Gene redundancy

Gene redundancy is the existence of multiple genes in the genome of an organism that perform the same function. Gene redundancy can result from gene duplication.^[1] Such duplication events are responsible for many sets of paralogous genes.^[1] When an individual gene in such a set is disrupted by mutation or targeted knockout, there can be little effect on phenotype as a result of gene redundancy, whereas the effect is large for the knockout of a gene with only one copy.^[2] Gene knockout is a method utilized in some studies aiming to characterize the maintenance and fitness effects functional overlap.^[3]

Classical models of maintenance propose that duplicated genes may be conserved to various extents in genomes due to their ability to compensate for deleterious loss of function mutations.^[4][5] These classical models do not take into account the potential impact of positive selection. Beyond these classical models, researchers continue to explore the mechanisms by which redundant genes are maintained and evolve.^[6][7][8] Gene redundancy has long been appreciated as a source of novel gene origination;^[8] that is, new genes may arise when selective pressure exists on the duplicate, while the original gene is maintained to perform the original function, as proposed by newer models^[4].