SNP variations

SNPs stand for single nucleotide polymorphisms. These are variations in the DNA sequence that involve an alteration in one nucleotide base pair (A,T,C, or G). SNPs have arisen over centuries of human evolution and, therefore, are shared by human subpopulations. For example, in about every 1000 base pairs, two random individuals will exhibit a difference in their DNA sequence—one person might have a G at that location, while the other person has a T. This adds up to millions of SNP differences between humans.

Because about 99.5% of human DNA sequences are the same, these variations have diagnostic value.⁵ SNPs are of interest for medical as well as pharmacological research. Researchers can now scan the genomes of multiple individuals with the same disease to look for SNPs associated with that disease that healthy individuals do not have. If they find such an SNP, it could contribute to the disease process or act as a marker for a nearby mutation that is involved. In addition, profiling a person’s SNPs could tell researchers whether certain drugs will be more or less likely to work in that individual. This will expand the era of customized (personalized) drug therapy.