- Frameshift mutation
A frameshift mutation (also called a framing error) is a genetic
mutation caused byindel s, ie. insertion or deletion of a number ofnucleotide s that is not evenly divisible by three from aDNA sequence. Due to the triplet nature ofgene expression bycodon s, the insertion or deletion can disrupt thereading frame , or the grouping of the codons, resulting in a completely different translation from the original. The earlier in the sequence the deletion or insertion occurs, the more altered the protein produced is.A
frameshift mutation causes the reading of codons to be different, so all codons after the mutation (with a few exceptions due to redundancy) will code for different amino acids. Furthermore, the stop codon "UAA, UGA, or UAG" will not be read, or a stop codon could be created at an earlier or later site. The protein being created could be abnormally short, abnormally long, and/or contain the wrong amino acids. It will most likely not be functional.Frameshift mutations frequently result in severe genetic diseases such as Tay-Sachs disease. A frameshift mutation is responsible for the disabling of the
CCR5 HIV receptor and some types of familialhypercholesterolemia (Lewis, 2005, p. 227-228). Frameshift mutations can also be beneficial.Frameshifting may also occur during protein translation, producing different proteins from overlapping open reading frames, such as the gag-pol-env retroviral proteins. This is fairly common in viruses and also occurs in bacteria and yeast (Farabaugh, 1996).
ee also
Frameshift References
*Farabaugh, P. J. 1996. Programmed translational frameshifting. Microbiol. Rev. 60:103-4.
*Lewis, R. 2005. "Human Genetics: Concepts and Applications", 6th Ed. McGraw Hill, New York.External links
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