Copy number variation

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 (CNV) is a phenomenon in which sections of the genome are repeated and the number of repeats in the genome varies between individuals.[1] Copy number variation is a type of structural variation: specifically, it is a type of duplication or deletion event that affects a considerable number of base pairs.[2] Approximately two-thirds of the entire human genome may be composed of repeats[3] and 4.8–9.5% of the human genome can be classified as copy number variations.[4] 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 dinucleotide repeats (two repeating nucleotides e.g. A-C-A-C-A-C...) and trinucleotide 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,[5] hence the likely effects of these repeats on phenotype.

  1. ^ a b McCarroll SA, Altshuler DM (July 2007). "Copy-number variation and association studies of human disease". Nature Genetics. 39 (7 Suppl): S37-42. doi:10.1038/ng2080. PMID 17597780. S2CID 8521333.
  2. ^ Sharp AJ, Locke DP, McGrath SD, Cheng Z, Bailey JA, Vallente RU, et al. (July 2005). "Segmental duplications and copy-number variation in the human genome". American Journal of Human Genetics. 77 (1): 78–88. doi:10.1086/431652. PMC 1226196. PMID 15918152.
  3. ^ de Koning AP, Gu W, Castoe TA, Batzer MA, Pollock DD (December 2011). "Repetitive elements may comprise over two-thirds of the human genome". PLOS Genetics. 7 (12): e1002384. doi:10.1371/journal.pgen.1002384. PMC 3228813. PMID 22144907.
  4. ^ Zarrei M, MacDonald JR, Merico D, Scherer SW (March 2015). "A copy number variation map of the human genome". Nature Reviews. Genetics. 16 (3): 172–83. doi:10.1038/nrg3871. hdl:2027.42/146425. PMID 25645873. S2CID 19697843.
  5. ^ Hastings PJ, Lupski JR, Rosenberg SM, Ira G (August 2009). "Mechanisms of change in gene copy number". Nature Reviews. Genetics. 10 (8): 551–64. doi:10.1038/nrg2593. PMC 2864001. PMID 19597530.