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A DNA fingerprint is the same thing as DNA testing, DNA typing, DNA profiling, DNA analysis and genetic fingerprinting. It refers to identification of an individual based on his or her DNA profile. One of the most important uses of this technique is in forensic science, and this is widely known due to its prominent use in police procedurals.
In 1985, Dr. Alec Jeffreys, and English geneticist, became the first to describe DNA fingerprinting when he worked out a technique to examine variations in DNA repeat sequences that allowed identity tests to be performed on human subjects. The repeated sections are called variable number of tandem repeats or VNTRs and the technique that Dr. Jeffreys developed was called RFLP because it used restriction fragment length polymorphism. The first court cases in which Dr. Jeffreys' methodology was used in were English case involving immigration and a double homicide, which it helped solve.
In DNA sample processing in forensic labs in the US, smaller versions of VNTRs, called STR markers are used. The DNA is copied using polymerase chain reaction (PCR) and the sample is then genotyped. Combining individual STR genotypes yields the DNA profile or fingerprint. It can then be compared to other samples that are known reference samples from people such as the victim and identified suspects.
With the advent of DNA testing, the types of biological evidence that were forensically useful expanded. In addition, DNA made evidence such as discarded tissues, cotton swabs, toothpicks, cigarette butts, stamps, and empty bottles, cans, or glasses have more to offer than the possibility of a fingerprint. All these items, with their sweat, skin, mucus, blood, semen, ear wax, 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 application in paternity testing and ecological research. In paternity testing, the genotype of child is compared to mother and alleged father(s). No match leads to an exclusion. If there is a match, or inclusion, then the DNA fingerprint is compared to appropriate ethnic population database, and the probability of relationship is calculated and reported. In ecological research, DNA fingerprinting has helped in identification of extra pair offspring (EPO) the name given to chicks that have been sired by a male partner other than their social partner. This has led to the realization that the EPO are ahead of their half siblings because of actions by their mothers.