A variation in the base sequence occurring at any given single position in the genome (for example A instead of C) that is found in more than 1% of the population. It thus differs from a point mutation only in its greater frequency. SNPs can be found in all parts of the genome, including structural genes, regulatory regions, and noncoding DNA. In the human genome overall, about 10 million SNPs are thought to occur, making them exceptionally useful as molecular markers. Some are known to be linked to disease-causing alleles. They can be detected by various techniques, including RNA sequencing, polymerase chain reaction, or microarrays. See international hapmap project.