With the widespread application of highly parallel SNP genotyping arrays much of the recent effort in human genetics has focused on defining the role of genetic variation in disease and physical traits. A small subset of this work, however, has attempted to examine the more proximal effects of genetic variation on mRNA and protein levels [1]–[5]. This has the potential to inform on several levels; first, it is a critical step toward understanding the pathobiological consequences of genetic variants linked to disease; second, it affords the opportunity to form inferences regarding relationships between genes based on patterns of co-regulation; and third, it provides a more complete view of multiple levels of regulation of gene expression than that provided by the traditional reductionist method [6], [7].
