DNA fingerprinting, a technique for comparing the nucleotide sequences of fragments of DNA from different sources. The fragments are obtained by treating the DNA with various endonucleases, enzymes that break DNA strands at specific sites. There is a chance of 1 in 30 billion that two persons who are not monozygotic twins would have identical DNA fingerprints. To resolve the complexities of the process, short, tandemly repeated, highly specific “minisatellite” genomic sequences are used. A wild-type M13 bacteriophage that identifies the differences is confined to two clusters of 15-base-pair repeats in the protein III gene of the bacteriophage. The specificity of the probe makes it applicable to questions of forensic science.
