Snapping up SNPs.

Single nucleotide polymorphisms (SNPs) are a hot item in current discussions about the practical applications of genomics and Human Genome Project research. SNPs are simply DNA point mutations—single base-pair changes or insertion/deletions—that are present at measurable frequencies in the population. SNPs are the most common variations in the human genome; the current estimate is that SNPs occur once every 100–300 bp. SNPs exist at defined positions within genomes (sequence tagged sites [STS]) and can be used for gene mapping, defining population structure and performing functional studies. SNPs are expected to greatly facilitate large-scale genetic studies concerned with determining linkage between sequence variations and heritable phenotypes. SNPs might also become an efficient tool for genetic identification for legal and forensic applications.