Chimeric gene
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Chimeric genes (literally, made of parts from different sources) form through the combination of portions of two or more coding sequences to produce new genes. These mutations are distinct from fusion genes which merge whole gene sequences into a single reading frame and often retain their original functions.
Chimeric genes can form through several different means. Many chimeric genes form through errors in DNA replication or DNA repair so that pieces of two different genes are inadvertently combined.[1] Chimeric genes can also form through retrotransposition where a retrotransposon accidentally copies the transcript of a gene and inserts it into the genome in a new location. Depending on where the new retrogene appears, it can recruit new exons to produce a chimeric gene. Chimeric genes can also form through Ectopic recombination, where there is an exchange between portions of the genome that are not actually related. This process occurs often in human genomes, and abnormal chimeras formed by this process are known to cause color blindness. Finally, chimeric symbiogenetic genes (S-genes) are formed by the fusion of gene fragments from endosymbionts, organisms living within the body or cells of another organism.[2] A naturally occurring example of this is a chimeric gene called "Booster", which boosts photosynthesis in poplar trees. It contains fused segments of genetic code from a bacteria which lives in poplar roots, from an ant which farms a fungus which infects poplar, and from chloroplasts in poplar cells.[3][4]