Single Nucleotide Polymorphism (SNP)


A single nucleotide polymorphism (SNP) is an abundant form of genome sequence variation comprising single base pair alternatives represented at a population frequency of more than 1%. SNPs contribute greatly to the genetic basis of phenotypic variation in ways yet to be fully understood.

Keywords: genome; variation; polymorphism; allele; haplotype

Figure 1.

Observed levels of nucleotide diversity (π) in and around human genes. A simple two‐exon gene is represented in genomic DNA and processed messenger RNA (mRNA) forms, with various subdomains (including degeneracy classes of coding nucleotides) marked to illustrate the typically observed levels of sequence variation reported across a range of publications. There is, however, a disparity in sequence variability of well over 10‐fold between different genes and chromosomal regions. cDNA: complementary DNA; UTR: untranslated region; CDS: coding sequence.



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Further Reading

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How to Cite close
Brookes, Anthony J(Dec 2007) Single Nucleotide Polymorphism (SNP). In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0005006.pub2]