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Principles of Forensic DNA for Officers of the Court

DNA Typing - RFLP

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The process used to examine the VNTRs from a forensic sample is called restriction fragment length polymorphism (RFLP). The technique takes advantage of the fact that the DNA fragment containing the 25 copies is larger than the corresponding fragment from the other chromosome containing the 18 copies.

Analyses of the lengths of the fragments reveal that when looking at multiple VNTRs within and between individuals, no two people have the same assortment of lengths. This technique became known to the public as "DNA fingerprinting" because of its powerful ability to discriminate between unrelated individuals.

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