Source:http://linkedlifedata.com/resource/umls/id/C1710091
NCI: Single Nucleotide Polymorphism in Intergenic Sequences consists of a variation at an appreciable frequency between individuals of a single interbreeding population of a single nucleotide, due to base substitution, at an equivalent location within a DNA sequence of genetic material that lies between the boundaries of adjacent genes. SNPs occur, on average, once every 1000 bases and can be used in gene mapping and linkage analysis.