Another promising direction for research is to focus on polymorphisms that are known to be functional. For example, a microarray is now in use that includes 15,000 SNPs that result in a change of an amino acid during translation. Functional polymorphisms are important because they add considerable power in GWA research by testing a direct association between the polymorphism and the trait rather than relying on indirect association via neighbouring polymorphisms. Eventually, individual sequencing will make it possible to examine polymorphisms of any kind. An obvious way to increase power to detect small effects is to increase sample sizes. However, rather than designing a single definitive study to detect associations of very small effect size, it might be necessary to use a series of replication studies to winnow the small kernels of grain from the chaff, side-stepping some of the daunting issues involved in correcting for multiple testing in a single study. Another way to increase power is to use quantitative genetic research to be more precise about how to carve nature at its joints, including gene-gene and gene-environment interactions.
