Local extension (LE) adds functionally associated genes to increase the overlap between two gene sets. (a) Local extension is particularly useful when a weakly significant overlap between a query gene set and a known functional set is detected by a classic enrichment method. (b) The positions of the genes in a global functional network are consulted. (c) Close network neighbors are added to one set, and the significance of the newly formed overlap is re-calculated.
Wang et al. Genome Biology 2012 13:R125 doi:10.1186/gb-2012-13-12-r125