gene amplification


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Gene amplification

The process by which a cell specifically increases the copy number of a particular gene to a greater extent than it increases the copy number of genes composing the remainder of the genome (all the genes which make up the genetic machinery of an organism). It is therefore distinguished from duplication, which is a precise doubling of the genome preparatory to cell division, and endoreduplication, which leads to endopolyploidy.

Gene amplification results from the repeated replication of the deoxyribonucleic acid (DNA) in a limited portion of the genome, in the absence of or to a much greater extent than replication of DNA composing the remainder of the genome. Thus is formed a cell in which the genes composing a limited portion of the genome are present in relatively high copy number, while the genes composing the remainder of the genome are present in approximately normal copy number. See Deoxyribonucleic acid (DNA)

Since gene amplification increases the copy number of a specific region of the genome without altering the copy number of genes composing the remainder of the genome, it would appear to offer an alternative method for developmental control of gene expression. By increasing the number of copies of a particular gene, the number of gene copies available for transcription could thereby be increased.

In a number of instances of gene amplification, the amplification phenomenon appears to be developmentally regulated, and the amplified copies of the gene are subsequently lost from the cell. Studies on cells in culture have demonstrated “amplification” of genes involved in resistance to specific drugs. See Gene, Gene action

gene amplification

[′jēn ‚am·plə·fə‚kā·shən]
(cell and molecular biology)
Any process by which a deoxyribonucleic acid sequence is disproportionately duplicated in comparison with the parent genome.
(genetics)
Repeated replication in a single cell cycle of the deoxyribonucleic acid (DNA) in a limited portion of the genome, resulting in an increase in the number of copies of a particular gene or DNA segment.
References in periodicals archive ?
Epidermal growth factor receptor gene amplification and gefitinib sensitivity in patients with recurrent lung cancer.
There were only 2 cases in the equivocal category (score 2+), and both showed gene amplification (Table 2).
HER2 testing in patients with breast cancer: poor correlation between weak positivity by immunohistochemistry and gene amplification by fluorescence in situ hybridization.
Of these, 6 were progressing on anti-HER2 agents at the time of blood sampling, and 4 had ERBB2 gene amplification in cfDNA, whereas 3 patients who were responding to their treatment had no evidence of ERBB2 gene amplification in cfDNA (Table 1).
Glutaredoxin gene amplification was done by PCR by adding appropriate primers and maintaining amplification temperature.
Keywords: Epidermal growth factor, Gene amplification, High pressure liquid chromatography.
HER2 gene amplification is associated with shorter disease-free and overall survival in breast cancer.
Ensure that at least one tumor sample is tested for either HER2 protein expression (immunohistochemistry [IHC] assay) or (in situ hybridization [ISH assay]) for HER2 gene amplification.
In the newly reported study, the Resar team applied the same techniques to several strains of human breast cancer cells in the laboratory, including the so-called triple negative cells - those that lack hormone receptors or HER2 gene amplification.
Bacteria with this gene were then cultivated on growth substrate lacking both amino acids, which led to the selection for gene amplification resulting in up to 20 copies of the same gene.