Prostate Cancer and SNPs

SNPs are single nucleotide polymorphisms, simple the single base has been replaces by another somewhere in the DNA and this results in a higher predilection to PCa. In a recent Nature Genetics paper the authors state:

More than 70 prostate cancer susceptibility loci, explaining ~30% of the familial risk for this disease, have now been identified. On the basis of combined risks conferred by the new and previously known risk loci, the top 1% of the risk distribution has a 4.7-fold higher risk than the average of the population being profiled. These results will facilitate population risk stratification for clinical studies.

These are germ line mutations and given the germ-line predisposition ones risk is increased substantially. They continue:

Epidemiological studies provide strong evidence for genetic predisposition to prostate cancer. Most susceptibility loci identified thus far are common, low-penetrance variants found through genome-wide association studies. Fifty-four loci have been identified so far.

Finally they state:

With the identification of these new loci, 77 susceptibility loci for prostate cancer have now been identified. On the basis of an overall twofold familial relative risk for the first-degree relatives of prostate cancer cases and on the assumption that SNPs combine multiplicatively, the new loci reported here, together with those already known, explain approximately 30% of the familial risk of prostate cancer. Taking into consideration these SNPs and this risk model, the top 1% of men in the highest risk stratum have a 4.7-fold greater risk relative to the population average, and the top 10% of men have a 2.7-fold greater risk.

What does this mean for health care. Is is prognostic and if so why? One of the problems with SNPs is that the pathways they control are not clear. SNPs just sit there and we know that if they are there then the risk is greater. The lingering question is still what do they really do?