Gene copy number

The gene copy number (also "copy number variants" or CNVs) is the number of copies of a particular gene in the genotype of an individual. Recent evidence shows that the gene copy number can be elevated in cancer cells. For instance, the EGFR copy number can be higher than normal in Non-small cell lung cancer.

In certain cases, such as rapidly growing Escherichia coli cells, the gene copy number can be 4-fold greater for genes located near the origin of DNA replication, rather than at the terminus of DNA replication. Elevating the gene copy number of a particular gene can increase the expression of the protein that it encodes.

Sources and notes

• Iafrate A, et al. (2004) Detection of large-scale variation in the human genome. Nat Genet 36: 949-51
• Sebat J, et al. (2004) Large-scale copy number polymorphism in the human genome. Science 305: 525-528
• Cappuzzo F, Hirsch, et al. (2005) Epidermal growth factor receptor gene and protein and gefitinib sensitivity in non-small-cell lung cancer. J Natl Cancer Inst 97: 643–655
• Atkinson M, Savageau M, Myers JT, Ninfa A (2003) Development of Genetic Circuitry Exhibiting Toggle Switch Behavior in Escherichia Coli. Cell 113: 601
• Freeman, JL, et al (2006) Copy number variation: New insights into genome diversity. Genome Res 2006; 16: 949-61.

Further reading

• Genome-wide analysis of DNA copy-number changes using cDNA microarrays "Gene amplifications and deletions frequently contribute to tumorigenesis. Characterization of these DNA copy-number changes is important for both the basic understanding of cancer and its diagnosis."
• New Scientist article Human DNA is far more varied than thought published November 22, 2006 "Two separate studies of the human genome have revealed an unsuspected amount of variation between people in the number of copies of genes they have. [...] They discovered that nearly 24 million nucleotides are involved in such copy number variants (CNVs). [...] They found 1447 CNVs, covering about 12% of the human genome."
• National Geographic article "DNA varies more widely from person to person, Genetic maps reveal" published Novermber 22, 2006