Copy number variation

From Metapedia
Jump to: navigation, search
This gene duplication has created a copy-number variation. The chromosome now has two copies of this section of DNA, rather than one.

Copy number variation (CNVs) is a relatively new field in genomics and it is defined as a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals in the human population.[1] Copy number variation is a type of structural variation, specifically, it is a type of duplication event that affects a considerable number of base pairs.[2] However, note that although modern genomics research is mostly focused on human genomes, copy number variations also occur in a variety of other organisms including E. coli.[3] Recent research indicates that approximately two thirds of the entire human genome is composed of repeats[4] and 4.8-9.5% of the human genome can be classified as copy number variations.[5] In mammals, copy number variations play an important role in generating necessary variation in the population as well as disease phenotype.[1]

Copy number variations can be generally categorized into two main groups: short repeats and long repeats. However, there are no clear boundaries between the two groups and the classification depends on the nature of the loci of interest. Short repeats include mainly bi-nucleotide repeats (two repeating nucleotides e.g A-B-A-B-A-B…) and tri-nucleotide repeats. Long repeats include repeats of entire genes. This classification based on size of the repeat is the most obvious type of classification as size is an important factor in examining the types of mechanisms that most likely gave rise to the repeats,[6] hence the likely effects of these repeats on phenotype.


References

  1. 1.0 1.1 (2007) "Copy-number variation and association studies of human diseases". Nature Genetics 39: 37–42. doi:10.1038/ng2080. PMID 17597780.
  2. (2005) "Segmental Duplications and Copy-Number Variation in the Human Genome". The American Journal of Human Genetics 77 (1): 78–88. doi:10.1086/431652. PMID 15918152.
  3. (2010) "Quantifying E. coli Proteome and Transcriptome with Single-Molecule Sensitivity in Single Cells". Science 329 (5991): 533–538. doi:10.1126/science.1188308.
  4. (2011) "Repetitive Elements May Comprise Over Two-Thirds of the Human Genome". PLOS Genetics 7 (12): e1002384. doi:10.1371/journal.pgen.1002384. PMID 22144907.
  5. (2015) "A copy number variation map of the human genome". Nature Reviews Genetics 16: 172–183. doi:10.1038/nrg3871. PMID 25645873.
  6. (2009) "Mechanisms of change in gene copy number". Nature Reviews Genetics 10: 551–564. doi:10.1038/nrg2593. PMID 19597530.
Part of this article consists of modified text from Wikipedia, and the article is therefore licensed under GFDL.