In order to define and characterize a biosynthetic gene cluster, all the putative genes within said cluster must first be identified and their functions must be characterized. This can be performed by complementation and knock out experiments. In the process of characterizing putative genes, the genome under study becomes increasingly well understood as more interactions can be identified. Identification of putative genes is necessary to study genomic evolution, as significant proportion of genomes make up larger families of related genes. Genomic evolution occurs by processes such as duplication of individual genes, genome segments, or entire genomes. These processes can result in loss of function, altered function, or gain of function, and have drastic affects on the phenotype.
DNA mutations outside of a putative gene can act by positional effect, in which they alter the gene expression. These alterations leave the transcription unit and promoter of the gene intact, but may involve distal promoters, enhancer/silencer elements, or the local chromatin environment. These mutations can be associated with diseases or disorders associated with the gene.<br />