Extracting meaning from functional genomics experiments.

The completion of draft genome sequences for human, mouse, rat, and an increasing number of other species, has provided us with preliminary gene catalogues for many organisms of medical and scientific interests. Interpreting these gene lists in the context of the organism's underlying biology, however, remains difficult. The development of DNA microarrays provided one potential source of data to help interpret gene function; by profiling global patterns of gene expression across diverse conditions, it was hoped that we might be able to develop insight into biological function. But the power of these functional genomics assays, as well as assays in proteomics and metabolomics, is that they primarily give us lists of differentially expressed genes that can be correlated with particular phenotypic states, but which remain difficult to link mechanistically to the biology driving the phenotype.