DNA fingerprinting, also known as DNA testing, typing, profiling, analysis, or genetic fingerprinting, identifies individuals based on their DNA profile. Developed by Dr. Alec Jeffreys in 1985, it uses variations in repeating sequences of DNA called VNTR or STR markers. DNA fingerprinting is widely used in forensic science, paternity testing, and ecological research. It can identify a person’s presence and activity at a crime scene and aid in the identification of extra pair offspring in ecological research.
A DNA fingerprint is the same thing as DNA testing, DNA typing, DNA profiling, DNA analysis, and genetic fingerprinting. It refers to the identification of an individual based on their DNA profile. One of the most prominent uses of this technique is in forensic science, and this is widely known due to its prominent use in police proceedings.
In 1985, Dr. Alec Jeffreys, and the English geneticist, were the first to describe DNA fingerprinting when he developed a technique for examining variations in the repeating sequences of DNA which allowed identity tests to be performed on human subjects. The repeated sections are called variable number of tandem repeats, or VNTR, and the technique developed by Dr. Jeffreys was called RFLP because it used restriction fragment length polymorphism. The first court cases to use Dr. Jeffreys’ methodology were English cases involving immigration and a double homicide, which he helped solve.
In DNA sample processing in forensic laboratories in the United States, smaller versions of VNTR, called STR markers, are used. The DNA is copied using polymerase chain reaction (PCR) and the sample is then genotyped. The combination of individual STR genotypes produces the DNA profile or fingerprint. It can then be compared to other samples which are known reference samples of people such as the victim and the identified suspects.
With the advent of DNA testing, the types of forensically useful biological evidence have expanded. Furthermore, DNA has shown that evidence such as waste tissues, cotton buds, toothpicks, cigarette butts, postage stamps and empty bottles, cans or glasses have more to offer than the possibility of a fingerprint. All of these objects, with their sweat, skin, mucus, blood, semen, earwax and/or saliva offer the possibility of DNA and the ability to identify a person’s presence and possibly activity at a crime scene.
DNA fingerprinting also has applications in paternity testing and ecological research. In paternity tests, the child’s genotype is compared to the mother and alleged father(s). No match will result in exclusion. If there is a match or inclusion, the DNA fingerprint is compared to the appropriate ethnic population database and the likelihood of relationship is calculated and reported. In ecological research, DNA fingerprinting has aided in the identification of extra pair offspring (EPO), the name given to chicks that were sired by a male partner other than their social partner. This led to the realization that EPO is ahead of their half-siblings due to their mothers’ actions.
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