A molecular genetic method that enables identification of individuals using hair, blood, semon or other biological samples, based on unique patterns (polymorphisms) in their DNA. When first described in 1984 by British scientist Alec Jeffreys, the technique focused on sequences of DNA called mini-satellites, that contained repeating patterns with no known function. These sequences are unique to each individual, with the exception of identical twins.
Different DNA fingerprinting methods exist, using either Restriction Fragment Length Polymorphism (RFLP) or PCR or both, and targeting different areas of DNA including those with known variations in single nucleotides (single nucleotide polymophisms; SNPs), short tandem repeats (STRs) and other various repeating polymophic regions. The odds of identifying an individual correctly depend on the number of repeating sequences tested and their size.
DNA fingerprinting, when used for forensic science, makes use of probes that target regions of DNA that are specific to humans, thus eliminating any possibility of contamination by extraneous DNA from bacteria, plants, insects or other sources.