies have the potential to form the basis of a predictive genetic test, that could be used to siphon high-risk men into a more rigorous screening for the early signs of prostate cancer. Despite being the second largest cause of male death in Britain, mortality rates are falling due to improved screening. 'Clinical testing of these genetic variants may help us identify men who should be prioritised for early prostate cancer screening and prevention efforts', said David Reich, an assistant professor of genetics at Harvard Medical School.