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
SNPs and SNVs are types of mutations.