Measuring cis-acting regulatory variants genome-wide: new insights into expression genetics and disease susceptibility

Regulatory polymorphisms have emerged as a prevalent source of phenotypic variability, capable of driving rapid evolution. mRNA profiling combined with genome-wide genotyping of polymorphisms has revealed pervasive genetic influences on gene expression, acting both in cis and in trans. Measuring allelic ratios of RNA transcripts makes it possible to focus on cis-acting factors separately from trans-acting processes. Using large-scale allelic expression analysis, a recent study by Ge and colleagues demonstrates a high incidence of cis-acting regulatory variants, promising insights into the 'missing heritability' component of complex disorders. Here, I evaluate their results and discuss the limitations of the current approach and avenues for exploring disease risk, guiding successful therapy, early intervention, and prevention.