single nucleotide polymorphism

noun

: snp

Although all humans share 99.9 percent of their genetic material, single-letter differences in our DNA sequences—known as single nucleotide polymorphisms, or SNPs ("snips")—ensure that each individual is unique.

—Alison McCook, Scientific American

In DNA dialect, if the nucleotide letter T appears instead of C, or G where usually there's A, the gene is said to contain a single nucleotide polymorphism.

—Jeff Wheelwright, Discover