Abstract
The application of DNA fingerprinting has become very broad in forensic analysis, patient
identification, diagnostic medicine, and wildlife poaching, since every individual's DNA structure is
identical within all tissues oftheir body. DNA fingerprinting was initiated by the use of restriction
fragment length polymorphisms (RFLP). In 1987, Nakamura et aL2 found that a variable number
of tandem repeats (VNTR) often occurred in the alleles. The probability of different individuals
having the same number of tandem repeats in several different alleles is very low. Thus, the
identification of VNTR from genomic DNA became a very reliable method for identification of
individuals. Take the Huntington gene as an example, there are CAG trinucleotide repeats. For
normal people, the number of CAG repeats is usually between 10 and 40. Since people have
chromosomes in pairs, the possibility oftwo individuals having the same VNTR in the Huntington
gene is less than one percent, ifwe assume equal distribution for various repeats. When several allels
containing VNTR are analyzed for the number of repeats, the possibility of two individuals being
exactly identical becomes very unlikely. Thus, DNA fingerprinting is a reliable tool for forensic
analysis. In DNA fingerprinting, knowledge of the sequence of tandem repeats and restriction
endornuclease sites can provide the basis for identification.
