single nucleotide polymorphism
(... NOO-klee-oh-TIDE PAH-lee-MOR-fih-zum)
The most common type of change in DNA (molecules inside cells that carry genetic information). Single nucleotide polymorphisms occur when a single nucleotide (building block of DNA) is replaced with another. These changes may cause disease, and may affect how a person reacts to bacteria, viruses, drugs, and other substances. Also called SNP.
DNA sequence variations that occur when a single nucleotide (adenine, thymine, cytosine, or guanine) in the genome sequence is altered; usually present in at least 1% of the population; pronounced "snip". Also called SNP.