Association of common variants to diseases is still in a phase of rapid discovery. One immediate consequence is that the relative risk for an individual, predicted from very partial information, can change rapidly as more information is added. For example, three of the 18 risk predictions have changed in my profile on the deCODEme site since November:

Restless legs syndrome: OR 1.94>0.97, was 1, now 4 SNPs
Prostate cancer: OR 1.05>0.77, was 5, now 8 SNPs
Type 2 diabetes: OR 1.45>1.10, still 8 SNPs

In the first two cases, the new information is the association of new variants that can be added to the risk calculation. In the third case I do not know if this is a recalculation or the result of more studies on the same 8 SNPs. I’ll make a rash prediction and be prepared to be proven wrong, but I think the more common variants are added, the more instances of (individual, disease) will tend to OR=1.0. Maybe I am just indulging in the fallacy called “the law of averages”, but it is at least a conservative, testable hypothesis.

Full genotypes are now available for download, so the project is about to become interesting.