Investigating gene-environment interaction in complex diseases: increasing power by selective sampling for environmental exposure

Background The often limited influence of disease associated alleles on the vulnerability to complex diseases has lead to increased interest in environmental interaction with genotype. However, gene environmental interactions (GEIs) are not easily studied, since high numbers of subjects are required to detect GEI. Methods and results This study provides a potential useful method to increase the power of such studies through selective sampling for environmental exposure. We show that selecting the top and bottom 10% regarding environmental exposure can lead to a 70% reduction in the required number of subjects for genotyping. Conclusion This study demonstrates the potential usefulness of selective sampling in the study of the interplay between genes and environment. The reduction of required subjects can be particularly advantageous in studies where genotyping is extensive, such as in whole genome screens or in studies where phenotyping is expensive.