The emergence of biobanks: practical design considerations for large population-based studies of gene-environment interactions.

The completion of the human genome project has spurred new thinking about launching large-scale cohort studies; as proposed, these studies will differ from past large-scale cohort studies and will focus primarily on how genetic variation interacts with environmental exposures to affect the risk for common human diseases. There is no single 'best design' for large-scale studies of gene-environment interactions. Some studies are best performed in cohort studies where unbiased information can be collected on individuals years before disease onset. Other studies may be most efficiently done with a case-control design using currently available automated data. Population-based biobanks with nested case-control or case-cohort studies offer distinct advantages to some of the resource-intensive large-scale cohort studies under consideration, and may be more acceptable to many of the countries around the world currently considering such projects.