A disease module. (a) Conceptual model of how disease-associated genes (blue nodes), identified by high-throughput analysis, tend to co-localize in the human protein-protein interaction network (white nodes), forming a module (blue oval). The genes in the module are assumed to be more important for the disease than extramodular genes. (b) An actual disease module from allergic patients, showing extracellular proteins that were putatively co-regulated with IL13. Blue nodes are associated with cytokine activity, purple nodes are associated with hormone activity, and orange nodes are associated with growth factor activity according to Gene Ontology Molecular Function. The diagram in (b) is reproduced, with permission, from Bruhn et al. Science Translational Medicine 2014 .