Single-nucleotide polymorphism

In genetics, a single-nucleotide polymorphism (SNP /snɪp/; plural SNPs /snɪps/) is a germline substitution of a single nucleotide at a specific position in the genome. Although certain definitions require the substitution to be present in a sufficiently large fraction of the population (e.g. 1% or more), many publications do not apply such a frequency threshold.