If the concept of personalized medicine is to be realized, it is increasingly clear that single nucleotide polymorphisms (SNPs), the most common genetic variations between human beings, will be a key enabler. A SNP is a single base-pair mutation that occurs at a specific site in the DNA sequence. To classify a variation as a SNP it should occur in at least 1% of the population.
Since it is SNPs that are responsible for over 80% of the variation between two individuals, they are ideal for the task of hunting for correlations between genotype and phenotype. As some SNPs predispose individuals to have a certain disease or trait or react to a drug in a different way, they will be highly useful in diagnostics and drug development.