Polymorphisms: Origins and Maintenance


Polymorphism is variation in specific locations in the deoxyribonucleic acid (DNA) sequence. Some authors use the term only for variant alleles with at least 1% frequency in a population. This shows the population dependence of the concept itself. Variation arises initially by some form of mutation in a single individual but, because DNA is transmitted from parent to offspring, over time the frequency and geographical distribution of a genetic variant is essentially a population concept that depends on history.

Keywords: variation; evolution; polymorphism; single nucleotide polymorphism; population genetics

Figure 1.

Schematic tree showing relationships between human geography and genetic distance.



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Further Reading

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Sharp AJ, Cheng Z and Eichler EE (2006) Structural variation of the human genome. Annual Review of Genomics and Human Genetics 7: 407–442.

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Weiss, Kenneth M(Apr 2008) Polymorphisms: Origins and Maintenance. In: eLS. John Wiley & Sons Ltd, Chichester. http://www.els.net [doi: 10.1002/9780470015902.a0005449.pub2]