SNP vs. SNV vs. Mutation

BY IN Notes 2 COMMENTS ,

SNP = single nucleotide polymorphism. As its name suggests, a SNP is a DNA change at the single nucleotide level. By virtue of being a polymorphism, a SNP must occur commonly within a population, with “common” typically being understood as having a minor allele frequency of >1%. The commonality of SNPs generally implies that SNPs do not cause deleterious affects on downstream protein products or other functions and thus was able to become fixed in a population.

SNV = single nucleotide variation. Again, as its name suggests, a SNV is also a DNA change at the single nucleotide level. Unlike SNPs, SNVs do not have to occur commonly within a population. The term ‘SNV’ is sometimes used interchangeably with ‘somatic point mutation.’

A mutation is a much larger class of DNA and RNA sequence changes. Mutations encompass
– germline as well as somatic changes
– non-synonymous as well as synonymous changes
– point mutations, insertions, and deletions (both short and long chromosomal regions)
– chromosomal amplifications and loss of heterozygosity
– etc
SNPs and SNVs are types of mutations.

2 Comments

  1. John Iodice |

    “Mutation” is being used here as a synonym for “polymorphism”. But this is really a secondary meaning, isn’t it? Its primary meaning is the copying error that first gives rise to a polymorphism. If the new sequence is then copied faithfully (such as in subsequent generations), then the copies also contain the polymorphism, but calling that accurate copy a “mutation” is . . . what? An alternate usage? A metaphor? Wrong?

    Reply
    • Jean |

      No, “mutation” is not being used here as a synonym for “polymorphism” or SNP as explained in the post: a polymorphism is a type of mutation, specifically a common, generally non-deleterious nucleotide change. However, I think I see your point. By “mutation”, I mean the nucleotide change; I do not mean the copying error that gave rise to the nucleotide change. If you want to reserve ‘mutation’ to refer to the copying error, perhaps ‘mutant allele’ would be a more appropriate term for the nucleotide change.

      Reply

So, what do you think ?