A single-nucleotide polymorphism is variation at one nucleotide position in sampled genomes. Under an infinite sites mutation model, the number of such variable positions in a sample equals the number of mutations on the genealogy below its most recent common ancestor.
A tag SNP represents other nearby single-nucleotide polymorphisms whose alleles are strongly correlated through linkage disequilibrium. Tagging reduces the number of markers needed for association mapping; it does not establish that the tag itself causes the phenotype.
// Target: biology.bigb
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Single-nucleotide polymorphism (SNP) is a variation at a single position in a DNA sequence among individuals. In other words, it's a change in a single nucleotide—the building blocks of DNA (adenine [A], cytosine [C], guanine [G], or thymine [T])—that can occur in the genome. SNPs can manifest in several ways, typically as a substitution of one nucleotide for another.
